U.S. patent application number 11/140371 was filed with the patent office on 2005-10-13 for peg-modified uricase.
This patent application is currently assigned to Phoenix Pharmacologics, Inc.. Invention is credited to Clark, Mike A., Ensor, Charles Mark, Holtsberg, Frederick Wayne.
Application Number | 20050226859 11/140371 |
Document ID | / |
Family ID | 25445342 |
Filed Date | 2005-10-13 |
United States Patent
Application |
20050226859 |
Kind Code |
A1 |
Ensor, Charles Mark ; et
al. |
October 13, 2005 |
Peg-Modified Uricase
Abstract
The present invention is directed to uricase modified with
polyethylene glycol and to methods of treating different illnesses
characterized by increased circulating uric acid levels, including
but not limited to, hyperuricemia and tumor lysis syndrome.
Inventors: |
Ensor, Charles Mark;
(Lexington, KY) ; Clark, Mike A.; (Riverton,
WY) ; Holtsberg, Frederick Wayne; (Nicholasville,
KY) |
Correspondence
Address: |
WOODCOCK WASHBURN LLP
ONE LIBERTY PLACE, 46TH FLOOR
1650 MARKET STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
Phoenix Pharmacologics,
Inc.
San Diego
CA
|
Family ID: |
25445342 |
Appl. No.: |
11/140371 |
Filed: |
May 27, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11140371 |
May 27, 2005 |
|
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09921380 |
Aug 2, 2001 |
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6913915 |
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Current U.S.
Class: |
424/94.6 ;
435/228 |
Current CPC
Class: |
A61P 13/00 20180101;
A61P 13/12 20180101; A61P 19/06 20180101; A61P 35/00 20180101; C12N
9/0046 20130101; A61K 38/00 20130101 |
Class at
Publication: |
424/094.6 ;
435/228 |
International
Class: |
A61K 038/46; C12N
009/80 |
Claims
1-47. (canceled)
48. A compound comprising a uricase protein covalently bonded to
polyethylene glycol, wherein polyethylene glycol is covalently
attached to said uricase protein at one or more amino acid
residues, wherein said polyethylene glycol has a total weight
average molecular weight of about 12,000 to about 50,000 and
wherein said uricase protein comprises 12 to about 30 polyethylene
glycol molecules per uricase protein unit.
49. The compound of claim 48 wherein said uricase has an amino acid
sequence comprising SEQ ID NO:6.
50. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.12, Lys.sup.16, Lys.sup.28, Lys.sup.64, Lys.sup.72,
Lys.sup.117, Lys.sup.156, Lys.sup.167, and Lys.sup.262.
51. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.156.
52. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.167.
53. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.12.
54. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.64.
55. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.262.
56. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.117.
57. The compound of claim 49 wherein polyethylene glycol is
covalently attached to uricase at amino acid residues other than
Lys.sup.16, Lys.sup.28, and Lys.sup.72.
58. A compound comprising a uricase protein covalently bonded via a
linking group to polyethylene glycol, wherein the polyethylene
glycol has a total weight average molecular weight of about 12,000
to about 50,000, wherein the linking group is selected from the
group consisting of a succinimide group, an amide group, an imide
group, a carbamate group, an ester group, an epoxy group, a
carboxyl group, a hydroxyl group, a carbohydrate, a tyrosine group,
a cysteine group, a histidine group and combinations thereof and
wherein said uricase is a functional monomer comprises 12 to about
30 polyethylene glycol molecules per uricase protein.
59. The compound of claim 58, wherein said linking group is a
succinimide group.
60. The compound of claim 59, wherein said succinimide group is
succinimidyl succinate, succinimidyl propionate, succinimidyl
carboxymethylate, succinimidyl succinamide, N-hydroxy succinimide
or combinations thereof.
61. The compound of claim 60, wherein said succinimide group is
succinimidyl succinate, succinimidyl propionate or combinations
thereof.
62. The compound of claim 58, wherein said uricase is derived from
a microorganism selected from the group consisting of Asperigillus
flavus, Candida utilis, Arthrobacter protoformiae, and combinations
thereof.
63. The compound of claim 58 wherein said uricase protein unit is
covalently bonded to 12 to about 25 polyethylene glycol
molecules.
64. The compound of claim 58, wherein said uricase protein unit is
covalently bonded to about 18 to about 22 polyethylene glycol
molecules.
65. The compound of claim 58, wherein said uricase protein unit is
covalently bonded to about 20 polyethylene glycol molecules.
66. A method of reducing uric acid levels in a patient comprising
administering to said patient a therapeutically effective amount of
the compound of claim 48.
67. A method of reducing uric acid levels in a patient comprising
administering to said patient a therapeutically effective amount of
the compound of claim 58.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to uricase modified with
polyethylene glycol and to methods for treating number of different
illnesses characterized by increased circulating uric acid
levels.
BACKGROUND OF THE INVENTION
[0002] Uric acid is a product of purine metabolism in birds,
reptiles, and primates, including humans. Uric acid is produced in
the liver by oxidation of xanthine and hypoxanthine. Xanthine is an
intermediate in the catabolism of guanine nucleotides while
hypoxanthine is produced during the breakdown of adenine
nucleotides. In most mammals, uric acid is further oxidized by the
enzyme urate oxidase to allantoin. Allantoin, because of its lost
pyrimidine ring, shows a more than 20 times greater water
solubility than uric acid.
[0003] Urate oxidase, also called uricase, is an enzyme of the
purine degradation pathway. Uricase catalyzes the conversion of
uric acid+O.sub.2 into allantoin+CO.sub.2.
[0004] Humans lack uricase and do not produce allantonin. This is
the result of a mutation that introduces a premature termination
codon in the coding sequence of the human uricase gene (Wu et al.,
J. Mol. Evol. 34:78-84, 1992; Wu et al., Proc Natl Acad Sci USA
91:742-6, 1994, each of which are incorporated by reference). As a
consequence of this mutation, purine catabolism in humans
terminates with the production of uric acid which is relatively
insoluble (the solubility index in distilled water is 13.2 mg/dl)
making humans susceptible to a pathological condition known as
hyperuricemia. Renal handling of uric acid is complex and requires
glomerular filtration, reabsorption of filtered urate, tubular
secretion, and finally postsecretory reabsorption.
[0005] Hyperuricemia is defined as occurring when the serum level
of uric acid is above 8 mg/dl. Hyperuricemia can result in the
formation of uric acid crystals in the serum, which can precipitate
in joints, skin and kidneys. This can result in inflammation of the
joints (gout), renal failure, metabolic acidosis, and hyperkalemia.
Overproduction of uric acid can have a variety of origins,
including congenital metabolic defects, Lesch-Nyhan syndrome,
excess ingestion of purine or proteins, and treatments with
uricosuric drugs (Kelley, W. N. and Wortman, R. L. Textbook of
Rheumatology, 5.sup.th edition, pp 1313-1351, 1997; which is
incorporated by reference). Hyperuricemia is also found in patients
that have had heart or kidney transplants and are being treated
with immunosupressive agents. Hyperuricemia can lead to the loss of
kidney function in these patients and can produce significant
morbidity and mortality.
[0006] Hyperuricemia is also found in patients with malignant
diseases. Chemotherapy and radiation therapy of cancer patients can
induce a life-threatening condition known as tumor lysis syndrome
(Kalemkerian, G. P., Darwish, B., and Varterasian, M. L. Am J. Med.
103, 363-367, 1997; Lorigan, P. C., Woodings, P. L., Morgenstern,
G. R., and Scarffe, J. H. Ann Oncol. 7, 631-636, 1996; Hande, K.
R., and Garrow, G. C. Am. J. Med. 94, 133-139, 1993). Hematologic
malignancies, such as leukemias and lymphomas, are responsible for
most cases of tumor lysis syndrome. Tumor lysis syndrome is
characterized by the rapid development of hyperuricemia,
hyperkalemia, hyperphosphatemia, and acute renal failure. Acute
renal failure is the result of the intrarenal precipitation of uric
acid. Tumor lysis syndrome is often triggered by cell death induced
by chemotherapy or radiotherapy, resulting in the release of
intracellular substances. However, occasionally cancer patients
with a heavy tumor burden may exhibit hyperuricemia and other
features of tumor lysis syndrome even in the absence of
radiotherapy or chemotherapy because of the high turnover of
malignant cells with subsequent catabolism of released purines into
uric acid.
[0007] Therapy for the prevention and treatment of the acute renal
failure associated with tumor lysis syndrome is a considerable
challenge and is currently unsatisfactory for a number of reasons.
Methods of treating hyperuricemia include hydration, urinary
alkalinization, osmotic diuresis and allopurinol therapy. However,
the difficulty in the treatment of hyperuricemia lies in the
potential for aggravating other consequences of tumor lysis
syndrome. For example, alkalinization of urine to increase uric
acid solubility facilitates precipitation of calcium phosphate.
