Recombinant factor VIII having increased specific activity
The present invention relates to recombinant factor VIII having a specific activity that is higher than that of the corresponding wild-type factor VIII. The present invention also relates to methods of making and using the recombinant factor VIII. The present invention also relates to an isolated nucleic acid molecule that encodes the recombinant factor VIII, as well as DNA expression systems and host cells containing the isolated nucleic acid molecule.
1. A recombinant factor VIII comprising an A1 domain having a calcium binding site according to one of SEQ ID NOS: 4-7 except for a substitution of the glutamic acid residue at the fourth residue of SEQ ID NOS: 4-7, wherein the recombinant factor VIII has a specific activity, as measured in a one-stage clotting assay, that is higher than that of a corresponding wild-type factor VIII.
2. The recombinant factor VIII according to claim 1 , wherein the substitution is selected from the group consisting of alanine, valine, isoleucine, leucine, asparagine, glycine, and methionine.
3. The recombinant factor VIII according to claim 1 , wherein the substitution is alanine.
4. The recombinant factor VIII according to claim 1 , wherein the recombinant factor VIII has a specific activity at least about twice as great as the activity of the wild-type factor VIII.
5. The recombinant factor VIII according to claim 1 , wherein the recombinant factor VIII is B domainless.
6. The recombinant factor VIII according to claim 1 , wherein the recombinant factor VIII has a circulating half-life value that is equivalent to or greater than that of the wild-type factor VIII.
7. The recombinant factor VIII according to claim 1 , wherein the recombinant factor VIII is substantially pure.
8. A pharmaceutical composition comprising the recombinant factor VIII according to claim 1 .
9. The pharmaceutical composition according to claim 8 further comprising a stabilizer.
10. The pharmaceutical composition according to claim 8 further comprising a delivery vehicle.
11. The pharmaceutical composition according to claim 8 further comprising a pharmaceutically acceptable carrier.
12. A method of treating an animal for hemophilia A, the method comprising:
administering to an animal exhibiting hemophilia A an effective amount of the recombinant factor VIII according to claim 1 , whereby the animal exhibits effective blood clotting following vascular injury.
13. The method according to claim 12 , wherein the effective amount comprises between about 10 to about 50 units/kg body weight of the animal.
14. The method according to claim 12 wherein the animal is a mammal.
15. The method according to claim 14 wherein the mammal is selected from the group consisting of human, rat, mouse, guinea pig, dog, cat, monkey, chimpanzee, orangutan, cow, horse, sheep, pig, goat, rabbit, and chicken.
16. The method according to claim 12 further comprising:
periodically repeating said administering.