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Modified vitamin K-dependent polypeptides

Inactive Publication Date: 2006-11-23
RGT UNIV OF MINNESOTA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0009] It has been discovered that modifications within the γ-carboxyglutamic acid (GLA) domain of vitamin K-dependent polypeptides enhance their membrane binding affinities. Vitamin K-dependent polypeptides modified in such a manner have enhanced activity and may be used as anti-coagulants, pro-coagulants, or for other functions that utilize vitamin K-dependent proteins. For example, an improved factor VII molecule may provide several benefits by lowering the dosage of VIIa needed, reducing the relative frequency of administration and / or by providing qualitative changes that allow more effective treatment of deficiency states.
[0010] The invention features vitamin K-dependent polypeptides that include a modified GLA domain that enhances membrane-binding affinity of the polypeptide relative to a corresponding native vitamin K-dependent polypeptide. In some embodiments, activity of the vitamin K-dependent polypeptide also is enhanced. The modified GLA domain can be from about amino acid 1 to about amino acid 45 and can include at least one amino acid substitution. For example, the amino acid substitution can be at amino acid 2, 5, 9, 11, 12, 29, 33, 34, 35, or 36, and combinations thereof. In particular, the substitution can be at amino acid 34, amino acids 11, 12, 29, 33, or 34, amino acids 2, 5, or 9, amino acids 11 or 12, amino acids 29 or 33, or amino acids 34, 35, or 36. The modified GLA domain may include an amino acid sequence, which, in the calcium saturated state, forms a tertiary structure having a cationic core with a halo of electronegative charge.
[0017] The invention also relates to a pharmaceutical composition that includes a pharmaceutically acceptable carrier and an amount of a vitamin K-dependent polypeptide effective to inhibit clot formation in a mammal. The vitamin K-dependent polypeptide includes a modified GLA domain that enhances membrane-binding affinity of the polypeptide relative to a corresponding native vitamin K-dependent polypeptide. In some embodiments, activity of the polypeptide also is enhanced. The modified GLA domain includes at least one amino acid substitution (e.g., a glutamic acid residue substituted at position 34). The vitamin K-dependent polypeptide may be, for example, protein C, activated protein C or active site modified factor VIIa, protein S, or active site modified factor IXa. The composition can include an anticoagulant agent (e.g. aspirin).
[0019] A method of decreasing clot formation in a mammal is also described. The method includes administering an amount of a vitamin K-dependent polypeptide effective to decrease clot formation in the mammal. The vitamin K-dependent polypeptide includes a modified GLA domain that enhances membrane-binding affinity of the polypeptide relative to a corresponding native vitamin K-dependent polypeptide. In some embodiments, activity of the polypeptide also is enhanced. The modified GLA domain includes at least one amino acid substitution (e.g., a glutamic acid substituted at position 34). The vitamin K-dependent polypeptide may be, for example, protein C, activated protein C or active site modified factor VIIa or factor IXa, or protein S.
[0021] In another aspect, the invention features a method for identifying a vitamin K-dependent polypeptide having enhanced membrane binding affinity and activity. The method includes modifying the GLA domain of the polypeptide, wherein modifying includes substituting at least one amino acid in the GLA domain; monitoring membrane binding affinity and activity of the polypeptide having the modified GLA domain; and identifying the modified vitamin K-dependent polypeptide as having enhanced membrane binding affinity and activity if membrane binding affinity activity of the modified polypeptide is enhanced relative to a corresponding native vitamin K-dependent polypeptide. Suitable substitutions are described above. The polypeptide can increase clot formation or inhibit clot formation.

Problems solved by technology

Factor VIII replacement therapy is limited due to development of high-titer inhibitory factor VIII antibodies in some patients.