Allopurinol (4-hydroxypurinol), an analogue of xanthine, has long
been the standard treatment for hyperuricemia and also for the
prevention of tumor lysis syndrome. Allopurinol is converted to
oxypurinol, which then binds to and inhibits xanthine oxidase, the
enzyme that catalyzes the conversion of hypoxanthine and xanthine
to uric acid. As a result, uric acid production is inhibited, and
xanthine and hypoxanthine concentrations increase. However,
allopurinol does not remove uric acid that is already present and
deposited intrarenally as crystals. As a result, it is often
several days (sometimes 10-14 days) from the initial treatment with
allopurinol before a significant decrease in uric acid in serum can
be observed. While the solubilities of xanthine and hypoxanthine
are only slightly greater than that of uric acid, the purines are
catabolized to xanthine, hypoxanthine, and uric acid during
allopurinol treatment, rather than mostly to uric acid. The result
is that the urinary concentration of uric acid decreases below its
solubility and further formation of uric acid crytstals is
prevented. However, during excessive catabolism of purines,
allopurinol therapy may lead to intrarenal precipitation of
hypoxanthine and xanthine, with further aggravation of acute renal
failure. This situation has been well documented in clinical
practice. Furthermore, allopurinol therapy is also associated with
significant toxicity and can cause death. Allopurinol can produce
severe toxic effects, including cutaneous hypersensitivity
reactions, leukopenia, and hepatomegaly. This drug has been also
implicated in the induction of tubulointerstitial nephritis. In
addition, allopurinol may cause adverse drug interactions, as has
been shown for 6-mercaptopurine and adenine arabinoside, drugs
often used to treat lymphoproliferative disease and leukemia
(Lauter, C B, Bailey, E J, Lerner, A M. J. Infect. Dis 1976; 134,
75-79). Finally, although allopurinol can block the formation of
uric acid, it does little to solubilize the uric acid which is
already present. All of these adverse effects sometimes make
allopurinol ineffective for the treatment of acute hyperuricemia in
tumor patients. Thus allopurinol is not an ideal drug for the
treatment of hyperuricemia.
[0008] Dialysis and continuous ateriovenous hemodialysis are
additional methods that are used to remove uric acid in patients
with hyperuricemia. However, these treatment methods are
problematic in patients with malignancies because of the risk for
severe bleeding caused by thrombocytopenia or the need for
anticoagulation. Furthermore, because of the invasive nature of
these treatments, there is an increased risk for fatal infections
in patients who are in many instances immunocompromised due to
their illness or therapy they have received.
[0009] Uricase has been shown to be an effective treatment for
hyperuricemia and tumor lysis syndrome (London, M., and Hudson, P.
B. Science, 125, 937-938, 1957; Oberling, F. and Lang, J. M.
Nouvelle Presse Med 3, 2026, 1974; Robert, A., Corberand, J. and
Regnier, C. Rev. Med. Toulouse 12, 1093-1100, 1976; Masera, G., et.
al., J. Pediatrics 100, 152-155, 1982; Jankovic, M., et. al. Am. J.
Pediatr. Hematol. Onocol. 7, 202-204, 1985; Masera, G. and
Jankovic, M. Ann. Oncol. 8, 407, 1996; Jones, D. P, Mahmoud, H. and
Chesney, R. W. Pediatr. Nephrol. 9, 206-212, 1995). Treatment with
uricase converts uric acid into the highly soluble allantoin.
Furthermore, uricase, if adequately filtered into the urine, may
even dissolve already precipitated uric acid crystals and improve
renal function.
[0010] Uricase has a number of advantages in the treatment of
hyperuricemia and nephrolithiasis including the speed of the
hypouricemic effect (reduction of hyperuricemia of the order of 50%
in less than 24 h) and better protection of the kidney against
lithiasis compared with other drugs such as allopurinol.
[0011] Uricase is only available in a few countries, currently
limiting the use of this therapy. Uricase extracted from
Aspergillus flavus through a complex manufacturing process, has
been commercially available from Sanofi (Clin-Midy, Paris, France)
under the trade name Uricozyme in France since 1975 and in Italy
since the early 1980s. This drug has been extensively studied in
Europe and has been shown to be very effective in rapidly lowering
levels of uric acid in patients within minutes of administration
(Oberling, F. and Lang, J. M. Nouvelle Presse Med 3, 2026, 1974;
Robert, A., Corberand, J. and Regnier, C. Rev. Med. Toulouse 12,
1093-1100, 1976). This treatment is used very often in patients to
prevent tumor lysis syndrome. In one study involving over 400
patients, uricase treatment effectively eliminated tumor lysis
syndrome (Masera, G. and Jankovic, M. Ann. Oncol. 8, 407, 1996). In
the United States, Uricozyme has been extensively tested by a group
of investigators at St. Jude Childrens Hospital and the University
of Tennessee (Pui, C.-H., et al. Leukemia, 11, 1813-1816, 1997).
These investigators treated 126 children in a 3 year period and
found uricase treatment to be much more rapid and effective in
reducing serum uric acid levels than allopurinol. Furthermore, none
of the uricase treated individuals developed tumor lysis syndrome
or required dialysis.
[0012] Although oncologists are well aware of the potential
advantages of uricase, this therapy has not been widely recognized
in the renal community. An obstacle for a more general application
of uricase in hyperuricemia may be the complicated manufacturing
process of the enzyme involving fermentation, extraction, and
purification, which clearly limits its commercial availability, as
well as the standardization of enzyme activity. The uricase
currently used as a drug is obtained by culturing Aspergillus
flavus and isolating the enzyme from the culture medium by
extraction, followed by several purification steps. While it is
possible to obtain highly purified uricase, this method has
disadvantages. Aspergillus flavus is not easy to work with because
of its physiology and genetics (WOLOSHUK et. al. Applied Environ.
Microbiol., 55, 86-90, 1989), making it difficult to obtain strains
that can produce substantial amounts of the enzyme. Aspergillus
flavus can also produce aflatoxins, which can be difficult to
remove during the purification process. The purified uricase must
be checked to ensure that it is free from these toxins. In
addition, because of the foreign nature of the Aspergillus enzyme,
therapy is many times limited to a single dose due to the risk of
hypersensitivity reactions.
[0013] Although uricase has been tested in the United States, it is
not an approved therapy because of the of a high incidence of
allergic reactions to this foreign protein. The clinical use of
uricase is also compromised by its short circulating half-life.
(See, Park et al., Anticancer Res., 1:373-6 (1981).
[0014] Hypersensitivity to uricase and the short circulating
half-life of uricase can be overcome by the covalent attachment of
polyethylene glycol (PEG) (Chen, R. H.-L., et. al. Biochim.
Biophys. Acta 660,293-298, 1981; Nishimara, H., Matsushima, A. and
Inada, Y. Enzyme, 26, 49-53, 1981; Savoca, K. V., Davis, F. F. and
Palczuk, N. C. Int. Archs. Allegy Appl. Immun. 75, 58-67, 1984;
Tsuji, J.-I., et. al. Int. J. Immunopharmac. 7, 725-730, 1985). The
attachment of PEG to proteins has been shown to greatly reduce the
antigenicity of foreign proteins. For example, formulating a
heterologous protein with polyethylene glycol (PEG) to reduce the
antigenicity has been proven with the approval of Oncaspar (E. coli
Asparaginase). Previous investigators have attached PEG (Molecular
Weight 5000) to uricase and successfully treated a small number of
patients (Davis, S., Park, Y. K., Abuchowski, A. and Davis, F. F.
Lancet 2, 281-283, 1981; Chua, C. C., et. al. Ann. Intern. Med.
109, 114-117, 1988). Davis et. al. (1981) treated patients with a
single dose of PEG-uricase (uricase isolated from Candida utilis)
(120 IU/m.sup.2 surface area, intravenously). Serum uric acid fell
to undetectable levels within 60 minutes after injection, and
remained undetectable for at least 32 hours. The serum half-life of
PEG-5,000 uricase was 6 hours. The half-life of native
(unpegylated) uricase was noted to be less than 4 hours in other
studies. Precipitating antibodies to PEG-uricase or native uricase
were not detected in any patient. Davis et al. noted that PEG-5,000
uricase offered a potentially major therapeutic advantage over
native uricase in the treatment of hyperuricemic diseases. Chua, et
al. (1988) treated a patient with Non-Hodgkin lymphoma with uricase
purified from Arthrobacter protoformiae modifed with PEG-5,000. The
patient was treated by intramuscular injection on four separate
days. Serum uric acid level fell sharply after each dose. No
antibodies to either PEG-5,000 uricase or native uricase were
detected through the 26.sup.th day post dosing. Chua et al.
concluded that PEG-5000 uricase may be useful for treating
hyperuricemia in the setting of advanced hematologic
malignancies.
[0015] There is a need for the more efficient production and
formulation of uricase whereby the disadvantages associated with
the use of uricase in the treatment of patients with high uric acid
levels as discussed above can be overcome. The present invention is
directed to these, as well as other, important ends.
SUMMARY OF THE INVENTION
[0016] The present invention addresses the needs identified above
in that it provides formulations of uricase which overcome the
disadvantages of uricase compositions used to date.
[0017] The present invention is directed to uricase modified with
polyethylene glycol. In a preferred embodiment, uricase is modified
with polyethylene glycol having a total weight average molecular
weight of about 10,000 to about 50,000, directly or through a
biocompatible linking group. In a more preferred embodiment,
uricase is modified with polyethylene glycol having a total weight
average molecular weight of about 10,000 to about 30,000. In an
even more preferred embodiment, uricase is modified with
polyethylene glycol having a total weight average molecular weight
of about 20,000.
[0018] Another embodiment of the invention is directed to methods
of treating uric acid related diseases including hyperuricemia,
tumor lysis syndrome, and nephrolithiasis, among others, comprising
administering a therapeutically effective amount of a compound
comprising PEG-modified uricase. In a preferred embodiment uricase
is modified with polyethylene glycol having a total weight average
molecular weight of about 20,000.
[0019] In some embodiments the present invention provides methods
of enhancing the circulating half life of uricase comprising
modifying said uricase by covalently bonding said uricase via a
linking group to polyethylene glycol, wherein the polyethylene
glycol has a total weight average molecular weight of about 10,000
to about 30,000, and wherein the linking group is selected from the
group consisting of a succinimide group, an amide group, an imide
group, a carbamate group, an ester group, an epoxy group, a
carboxyl group, a hydroxyl group, a carbohydrate, a tyrosine group,
a cysteine group, a histidine group and combinations thereof.
[0020] In some embodiments the present invention provides methods
of enhancing the anti-uric acid activity of uricase comprising
modifying said uricase by covalently bonding said uricase via a
linking group to polyethylene glycol, wherein the polyethylene
glycol has a total weight average molecular weight of from about
10,000 to about 30,000, and wherein the linking group is selected
from the group consisting of a succinimide group, an amide group,
an imide group, a carbamate group, an ester group, an epoxy group,
a carboxyl group, a hydroxyl group, a carbohydrate, a tyrosine
group, a cysteine group, a histidine group and combinations
thereof.
[0021] In some embodiments, the present invention provides methods
of reducing uric acid levels in a patient comprising administering
to said patient a therapeutically effective amount of a compound
comprising uricase covalently bonded via a linking group to
polyethylene glycol, wherein the polyethylene glycol has a total
weight average molecular weight of from about 10,000 to about
30,000. In a preferred embodiment uricase is modified with
polyethylene glycol having a total weight average molecular weight
of about 20,000.
[0022] In some embodiments the present invention provides methods
of treating uric acid related disorders in a patient comprising
administering to said patient a therapeutically effective amount of
a compound comprising uricase covalently bonded via a linking group
to polyethylene glycol, wherein the polyethylene glycol has a total
weight average molecular weight of from about 10,000 to about
30,000. In a preferred embodiment uricase is modified with
polyethylene glycol having a total weight average molecular weight
of about 20,000.
[0023] In some embodiments, the present invention provides a
compound comprising uricase coupled to polyethylene glycol, without
a linking group wherein the polyethylene glycol has a total weight
average molecular weight of about 10,000 to about 30,000. In a
preferred embodiment uricase is modified with polyethylene glycol
having a total weight average molecular weight of about 20,000.
[0024] These and other aspects of the present invention will be
elucidated in the following detailed description of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0025] Overview
[0026] Uricase may be found in many microorganisms and is useful
for the treatment of many diseases and disorders in humans.
However, uricase is antigenic and rapidly cleared from circulation
in a patient. These problems may be overcome by covalently
modifying uricase with polyethylene glycol (PEG).
[0027] The present invention is based on the discovery that uricase
modified with polyethylene glycol provides excellent results in
treating certain types of diseases and disorders related to
elevated levels of uric acid in humans. When compared to native
uricase, uricase-PEG retains most of its enzymatic activity, is far
less antigenic, has a greatly extended circulating half-life, and
is much more efficacious in the treatment of diseases and disorders
including hyperuricemia and tumor lysis syndrome, among others.
PEG-20,000 is especially preferred as it possesses preferred
enzymatic activity levels, antigenicity, circulating half-life,
efficacy, and relative ease of manufacture.
[0028] Definitions
[0029] Throughout the present disclosure, the following
abbreviations may be used: PEG, polyethylene glycol; SS,
succinimidyl succinate; SSA, succinimidyl succinamide; SPA,
succinimidyl propionate; and NHS, N-hydroxy-succinimide.
[0030] Uricase covalently modified with polyethylene glycol (with
or without a linking group) may be hereinafter referred to as
"uricase-PEG", "urate oxidase-PEG", or "PEG-uricase".
[0031] "Polyethylene glycol" or "PEG" refers to mixtures of
condensation polymers of ethylene oxide and water, in a branched or
straight chain, represented by the general formula
H(OCH.sub.2CH.sub.2).sub.nOH, wherein n is at least 4.
"Polyethylene glycol" or "PEG" is used in combination with a
numeric suffix to indicate the approximate weight average molecular
weight thereof. For example, PEG-5,000 refers to polyethylene
glycol having a total weight average molecular weight of about
5,000; PEG-12,000 refers to polyethylene glycol having a total
weight average molecular weight of about 12,000; and PEG-20,000
refers to polyethylene glycol having a total weight average
molecular weight of about 20,000.
[0032] As used herein, the term "patient" refers to an animal,
preferably a mammal, and more preferably a human.
[0033] As used herein, the term "uric acid related disease" refers
to diseases and disorders characterized by elevated levels of uric
acid. Uric acid related disorders include without limitation,
hyperuricemia, tumor lysis syndrome, and nephrolithiasis, among
others.
[0034] As used herein, the term "about" refers to +/-10% of the
value.
[0035] As used herein, the term "biocompatible" refers to materials
or compounds which are generally not injurious to biological
functions and which will not result in any degree of unacceptable
toxicity, including allergenic and disease states.
[0036] "Circulating half life" refers to the period of time, after
injection of the modified uricase into a patient, until a quantity
of the uricase has been cleared to levels one half of the original
peak serum level. Circulating half life may be determined in any
relevant species, including humans or mice.
[0037] As used herein, the terms "covalently bonded" and "coupled"
are used interchangeably and refer a covalent bond linking uricase
to the PEG molecule, either directly or through a linker.
[0038] Uricase
[0039] In the present invention, the uricase gene may be derived,
cloned or produced from any source, including, for example, from
microorganisms, or via recombinant biotechnology, or any
combination thereof. For example, uricase may be cloned from
microorganisms including but not limited to Asperigillus flavus,
Candida utilis, and Arthrobacter protoformiae. In some embodiments,
the uricase used in the present invention may have the amino acid
sequence set forth in the appended Sequence Listing.
[0040] Uricase may also may cloned from a large number of other
organisms, including but not limited to bacteria, of the genera
Streptomyces and Bacillus; fungi, (including the yeast) of the
genera Saccharomyces, Schizosaccaromyces, Emericella, Aspergillus,
and Neurospora; the fruit fly (Drosophila); mammals, including pig
(Sus scrofa), squirrel monkey (Samiri sciureus), baboon (Papio),
and rhesus macaque (Macaca mulatta); and plants including the
chickpea (Cicer arietinum), common bean (Phaseolus vulgaris),
potato (Solanum tuberosum) and pea (Pisum sativum).
[0041] Polyethylene Glycol
[0042] There are many polyethylene glycols available that differ in
their molecular weight and linking group. These PEGs can have
varying effects on the antigencity, immunogenicity and circulating
half-life of a protein (Zalipsky, S. and Lee, C. Polyethylene
Glycol Chemistry: Biotechnical and Biomedical Applications. Pp.
347-370, Plenum Press, New York, 1992; Monfardini, C., et. al.
bioconjugate Chem. 6, 62-69, 1995; Delgado C; Francis GE; Fisher D.
The uses and properties of PEG-linked proteins. Crit. Rev. Ther.
Drug Carrier Sys., 9:249-304, 1992.)
[0043] In one embodiment of the present invention, the polyethylene
glycol has a total weight average molecular weight of about 10,000
to about 50,000; more preferably from about 12,000 to about 40,000,
more preferably from about 15,000 to about 30,000; and most
preferably about 20,000. Generally, polyethylene glycol with a
molecular weight of 30,000 or more is difficult to dissolve, and
yields of the formulated product are greatly reduced.
[0044] The polyethylene glycol may be a branched or straight chain,
preferably a straight chain. Increasing the molecular weight of the
polyethylene glycol generally tends to decrease the immunogenicity
of the uricase. The polyethylene glycols having the molecular
weights described in the present invention may be used in
conjunction with uricase, and, optionally, a biocompatible linking
group, to treat diseases and disorders relating to elevated levels
of uric acid.
[0045] Pegylation
[0046] Uricase may be covalently bonded to PEG via a biocompatible
linking group, using methods known in the art, as described, for
example, by Park et al, Anticancer Res., 1:373-376 (1981); and
Zaplipsky and Lee, Polyethylene Glycol Chemistry: Biotechnical and
Biomedical Applications, J. M. Harris, ed., Plenum Press, NY,
Chapter 21 (1992), the disclosures of which are hereby incorporated
by reference herein in their entirety.
[0047] The linking group used to covalently attach PEG to uricase
may be any biocompatible linking group. As discussed above,
"biocompatible" indicates that the compound or group is non-toxic
and may be utilized in vitro or in vivo without causing injury,
sickness, disease or death. PEG can be bonded to the linking group,
for example, via an ether bond, an ester bond, a thiol bond or an
amide bond. Suitable biocompatible linking groups include, for
example, an ester group, an amide group, an imide group, a
carbamate group, a carboxyl group, a hydroxyl group, a
carbohydrate, a succinimide group (including, for example,
succinimidyl succinate (SS), succinimidyl propionate (SPA),
succinimidyl carboxymethylate (S CM), succinimidyl succinamide (S
SA) or N-hydroxy succinimide (NHS)), an epoxide group, an
oxycarbonylimidazole group (including, for example,
carbonyldimidazole (CDI)), a nitro phenyl group (including, for
example, nitrophenyl carbonate (NPC) or trichlorophenyl carbonate
(TPC)), a trysylate group, an aldehyde group, an isocyanate group,
a vinylsulfone group, a tyrosine group, a cysteine group, a
histidine group or a primary amine. Preferably, the biocompatible
linking group is an ester group and/or a succinimide group. More
preferably, the linking group is SS, SPA, SCM, SSA or NHS; with SS,
SPA or NHS being more preferred, and with SS or SPA being most
preferred.
[0048] In the present invention, a common feature of the most
preferred biocompatible linking groups is that they attach to a
primary amine of uricase via a maleimide group. Once coupled with
uricase, SS-PEG has an ester linkage next to the PEG, which may
render this site sensitive to serum esterase, which may release PEG
from uricase in the body. SPA-PEG and PEG2-NHS do not have an ester
linkage, so they are not sensitive to serum esterase.
[0049] In the present invention, the particular linking groups do
not appear to influence the circulating half-life of PEG-uricase or
its specific enzyme activity. However, if a linking group is used,
it is important to use a biocompatible linking group. The PEG which
is attached to the protein may be either a single chain, as with
SS-PEG, SPA-PEG and SC-PEG, or a branched chain of PEG may be used,
as with PEG2-NHS.