Method used

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Examples

Experimental program
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example 1

Factor VII with Enhanced Membrane Affinity and Activity

[0086] It has been found that the membrane binding affinity of human blood clotting factor VII can be increased by site-directed mutagenesis. The properties of a P11IQ,K33E mutant (referred to herein as Factor VIIQ11E33 or mutant factor VII) have been characterized. Membrane affinity was increased over wild type protein by about 20-fold. Autoactivation by the mutant was increased by at least 100-fold over that of wild type factor VII. The activated form of VIIQ11E33 (referred to as VIIaQ11E33) displayed about 10-fold higher activity toward factor X. The coagulation activity of VIIaQ11E33 with soluble tissue factor in normal plasma was about 10-fold higher than that of wild type VIIa. Coagulation activity of the zymogen, VIIQ11E33, with normal tissue factor (supplied as a 1:100 dilution of thromboplastin-HS), was 20-fold higher than wild type Factor VII. The degree to which activity was enhanced was dependent on conditions, with...

example 2

Purification of Factor VII

[0112] Factor VII (wild-type or mutant) was purified by Concanavalin A (Con A), DEAE, and affinity chromatography. Crude media of transfected 293 cells were incubated with Con A resin (Pharmacia) for four hours at 4° C. The resin then was washed with a solution containing 50 mM Tris, pH 7.5, 10 mM benzamidine, 1 mM CaCl2, and 1 mM MgCl2, and factor VII was eluted with 0.2 M D-methyl mannoside, 0.5 M NaCl in 50 mM Tris buffer, pH 7.5. Factor VII was dialyzed against 50 mM Tris, pH 8.0, 50 mM NaCl, 10 mM benzamidine, and 25 mM D-methyl mannoside overnight.

[0113] Dialyzed factor VII then was incubated with DEAE resin (Pharmacia) for one hour and the mixture was packed into a column. The DEAE column was washed with 50 mM Tris, pH 8.0, 10 mM Benzamidine, and 50 mM NaCl, and factor VII was eluted with a gradient from 50 mM to 500 mM NaCl in 50 mM Tris buffer, pH 8.0 at a flow rate of 2 mL / min. Fractions containing factor VII activity were pooled and dialyzed ag...

example 3

Circulatory Time of Factor VIIQ11E33 in the Rat

[0122] Two anesthetized (sodium nembutol) Sprague Dawley rats (325-350 g) were injected with 36 μg of factor VIIQ11E33 at time zero. Injection was through the juggler vein, into which a cannula had been placed. At the times shown in FIG. 7, blood was withdrawn from the carotid artery, into which a cannula had been inserted by surgery. The amount of factor VIIQ11E33 in the circulation was estimated from the clotting time of human factor VII-deficient plasma, to which 1 μL of a 1:10 dilution of the rat plasma was added. A 1:100 dilution of rabbit brain thromboplastin-HS (Sigma Chemical Co.) was used. Coagulation was assessed by the manual tube tilt method as described in Example 1. The amount of factor VII activity in the plasma before injection of VIIQ11E33 was determined and was subtracted as a blank. The concentration of factor VIIQ11E33 in the circulation is given as log nM. A sham experiment in which a third animal received the oper...

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Abstract

The invention provides vitamin K-dependent polypeptides with enhanced membrane binding affinity. These polypeptides can be used to modulate clot formation in mammals. Methods of modulating clot formation in mammals are also described.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. Ser. No. 10 / 298,330, filed Nov. 18, 2002, which is a continuation-in-part of U.S. Ser. No. 09 / 497,591, filed Feb. 3, 2000, now U.S. Pat. No. 6,747,003, which is a continuation-in-part of U.S. Ser. No. 09 / 302,239, filed on Apr. 29, 1999, now U.S. Pat. No. 6,693,075, which is a continuation-in-part of U.S. Ser. No. 08 / 955,636, filed on Oct. 23, 1997, now U.S. Pat. No. 6,017,882.STATEMENT AS TO FEDERALLY-SPONSORED RESEARCH [0002] Funding for work described herein was provided by the federal government, which has certain rights in the invention.BACKGROUND OF THE INVENTION [0003] Vitamin K-dependent proteins contain 9 to 13 gamma-carboxyglutamic acid residues (Gla) in their amino terminal 45 residues. The Gla residues are produced by enzymes in the liver that utilize vitamin K to carboxylate the side chains of glutamic acid residues in protein precursors. Vitamin K-dependent proteins are involved in...

Claims

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Application Information

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IPC IPC(8): A61K38/37C07K14/745C07H21/04C12P21/04A61K38/00C12N9/64
CPCA61K38/4846C07K14/745C12N9/647C07K14/47A61K45/00C07K14/00A61K38/16A61P7/04
Inventor NELSESTUEN, GARY
Owner RGT UNIV OF MINNESOTA
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