[0050] Alternatively, uricase may be coupled directly to PEG (i.e.,
without a linking group) through an amino group, a sulthydral
group, a hydroxyl group or a carboxyl group. In a preferred
embodiment, PEG is coupled to lysine residues on uricase.
[0051] Uricase-PEG
[0052] The attachment of PEG to uricase increases the circulating
half-life of uricase.
[0053] The number of PEG units on uricase appears to be related to
the circulating half life of the enzyme, while the amount of
retained enzymatic activity appears related to the average
molecular weight of the PEG used.
[0054] It is known that increasing the number of PEG units on
uricase decreases the enzymatic activity of the enzyme. Also, it is
known that some PEG formulations are difficult to yield and yield
relatively low amounts of product. Thus, to achieve an efficacious
product, a balance needs to be achieved among circulating
half-life, antigenicity, efficiency of production, and enzymatic
activity.
[0055] Generally, PEG is attached to a primary amine of uricase.
Selection of the attachment site of polyethylene glycol on the
uricase is determined by the role of each of the sites within the
active domain of the protein, as would be known to the skilled
artisan. PEG may be attached to the primary amines of uricase
without substantial loss of enzymatic activity. As discussed above
however, the amount of retained enzymatic activity appears to be
related to the average molecular weight of the PEG used. For
example, uricase cloned from C. utilis has about 32 lysines that
may be pegylated by this procedure. In other words, the 32 lysines
are all possible points at which uricase can be attached to PEG via
a biocompatible linking group, such as SS, SPA, SCM, SSA and/or
NHS. PEG may also be attached to other sites on uricase, either via
a linking group or by direct attachment to a group on one or more
residues, as would be apparent to one skilled in the art in view of
the present disclosure.
[0056] From 1 to about 32 PEG molecules may be covalently bonded to
uricase at lysine residues. Preferably, uricase is modified with
about 5 to about 30 PEG molecules, more preferably from about 10 to
about 25 PEG molecules, more preferably from about 18 to about 22
PEG molecules and most preferably about 20 PEG molecules. In other
words, about 15% to about 95% of the primary amino groups in
uricase are modified with PEG, more preferably about 55% to about
70% of the primary amino groups in uricase are modified with PEG
and most preferably about 60% of the primary amino groups in
uricase are modified with PEG. When PEG is covalently bonded to the
end terminus of uricase, preferably only 1 PEG molecule is
utilized. In a preferred embodiment, uricase is modified with
PEG-20,000.
[0057] Uricase may be pegylated at many different sites. In a
preferred embodiment, uricase is pegylated at sites other than one
or more of the following (numbers refer to the amino acid residue
of C. utilis uricase): Lys.sup.12, Lys.sup.16, Lys.sup.28,
Lys.sup.64, Lys.sup.72, Lys.sup.117, Lys.sup.156, Lys.sup.167, and
Lys.sup.262. In some preferred embodiments, uricase is pegylated
with about twenty PEG-20,000 molecules. In one such preferred
embodiment, uricase is not pegylated at Lys.sup.56. In another
preferred embodiment, uricase is not pegylated at Lys.sup.167. In
another preferred embodiment, uricase is not pegylated at
Lys.sup.12. In another preferred embodiment, uricase is not
pegylated at Lys.sup.64. In another preferred embodiment, uricase
is not pegylated at Lys.sup.262. In another preferred embodiment,
uricase is not pegylated at Lys.sup.64. In another preferred
embodiment, uricase is not pegylated at Lys.sup.262. In another
preferred embodiment, uricase is not pegylated at Lys.sup.117. In
another preferred embodiment, uricase is not pegylated at
Lys.sup.16. In another preferred embodiment, uricase is not
pegylated at Lys.sup.28. In another preferred embodiment, uricase
is not pegylated at Lys.sup.72. In a more preferred embodiment,
uricase is not pegylated at Lys.sup.156 and Lys.sup.167. In a more
preferred embodiment, uricase is not pegyolated at Lys.sup.156,
Lys.sup.167, Lys.sup.12, Lys.sup.64, and Lys.sup.262. In an even
more preferred embodiment, uricase is not pegylated at Lys.sup.156,
Lys.sup.167, Lys.sup.12, Lys.sup.64, Lys.sup.262, and Lys.sup.117.
In a most preferred embodiment, uricase is not pegylated at
Lys.sup.156, Lys.sup.167, Lys.sup.12, Lys.sup.64, Lys.sup.262,
Lys.sup.117, Lys.sup.16, Lys.sup.28, and Lys.sup.72.
[0058] As discussed, it is known that enzymatic activity is
decreased by increasing the number of PEG units on an enzyme.
However, the present inventors have discovered that the enzymatic
activity of uricase bound to about twenty PEG-20,000 molecules is
actually higher that the enzymatic activity of the
uricase-PEG-5,000 when each is bound to the same number of PEG
molecules. Such increased activity of uricase-PEG-20,000 allows for
treatment using lower doses than previously considered possible.
Lower doses of uricase-PEG-20,000 provide the advantages of
minimizing immune responses to the uricase-PEG including reducing
potential hypersensitivity problems, minimizing anaphalxsis, and
lessening the occurrence of rashes resulting in patients
administered uricase-PEG. In mouse studies PEG-20,000 has also been
shown to be safer than other PEG formulations, in particular
PEG-5,000.
[0059] Methods of Treatment
[0060] In some embodiments, the present invention provides methods
of reducing uric acid levels in a patient comprising administering
to said patient a therapeutically effective amount of a compound
comprising uricase covalently bonded via a linking group to
polyethylene glycol, wherein the polyethylene glycol has a total
weight average molecular weight of from about 10,000 to about
30,000. In a preferred embodiment uricase is modified with
polyethylene glycol having a total weight average molecular weight
of about 20,000.
[0061] In some embodiments the present invention provides methods
of treating uric acid related disorders in a patient comprising
administering to said patient a therapeutically effective amount of
a compound comprising uricase covalently bonded via a linking group
to polyethylene glycol, wherein the polyethylene glycol has a total
weight average molecular weight of from about 10,000 to about
30,000. In a preferred embodiment uricase is modified with
polyethylene glycol having a total weight average molecular weight
of about 20,000.
[0062] A therapeutically effective amount of one of the compounds
of the present invention is an amount that is effective to reduce
uric acid levels. Generally, treatment is initiated with small
dosages which can be increased by small increments until the
optimum effect under the circumstances is achieved. Generally, a
therapeutic dosage of compounds of the present invention may be
from about 1 to about 200 mg/kg twice a week to about once every
two weeks. For example, the dosage may be about 1 mg/kg once a week
as a 2 ml intravenous injection to about 20 mg/kg once every 3
days. Uricase-PEG20,000 maybe administered several times each day,
once a day, once a week, or once every two weeks.
[0063] PEG-uricase may be mixed with a phosphate buffered saline
solution, or any other appropriate solution known to those skilled
in the art, prior to injection. The PEG-uricase formulation may be
administered as a solid (lyophilate) or as a liquid formulation, as
desired.
[0064] The methods of the present invention can involve either in
vitro or in vivo applications. In the case of in vitro
applications, including cell culture applications, the compounds
described herein can be added to cells in cultures and then
incubated. The compounds of the present invention may also be used
to facilitate the production of monoclonal and/or polyclonal
antibodies, using antibody production techniques well known in the
art. The monoclonal and/or polyclonal antibodies can then be used
in a wide variety of diagnostic applications, as would be apparent
to one skilled in the art.
[0065] The in vivo means of administration of the compounds of the
present invention will vary depending upon the intended
application. As one skilled in the art will recognize,
administration of the PEG-uricase composition of the present
invention can be carried out, for example, orally, intranasally,
intraperitoneally, parenterally, intravenously, intralymphatically,
intratumorly, intramuscularly, interstitially, intra-arterially,
subcutaneously, intraocularly, intrasynovial, transepithelial, and
transdermally.
EXAMPLES
[0066] The invention is further demonstrated in the following
examples, which are for purposes of illustration, and are not
intended to limit the scope of the present invention.
Example 1
Isolation of the Candida utilis Uricase Coding Sequence and
Construction of the Expression Plasmid
[0067] Genomic DNA was isolated from C. utilis (ATCC 9950) and used
as the template in PCR for the isolation of the uricase gene. C.
utilis was grown 100 mL YPD medium in an incubator shaker at
30.degree. C..times.250 rpm. The next day, cells from 50 mL of the
culture were pelleted by centrifugation at 1500.times.g for 10
minutes at room temperature. The pellet was resuspended in 15 ml of
SCED buffer, pH 7.5 (1 M sorbitol, 10 mM sodium citrate, pH7.5, 10
mM EDTA, 10 mM DTT). Three mg of Lyticase.TM. (Sigma, St. Louis,
Mo., Cat. No. L-4025) was added to the cells and the cells
incubated at 37.degree. C. for 60 minutes. Fifteen ml of 1% SDS was
added, mixed gently and set on ice for 5 minutes. Six ml of 5M
potassium acetate, pH 8.9, was added and mixed gently. The solution
was centrifuged at 10,000.times.g for 10 minutes at 4.degree. C.
The supernatant was transferred to a clean centrifuge tube, 2
volumes of ethanol added and incubated at room temperature for 15
minutes. The DNA was pelleted by centrifugation at 10,000.times.g
for 20 minutes at 4.degree. C. The pellet was resuspended in 10 ml
of TE buffer, pH 7.4 (10 mM Tris-HCl, pH 7.4, 1 mM EDTA). The
solution was gently extracted with an equal volume of
phenol:chloroform (1:1 v/v) followed by an equal volume of
chloroform:isoamyl alcohol (24:1). One half volume of 7.5 M
ammonium acetate, pH 7.5, and 2 volumes of ethanol was added and
the tube placed at -70.degree. C. for 10 minutes. The DNA was
pelleted centrifuge at 10,000.times.g for 10 minutes at 4.degree.
C. The pellet was air dried the and resuspended in 1 ml of TE
buffer, pH 7.5 containing 50 .mu.g RNase A. The DNA was incubated
at room temperature for 1 hour and then reprecipitated with an
equal volume of ethanol. The DNA was pelleted by centrifugation at
10,000.times.g for 10 minutes at 4.degree. C. The pellet was
resuspended in 1 ml TE buffer, pH 7.5. The concentration of the DNA
was determined by measuring the optical density at 260 nm.
[0068] PCR was used to isolated the uricase gene from the C. utilis
genomic DNA. The primers for the PCR have the following
sequences:
[0069] Forward primer, URIUfor Sna: 5'-GTG TAC GTA ATG TCA ACA ACG
CTC TCA TCA-3' (SEQ. ID. NO. 1)
[0070] Reverse primer, URIUrevH: 5'-AGA AAG CTT TTA CCA CTT GGT CTT
CTC CTT A-3' (SEQ. ID. NO. 2)
[0071] These primers place a SnaB I site at the 5' end of the
coding sequence and a Hind III site at the 3' end for subcloning
into pQE70 (Qiagen, Valencia, Calif.) for expression. The PCR
mixture contained IX Vent polymerase buffer, 2.5 mM magnesium
sulfate, 0.2 mM each dNTPs, 30 pmole of each primer, 1.8 .mu.g of
C. utilis genomic DNA and 2.5 U Vent polymerase (New England
Biolabs, Beverly, Mass.) in a 50 .mu.l final reaction volume. PCR
was carried out at 98.degree. C. for 2 minutes, followed by 30
cycles of 98.degree. C. for 30 seconds, 55.degree. C. for 30
seconds and 72.degree. C. for 60 seconds. One unit of Taq
polymerase (Gibco, Rockville, Md.) was then added and the reaction
incubated at 72.degree. C. for 7 minutes. Twenty ml of the PCR was
run on an 0.8% agarose gel. The PCR product was excised from the
gel and extracted using the Qiagen gel extraction kit. The PCR
product was subcloned into pCR2.1 (Invitrogen, Carlsbad, Calif.).
The uricase PCR product was excised from pCR2.1 using SnaB I and
Hind III and purified by agarose gel electrophoresis. pQE70 was
digested with Sph I at 37.degree. C. for 1 hour, treated with
Klenow fragment at room temperature for 15 minutes to create blunt
ends, and then incubated at 80.degree. C. for 15 minutes to
inactivate the Klenow enzyme. The treated plasmid was then digested
with Hind III at 37.degree. C. for 1 hour, run on an agarose gel
and then purified from the gel. The uricase fragment was then
ligated into the digested pQE70 to create pQE-URIC. E. coli DG101
(ATCC 47041) was transformed with the ligation reaction and
transformants were selected in the presence of ampicillin.
Transformants were screened for uricase production by growing cells
in 3 mL LB containing ampicillin (100 mg/mL) until the OD600
reached 0.5 to 0.6. Isopropyl-b-D-galactopyranoside (IPTG) was
added to 1 mM final concentration and the cultures incubated for an
additional 2 hours. Cell extracts were then analysed by
SDS-polyacrylamide gel electrophoresis and gels examined for the
presence of a 34,000 Da protein. One transformant found to produce
a 34,000 Da protein was tested and found to have uricase activity.
pQE-URIC was isolated from this transformant and the gene for
tetracycline resistance was inserted into the plasmid. For
insertion of the gene conferring tetracycline resistance into
pQE-URIC, pBR322 was digested with Eco RI and Ava I, and then
treated with Klenow polymerase and dNTPs to create blunt ends on
the digested DNA fragments. pQE-URIC was digested with XbaI and
then treated with Klenow polymerase and dNTPs. The .about.1400 bp
fragment from pBR322 containing the tetracycline resistance gene
was gel purified and ligated into pQE-URIC to create pPHX12. The
sequence of pPHX12 (SEQ ID NO:3), the uricase coding sequence (SEQ
ID NO:4) found in pPHX12 and its translated amino acid sequence
(SEQ ID 5) and the amino acid sequence of uricase as deduced from
the coding sequence found in pPHX12 (SEQ ID NO:6) are set forth in
the attached Sequence Listing which is incorporated by reference.
E. coli DG101 was transformed with pPHX12 to produce E. coli strain
PHX12 which was used for the production and purification of
uricase.
Example 2
Expression of Uricase in E. coli
[0072] For the production of uricase, PHX12 was grown in 20 L
fermentations. E. coli non-defined medium #1 was used for the
growth of PHX12 in a Bioflo IV Benchtop Fermentor (New Brunswick
Scientific, Edison, N.J.). Components of E. coli non-defined medium
#1 consist of Basal Medium, 50% glycerol, 100X salts solution, 100X
calcium chloride solution, and 1000X vitamin solution. These
components are prepared as described below.
1 Basal Medium Per Liter of Medium casamino acids 30 g ammonium
sulfate 3 g potassium phosphate, dibasic 2.5 g
[0073] Dissolve in 920 mL of water and autoclave or filter
sterilized through a 0.22 .mu.m filter.
2 Concentrated salts solution (100 X) boric acid 0.57 g copper (II)
sulfate pentahydrate 0.39 g ferric chloride, 100 g in 40 mL water
2.0 ml manganese chloride tetrahydrate 4.0 g sodium chloride 5.0 g
sodium molybdate dihydrate 0.5 g magnesium sulfate heptahydrate
25.0 g sulfuric acid 2.87 ml zinc sulfate heptahydrate 1.0 g
[0074] Dissolve in 1 liter of H.sub.2O and autoclaved or filter
sterilized through a 0.22 .mu.m filter.
[0075] 50% (v/v) Glycerol
[0076] Mix 1000 ml of glycerol and 1000 ml of H.sub.2O and
autoclave or filter through a 0.22 .mu.m filter.
3 Vitamin solution (1000 X) thiamine hydrochloride 0.26 g
[0077] Dissolve in 100 ml of H.sub.2O and filter sterilized through
a 0.22 .mu.m filter.
4 Calcium solution (100 X) Calcium chloride dihydrate 10 g
[0078] Dissolve in 1 liter of H.sub.2O and autoclave or filter
sterilized through a 0.22 .mu.m filter.
[0079] For each liter of E. coli non-defined medium #1, the
following were aseptically added to sterilized Basal Medium in the
following amounts:
[0080] 60 ml of glycerol solution
[0081] 10 ml of concentrated salts solution
[0082] 10 ml of calcium solution
[0083] 1 ml of vitamin solution
[0084] Preparation of PHX12 Inoculum
[0085] A vial of PHX12 from a Working Cell Bank stored at
-70.degree. C. was thawed and the contents aseptically transferred
to 250 mL of E. coli Non-defined Medium #1 containing 12 .mu.g/mL
tetracycline in a 500 mL baffled shake flask. The tetracycline
selection is maintained only at the shake flask level. The
inoculated baffled shake flask was incubated in an environmental
incubator at 37.degree. C. at 250 rpm. The shake flask culture was
grown for 13 to 16 hours before being aseptically transferred to
the BioFlo IV Fermentor containing 20 liters of sterile medium.
[0086] Cell Growth and Harvesting
[0087] E. coli Non-defined Medium #1 was used for the growth of
PHX12 in the fermentor. E. coli Non-defined Basal Medium was
prepared by dissolving 600 g casamino acids, 60 g ammonium sulfate,
and 50 g potassium phosphate, dibasic, in 2 L of nanopure water.
The fermentor was filled with 18.4 L of Basal Medium, 50 mL of
Antifoam B was added to the Basal Medium and then sterilized using
the sterilization cycle of the fermentor set at 121.degree. C. for
30 minutes. After sterilization, the medium was allowed to cool to
37.degree. C. or below and 200 mL of 100X calcium chloride
solution, 200 mL of 100X concentrated salts solution, 20 mL of
1000X vitamin solution, and 1200 mL of 50% glycerol solution was
aseptically added to the fermentor.
[0088] Parameters of the fermentation were as follows: Agitation
was set to 700 rpm, the temperature was set to 37.degree. C., and
the air flow was set at 20 Lpm. The inoculum was then used to seed
the fermentor. The culture was grown in the fermentor to an optical
density (A600 nm) of approximately 8. IPTG was then aseptically
added to the fermentor to a final concentration of 1 mM. The
fermentation was allowed to continue for 2 hours after the addition
of IPTG. The cells were then harvested and then immediately
concentrated to 2 to 3 L by diafiltration using a hollow fiber
filter. The cells were pelleted by centrifugation at 8,000.times.g
for 10 minutes and the cell paste was transferred to plastic
storage containers and stored at -70.degree. C. until further
processed. A typical 20 liter fermentation produced 0.5 to 0.6 Kg
of cell paste.
Example 3
Purification of Uricase
[0089] Cell paste from a 20 L fermentation was resuspended in 0.4 L
of Lysis buffer (20 mM sodium phosphate, pH 8.5, 1 mM EDTA) using a
Polytron.TM. homogenizer to achieve a homogenous suspension. The
cells were lysed by passing two times through a microfluidizer at
>15,000 psi. The lysed cell suspension was then centrifuged at
13,000.times.g for 10 minutes. Ammonium sulfate was added to the
supernatant to achieve 30% saturation. The suspension was stirred
at room temperature for 10 minutes and then centrifuged at
13,000.times.g for 15 minutes. Ammonium sulfate was added to the
supernatant to 64% saturation and the solution was stirred at room
temperature for 10 minutes and the solution was then centrifuged at
13,000.times.g for 15 minutes. The pellet was resuspended in 0.4 L
of Diafiltration buffer (20 mM sodium phosphate buffer, pH 8.5) and
diafiltered against 5 volumes of Diafiltration Buffer using a
filter with a 50,000 MW cutoff. The diafiltered solution was then
applied to a Poros HQ50 column previously equilibrated with Column
Buffer (20 mM sodium phosphate buffer, pH 8.5). The column was
washed with Column Buffer and the flow through collected. The flow
through material was then applied to a BioRad HA column
equilibrated with Column Buffer. The HA column was washed with 10
volumes of Column Buffer and the uricase eluted by running a
gradient from 100% Column Buffer to 100% 0.5 M sodium phosphate, pH
8.5. The eluted uricase was again passed over a Poros HQ column
equilibrated with Column Buffer. The flow through fraction
containing the uricase was collected and stored at 4.degree. C.
Example 4
Characterization of Purified Uricase
[0090] Uricase Assay
[0091] Uricase activity was assayed using the uric acid diagnostic
kit from Sigma (St. Louis, Mo.). The specific activity of the
enzyme was determined by incubating the enzyme with uric acid and
monitoring the production of hydrogen peroxide. The production of
hydrogen peroxide is determined by reaction with 4-aminoantipyrine
and 3,5-dichloro-2-hydroxyb- enzenesulfonate in the presence of
peroxidase. A quinoeimine dye is formed with an absorbance maximum
at 520 nm. The intensity of the color produced is directly
proportional to the amount of hydrogen peroxide formed. The amount
of hydrogen peroxide formed is determined by comparison with
standards containing known amounts of hydrogen peroxide. Specific
Enzyme activity=nmol of hydrogen peroxide produced/min/mg of
protein in the assay. Enzyme activity is expressed in IU/mL. 1 IU
is defined as that amount of enzyme which produces 1 nmol of
hydrogen peroxide/min.
[0092] SDS-PAGE
[0093] The expression level of the uricase was determined by
SDS-PAGE. Samples (1 ml) from the 20 L fermentation culture were
taken prior to the IPTG induction (pre-induction sample) of the
uricase expression, and 2 hours following the addition of IPTG
(post-induction sample). These samples were quickly centrifuged in
a micro-centrifuge (12,000.times.g for 1 min) then frozen at
-70.degree. C. The frozen cell pellet of was resuspended in 1 ml of
water and sonicated for 15 sec with a probe sonicator. The
resulting sonicate was electrophoresed on a 10-20% SDS-PAGE gel run
under reducing conditions. The gels were stained using Coomassie
Blue.
Example 5
Pegylation
[0094] Pegylation of Uricase with PEG-5,000
[0095] Purified uricase in Column Buffer (20 mM sodium phosphate
buffer, pH 8.5) was pegylated with methoxy-SS-polyethyleneglycol MW
5,000 at a ratio of PEG to uricase of 30:1 (wt/wt). The PEG 5000
was added to the uricase solution and stirred for 1 hour at room
temperature. The conjugated uricase-PEG 5000 was concentrated by
diafiltration to approximately {fraction (1/10)} volume and then
diafiltered against 10 volumes of Formulation Buffer (20 mM sodium
phosphate buffer, pH 6.8, 130 mM sodium chloride).
[0096] Pegylation of Uricase with PEG-20,000
[0097] Purified uricase in Column Buffer (20 mM sodium phosphate
buffer, pH 8.5) was pegylated with methoxy-SS-polyethyleneglycol
MW-20,000 at a ratio of PEG to uricase of 30:1 (wt/wt). The PEG
20000 was added to the uricase solution and stirred for 2 hours at
room temperature. The conjugated uricase-PEG-20000 was concentrated
by diafiltration to approximately {fraction (1/10)} volume and then
diafiltered against 10 volumes of Formulation Buffer (20 mM sodium
phosphate buffer, pH 6.8, 130 mM sodium chloride).
Example 6
Characterization of Pegylated Protein
[0098] SDS-PAGE
[0099] The purity of the pegylated uricase and extent of pegylation
was examined by SDS-PAGE. Samples from the pegylation reactions
were electrophoesed on a 10-20% SDS-PAGE gel run under reducing
conditions. The gels were stained using Coomassie Blue.
[0100] Uricase Assay
[0101] The enzymatic activity of the pegylated uricases was
determined using the uricase assay described in Example 4. Specific
Enzyme activity=nmol of hydrogen peroxide produced/min.)/mg of
protein in the assay. Enzyme activity is expressed in IU/mL. 1 IU
is defined as that amount of enzyme which produces 1 nmol of
hydrogen peroxide/min.
[0102] PEG Number
[0103] The trinitrobenzenesulfonic acid (TNBS) assay (Habeeb, A. F.
S. A. Analyt. Biochem. 14, 328-336 (1966)) was used to determine
the average number of polyethylene glycol molecules covalently
attached to primary amines in each uricase protein (PEG number).
TNBS reacts with the primary amine groups and results in a color
change. Protein that has been pegylated is compared to protein that
has not been pegylated.
[0104] Each protein sample was assayed at three different protein
concentrations. Each concentration was assayed in duplicate. The
protein concentration of each sample was adjusted to 0.2, 0.4 and
0.8 mg/mL with nanopure water and vortexed for 3 to 5 seconds. 0.25
mL of each protein sample was added into a 10.times.75 mm glass
tube. 0.25 mL of 4% sodium bicarbonate was added to each tube
followed by 0.25 mL of 0.1% TNBS. Tubes were incubated for 2 hours
at 40.degree. C. The tubes were then removed from the heating block
and 0.25 mL of 10% sodium dodecyl sulfate (SDS) added to each tube
followed by 0.125 mL of 1N HCl. The absorbance of each reaction was
measured at 335 .mu.m. The absorbances of the protein samples were
plotted and linear regression was performed to determine the slope
of the line. The number of primary amine residues pegylated was
determined by the following formula:
Number of primary amines pegylated=1-(slope of pegylated
protein/slope of unpegylated protein).times.total number of primary
amine residues in the protein
5TABLE 1 Comparison of native uricase and Uricase-PEG formulations.
Uricase-PEG 20 Native Uricase Uricase-PEG 5 Method B Purity >98%
>98% >98% Specific Activity 10.4 IU/mg 5.8 IU/mg 7.8 IU/mg
Circulating Half- .about.4 hours 6 hours 3 days Life PEG Number Not
applicable 19 19
[0105] A comparison of different uricase PEG formulations (Table 1)
shows that the uricase-PEG-20,000 retains a higher specific
activity than the uricase-PEG-5,000 even though the same average
number of PEG molecules are attached to the protein. Uricase-PEG
20,000 retains 75% of the specific activity of the native enzyme,
while uricase-PEG 5,000 retains only 56% of the native enzyme's
activity. This means that less of the uricase-PEG 20,000 can be
used to produce a given enzymatic activity than would be required
if uricase-PEG 5,000 were being used. However, the enzymatic
activity of uricase-PEG failed to increase relative to PEG-20,000
when PEGs larger than 20,000 were covalently bonded to uricase.
[0106] Further, the average molecular weight of the PEG covalently
bonded to uricase also plays an important role in determining both
circulating half-life and production yield. The yield of
uricase-PEG increases with increasing average molecular weight of
the bound polyethylene glycol as the average molecular weight of
the PEGs increases up to PEG-20,000. However, when PEG's with an
average molecular weight over 20,000 were used, the yield of
uricase-PEG decreased significantly. For example, when uricase is
bound to PEG-20,000, the relative yield is 1.0. When uricase is
bound to PEG-5,000, the relative yield is about 0.5. When uricase
is bound to PEG-10,000, the relative yield is about 0.66. When
uricase is bound to PEG-40,000, the relative yield drops to about
0.1.
Example 9
Application to Humans
[0107] The circulating half life of PEG conjugated uricase has a
circulating half life that is 5 to 10 times longer than the same
formulations in mice. What this has meant in the past is that the
human dose is most often 1/5 to {fraction (1/10)} of that used in
mice. Accordingly, the circulating half-life of PEG-uricase should
circulate even longer in humans than it does in mice.
[0108] Each of the patents, patent applications and publications
described herein are hereby incorporated by reference herein in
their entirety.
[0109] Various modifications of the invention, in addition to those
described herein, will be apparent to one skilled in the art in
view of the foregoing description. Such modifications are also
intended to fall within the scope of the appended claims.
Sequence CWU 1
1
6 1 30 DNA Artificial Primer 1 gtgtacgtaa tgtcaacaac gctctcatca 30
2 31 DNA Artificial Primer 2 agaaagcttt taccacttgg tcttctcctt a 31
3 5740 DNA Artificial Plasmid 3 ctcgagaaat cataaaaaat ttatttgctt
tgtgagcgga taacaattat aatagattca 60 attgtgagcg gataacaatt
tcacacagaa ttcattaaag aggagaaatt aagatgtcaa 120 caacgctctc
atcatccact tacggcaagg acaacgtcaa gttcctcaag gtcaagaagg 180
atccgcagaa cccaaagaag caggaggtta tggaggccac cgtcacgtgt ctgcttgaag
240 gtgggttcga cacctcctac acggaggctg acaactcgtc catcgtgcca
acagacaccg 300 tgaagaacac cattctcgtg ttggcaaaga ccacggagat
ttggccaatt gagagatttg 360 cagccaagct ggctacgcac tttgttgaga
agtactcgca cgtctctggt gtctccgtca 420 agattgtcca ggacagatgg
gtcaagtacg ccgttgatgg caagccacac gaccactctt 480 ttatccacga
aggtggtgag aagagaatca ctgacctgta ctacaagaga tccggtgatt 540
acaagctgtc atctgccatc aaggacttga cggtgctgaa gtccaccggc tcgatgttct
600 acggctacaa caagtgtgac ttcaccacct tgcaaccaac cactgacaga
atcttgtcca 660 ccgacgtcga tgccacctgg gtttgggata acaagaagat
tggcactgtc tacgacatcg 720 ccaaggctgc agacaagggg atctttgaca
acgtttacaa ccaggctaga gagatcacct 780 tgaccacctt cgccctggag
aactctccat ctgtgcaggc cacgatgttc aacatggcta 840 ctcagatctt
ggaaaaggca tgctctgtct actcggtttc atacgccttg ccaaacaagc 900
actacttcct cattgacttg aaatggaaag gtttggagaa cgacaacgag ttgttctacc
960 catctccaca tccaaatggt ttgatcaagt gtactgttgt ccgtaaggag
aagaccaagt 1020 tgtaaaagct tagcttaatt agctgagctt ggactcctgt
tgatagatcc agtaatgacc 1080 tcagaactcc atctggattt gttcagaacg
ctcggttgcc gccgggcgtt ttttattggt 1140 gagaatccaa gctagcttgg
cgagattttc aggagctaag gaagctaaaa tggagaaaaa 1200 aatcactgga
tataccaccg ttgatatatc ccaatggcat cgtaaagaac attttgaggc 1260
atttcagtca gttgctcaat gtacctataa ccagaccgtt cagctggata ttacggcctt
1320 tttaaagacc gtaaagaaaa ataagcacaa gttttatccg gcctttattc
acattcttgc 1380 ccgcctgatg aatgctcatc cggaatttcg tatggcaatg
aaagacggtg agctggtgat 1440 atgggatagt gttcaccctt gttacaccgt
tttccatgag caaactgaaa cgttttcatc 1500 gctctggagt gaataccacg
acgatttccg gcagtttcta cacatatatt cgcaagatgt 1560 ggcgtgttac
ggtgaaaacc tggcctattt ccctaaaggg tttattgaga atatgttttt 1620
cgtctcagcc aatccctggg tgagtttcac cagttttgat ttaaacgtgg ccaatatgga
1680 caacttcttc gcccccgttt tcaccatggg caaatattat acgcaaggcg
acaaggtgct 1740 gatgccgctg gcgattcagg ttcatcatgc cgtctgtgat
ggcttccatg tcggcagaat 1800 gcttaatgaa ttacaacagt actgcgatga
gtggcagggc ggggcgtaat ttttttaagg 1860 cagttattgg tgcccttaaa
cgcctggggt aatgactctc tagcttgagg catcaaataa 1920 aacgaaaggc
tcagtcgaaa gactgggcct ttcgttttat ctgttgtttg tcggtgaacg 1980
ctctcctgag taggacaaat ccgccgctct agaattctca tgtttgacag cttatcatcg
2040 ataagcttta atgcggtagt ttatcacagt taaattgcta acgcagtcag
gcaccgtgta 2100 tgaaatctaa caatgcgctc atcgtcatcc tcggcaccgt
caccctggat gctgtaggca 2160 taggcttggt tatgccggta ctgccgggcc
tcttgcggga tatcgtccat tccgacagca 2220 tcgccagtca ctatggcgtg
ctgctagcgc tatatgcgtt gatgcaattt ctatgcgcac 2280 ccgttctcgg
agcactgtcc gaccgctttg gccgccgccc agtcctgctc gcttcgctac 2340
ttggagccac tatcgactac gcgatcatgg cgaccacacc cgtcctgtgg atcctctacg
2400 ccggacgcat cgtggccggc atcaccggcg ccacaggtgc ggttgctggc
gcctatatcg 2460 ccgacatcac cgatggggaa gatcgggctc gccacttcgg
gctcatgagc gcttgtttcg 2520 gcgtgggtat ggtggcaggc cccgtggccg
ggggactgtt gggcgccatc tccttgcatg 2580 caccattcct tgcggcggcg
gtgctcaacg gcctcaacct actactgggc tgcttcctaa 2640 tgcaggagtc
gcataaggga gagcgtcgac cgatgccctt gagagccttc aacccagtca 2700
gctccttccg gtgggcgcgg ggcatgacta tcgtcgccgc acttatgact gtcttcttta
2760 tcatgcaact cgtaggacag gtgccggcag cgctctgggt cattttcggc
gaggaccgct 2820 ttcgctggag cgcgacgatg atcggcctgt cgcttgcggt
attcggaatc ttgcacgccc 2880 tcgctcaagc cttcgtcact ggtcccgcca
ccaaacgttt cggcgagaag caggccatta 2940 tcgccggcat ggcggccgac
gcgctgggct acgtcttgct ggcgttcgcg acgcgaggct 3000 ggatggcctt
ccccattatg attcttctcg cttccggcgg catcgggatg cccgcgttgc 3060
aggccatgct gtccaggcag gtagatgacg accatcaggg acagcttcaa ggatcgctcg
3120 cggctcttac cagcctaact tcgatcactg gaccgctgat cgtcacggcg
atttatgccg 3180 cctcggcgag cacatggaac gggttggcat ggattgtagg
cgccgcccta taccttgtct 3240 gcctccccgc gttgcgtcgc ggtgcatgga
gccgggccac ctcgacctga atggaagccg 3300 gcggcacctc gctaacggat
tcaccactcc aagaattgga gccaatcaat tcttgcggag 3360 aactgtgaat
gcgcaaacca acccttggca gaacatatcc atcgcgtccg ccatctccag 3420
cagccgcacg cggcgcatct cgctagagct gcctcgcgcg tttcggtgat gacggtgaaa
3480 acctctgaca catgcagctc ccggagacgg tcacagcttg tctgtaagcg
gatgccggga 3540 gcagacaagc ccgtcagggc gcgtcagcgg gtgttggcgg
gtgtcggggc gcagccatga 3600 cccagtcacg tagcgatagc ggagtgtata
ctggcttaac tatgcggcat cagagcagat 3660 tgtactgaga gtgcaccata
tgcggtgtga aataccgcac agatgcgtaa ggagaaaata 3720 ccgcatcagg
cgctcttccg cttcctcgct cactgactcg ctgcgctcgg tctgtcggct 3780
gcggcgagcg gtatcagctc actcaaaggc ggtaatacgg ttatccacag aatcagggga
3840 taacgcagga aagaacatgt gagcaaaagg ccagcaaaag gccaggaacc
gtaaaaaggc 3900 cgcgttgctg gcgtttttcc ataggctccg cccccctgac
gagcatcaca aaaatcgacg 3960 ctcaagtcag aggtggcgaa acccgacagg
actataaaga taccaggcgt ttccccctgg 4020 aagctccctc gtgcgctctc
ctgttccgac cctgccgctt accggatacc tgtccgcctt 4080 tctcccttcg
ggaagcgtgg cgctttctca atgctcacgc tgtaggtatc tcagttcggt 4140
gtaggtcgtt cgctccaagc tgggctgtgt gcacgaaccc cccgttcagc ccgaccgctg
4200 cgccttatcc ggtaactatc gtcttgagtc caacccggta agacacgact
tatcgccact 4260 ggcagcagcc actggtaaca ggattagcag agcgaggtat
gtaggcggtg ctacagagtt 4320 cttgaagtgg tggcctaact acggctacac
tagaaggaca gtatttggta tctgcgctct 4380 gctgaagcca gttaccttcg
gaaaaagagt tggtagctct tgatccggca aacaaaccac 4440 cgctggtagc
ggtggttttt ttgtttgcaa gcagcagatt acgcgcagaa aaaaaggatc 4500
tcaagaagat cctttgatct tttctacggg gtctgacgct cagtggaacg aaaactcacg
4560 ttaagggatt ttggtcatga gattatcaaa aaggatcttc acctagatcc
ttttaaatta 4620 aaaatgaagt tttaaatcaa tctaaagtat atatgagtaa
acttggtctg acagttacca 4680 atgcttaatc agtgaggcac ctatctcagc
gatctgtcta tttcgttcat ccatagctgc 4740 ctgactcccc gtcgtgtaga
taactacgat acgggagggc ttaccatctg gccccagtgc 4800 tgcaatgata
ccgcgagacc cacgctcacc ggctccagat ttatcagcaa taaaccagcc 4860
agccggaagg gccgagcgca gaagtggtcc tgcaacttta tccgcctcca tccagtctat
4920 taattgttgc cgggaagcta gagtaagtag ttcgccagtt aatagtttgc
gcaacgttgt 4980 tgccattgct acaggcatcg tggtgtcacg ctcgtcgttt
ggtatggctt cattcagctc 5040 cggttcccaa cgatcaaggc gagttacatg
atcccccatg ttgtgcaaaa aagcggttag 5100 ctccttcggt cctccgatcg
ttgtcagaag taagttggcc gcagtgttat cactcatggt 5160 tatggcagca
ctgcataatt ctcttactgt catgccatcc gtaagatgct tttctgtgac 5220
tggtgagtac tcaaccaagt cattctgaga atagtgtatg cggcgaccga gttgctcttg
5280 cccggcgtca atacgggata ataccgcgcc acatagcaga actttaaaag
tgctcatcat 5340 tggaaaacgt tcttcggggc gaaaactctc aaggatctta
ccgctgttga gatccagttc 5400 gatgtaaccc actcgtgcac ccaactgatc
ttcagcatct tttactttca ccagcgtttc 5460 tgggtgagca aaaacaggaa
ggcaaaatgc cgcaaaaaag ggaataaggg cgacacggaa 5520 atgttgaata
ctcatactct tcctttttca atattattga agcatttatc agggttattg 5580
tctcatgagc ggatacatat ttgaatgtat ttagaaaaat aaacaaatag gggttccgcg
5640 cacatttccc cgaaaagtgc cacctgacgt ctaagaaacc attattatca
tgacattaac 5700 ctataaaaat aggcgtatca cgaggccctt tcgtcttcac 5740 4
912 DNA Candida utilis CDS (1)..(909) 4 atg tca aca acg ctc tca tca
tcc act tac ggc aag gac aac gtc aag 48 Met Ser Thr Thr Leu Ser Ser
Ser Thr Tyr Gly Lys Asp Asn Val Lys 1 5 10 15 ttc ctc aag gtc aag
aag gat ccg cag aac cca aag aag cag gag gtt 96 Phe Leu Lys Val Lys
Lys Asp Pro Gln Asn Pro Lys Lys Gln Glu Val 20 25 30 atg gag gcc
acc gtc acg tgt ctg ctt gaa ggt ggg ttc gac acc tcc 144 Met Glu Ala
Thr Val Thr Cys Leu Leu Glu Gly Gly Phe Asp Thr Ser 35 40 45 tac
acg gag gct gac aac tcg tcc atc gtg cca aca gac acc gtg aag 192 Tyr
Thr Glu Ala Asp Asn Ser Ser Ile Val Pro Thr Asp Thr Val Lys 50 55
60 aac acc att ctc gtg ttg gca aag acc acg gag att tgg cca att gag
240 Asn Thr Ile Leu Val Leu Ala Lys Thr Thr Glu Ile Trp Pro Ile Glu
65 70 75 80 aga ttt gca gcc aag ctg gct acg cac ttt gtt gag aag tac
tcg cac 288 Arg Phe Ala Ala Lys Leu Ala Thr His Phe Val Glu Lys Tyr
Ser His 85 90 95 gtc tct ggt gtc tcc gtc aag att gtc cag gac aga
tgg gtc aag tac 336 Val Ser Gly Val Ser Val Lys Ile Val Gln Asp Arg
Trp Val Lys Tyr 100 105 110 gcc gtt gat ggc aag cca cac gac cac tct
ttt atc cac gaa ggt ggt 384 Ala Val Asp Gly Lys Pro His Asp His Ser
Phe Ile His Glu Gly Gly 115 120 125 gag aag aga atc act gac ctg tac
tac aag aga tcc ggt gat tac aag 432 Glu Lys Arg Ile Thr Asp Leu Tyr
Tyr Lys Arg Ser Gly Asp Tyr Lys 130 135 140 ctg tca tct gcc atc aag
gac ttg acg gtg ctg aag tcc acc ggc tcg 480 Leu Ser Ser Ala Ile Lys
Asp Leu Thr Val Leu Lys Ser Thr Gly Ser 145 150 155 160 atg ttc tac
ggc tac aac aag tgt gac ttc acc acc ttg caa cca acc 528 Met Phe Tyr
Gly Tyr Asn Lys Cys Asp Phe Thr Thr Leu Gln Pro Thr 165 170 175 act
gac aga atc ttg tcc acc gac gtc gat gcc acc tgg gtt tgg gat 576 Thr
Asp Arg Ile Leu Ser Thr Asp Val Asp Ala Thr Trp Val Trp Asp 180 185
190 aac aag aag att ggc act gtc tac gac atc gcc aag gct gca gac aag
624 Asn Lys Lys Ile Gly Thr Val Tyr Asp Ile Ala Lys Ala Ala Asp Lys
195 200 205 ggg atc ttt gac aac gtt tac aac cag gct aga gag atc acc
ttg acc 672 Gly Ile Phe Asp Asn Val Tyr Asn Gln Ala Arg Glu Ile Thr
Leu Thr 210 215 220 acc ttc gcc ctg gag aac tct cca tct gtg cag gcc
acg atg ttc aac 720 Thr Phe Ala Leu Glu Asn Ser Pro Ser Val Gln Ala
Thr Met Phe Asn 225 230 235 240 atg gct act cag atc ttg gaa aag gca
tgc tct gtc tac tcg gtt tca 768 Met Ala Thr Gln Ile Leu Glu Lys Ala
Cys Ser Val Tyr Ser Val Ser 245 250 255 tac gcc ttg cca aac aag cac
tac ttc ctc att gac ttg aaa tgg aaa 816 Tyr Ala Leu Pro Asn Lys His
Tyr Phe Leu Ile Asp Leu Lys Trp Lys 260 265 270 ggt ttg gag aac gac
aac gag ttg ttc tac cca tct cca cat cca aat 864 Gly Leu Glu Asn Asp
Asn Glu Leu Phe Tyr Pro Ser Pro His Pro Asn 275 280 285 ggt ttg atc
aag tgt act gtt gtc cgt aag gag aag acc aag ttg taa 912 Gly Leu Ile
Lys Cys Thr Val Val Arg Lys Glu Lys Thr Lys Leu 290 295 300 5 303
PRT Candida utilis 5 Met Ser Thr Thr Leu Ser Ser Ser Thr Tyr Gly
Lys Asp Asn Val Lys 1 5 10 15 Phe Leu Lys Val Lys Lys Asp Pro Gln
Asn Pro Lys Lys Gln Glu Val 20 25 30 Met Glu Ala Thr Val Thr Cys
Leu Leu Glu Gly Gly Phe Asp Thr Ser 35 40 45 Tyr Thr Glu Ala Asp
Asn Ser Ser Ile Val Pro Thr Asp Thr Val Lys 50 55 60 Asn Thr Ile
Leu Val Leu Ala Lys Thr Thr Glu Ile Trp Pro Ile Glu 65 70 75 80 Arg
Phe Ala Ala Lys Leu Ala Thr His Phe Val Glu Lys Tyr Ser His 85 90
95 Val Ser Gly Val Ser Val Lys Ile Val Gln Asp Arg Trp Val Lys Tyr
100 105 110 Ala Val Asp Gly Lys Pro His Asp His Ser Phe Ile His Glu
Gly Gly 115 120 125 Glu Lys Arg Ile Thr Asp Leu Tyr Tyr Lys Arg Ser
Gly Asp Tyr Lys 130 135 140 Leu Ser Ser Ala Ile Lys Asp Leu Thr Val
Leu Lys Ser Thr Gly Ser 145 150 155 160 Met Phe Tyr Gly Tyr Asn Lys
Cys Asp Phe Thr Thr Leu Gln Pro Thr 165 170 175 Thr Asp Arg Ile Leu
Ser Thr Asp Val Asp Ala Thr Trp Val Trp Asp 180 185 190 Asn Lys Lys
Ile Gly Thr Val Tyr Asp Ile Ala Lys Ala Ala Asp Lys 195 200 205 Gly
Ile Phe Asp Asn Val Tyr Asn Gln Ala Arg Glu Ile Thr Leu Thr 210 215
220 Thr Phe Ala Leu Glu Asn Ser Pro Ser Val Gln Ala Thr Met Phe Asn
225 230 235 240 Met Ala Thr Gln Ile Leu Glu Lys Ala Cys Ser Val Tyr
Ser Val Ser 245 250 255 Tyr Ala Leu Pro Asn Lys His Tyr Phe Leu Ile
Asp Leu Lys Trp Lys 260 265 270 Gly Leu Glu Asn Asp Asn Glu Leu Phe
Tyr Pro Ser Pro His Pro Asn 275 280 285 Gly Leu Ile Lys Cys Thr Val
Val Arg Lys Glu Lys Thr Lys Leu 290 295 300 6 303 PRT Candida
utilis 6 Met Ser Thr Thr Leu Ser Ser Ser Thr Tyr Gly Lys Asp Asn
Val Lys 1 5 10 15 Phe Leu Lys Val Lys Lys Asp Pro Gln Asn Pro Lys
Lys Gln Glu Val 20 25 30 Met Glu Ala Thr Val Thr Cys Leu Leu Glu
Gly Gly Phe Asp Thr Ser 35 40 45 Tyr Thr Glu Ala Asp Asn Ser Ser
Ile Val Pro Thr Asp Thr Val Lys 50 55 60 Asn Thr Ile Leu Val Leu
Ala Lys Thr Thr Glu Ile Trp Pro Ile Glu 65 70 75 80 Arg Phe Ala Ala
Lys Leu Ala Thr His Phe Val Glu Lys Tyr Ser His 85 90 95 Val Ser
Gly Val Ser Val Lys Ile Val Gln Asp Arg Trp Val Lys Tyr 100 105 110
Ala Val Asp Gly Lys Pro His Asp His Ser Phe Ile His Glu Gly Gly 115
120 125 Glu Lys Arg Ile Thr Asp Leu Tyr Tyr Lys Arg Ser Gly Asp Tyr
Lys 130 135 140 Leu Ser Ser Ala Ile Lys Asp Leu Thr Val Leu Lys Ser
Thr Gly Ser 145 150 155 160 Met Phe Tyr Gly Tyr Asn Lys Cys Asp Phe
Thr Thr Leu Gln Pro Thr 165 170 175 Thr Asp Arg Ile Leu Ser Thr Asp
Val Asp Ala Thr Trp Val Trp Asp 180 185 190 Asn Lys Lys Ile Gly Thr
Val Tyr Asp Ile Ala Lys Ala Ala Asp Lys 195 200 205 Gly Ile Phe Asp
Asn Val Tyr Asn Gln Ala Arg Glu Ile Thr Leu Thr 210 215 220 Thr Phe
Ala Leu Glu Asn Ser Pro Ser Val Gln Ala Thr Met Phe Asn 225 230 235
240 Met Ala Thr Gln Ile Leu Glu Lys Ala Cys Ser Val Tyr Ser Val Ser
245 250 255 Tyr Ala Leu Pro Asn Lys His Tyr Phe Leu Ile Asp Leu Lys
Trp Lys 260 265 270 Gly Leu Glu Asn Asp Asn Glu Leu Phe Tyr Pro Ser
Pro His Pro Asn 275 280 285 Gly Leu Ile Lys Cys Thr Val Val Arg Lys
Glu Lys Thr Lys Leu 290 295 300
* * * * *