Methods of synthesizing insulin polypeptide-oligomer conjugates, and proinsulin polypeptide-oligomer conjugates and methods of synthesizing same

1. A method of synthesizing an insulin polypeptide-oligomer conjugate comprising:

contacting a proinsulin polypeptide comprising an insulin polypeptide coupled to one or more peptides by peptide bond(s) capable of being cleaved to yield the insulin polypeptide with an oligomer comprising the structure of Formula II:

A-X(CH 2 ) m Y(C 2 H 4 O) n R  (II)

wherein:

A is —C(O)—OH, C(S)—OH, —C(S)—SH, —OH, —SH, or NH 2 ;

X is an oxygen atom or a covalent bond, with the proviso that X is not an oxygen atom when A is —OH;

Y is an ester, an ether, a carbamate, a carbonate, or an amide bonding moiety;

m is between 1 and 30;

n is between 1 and 50; and

R is an alkyl moiety, a sugar moiety, cholesterol, adamantane, an alcohol moiety, or a fatty acid moiety;

under conditions sufficient to couple the oligomer to the insulin polypeptide portion of the proinsulin polypeptide and provide a proinsulin polypeptide-oligomer conjugate; and

cleaving the one or more peptides from the proinsulin polypeptide-oligomer conjugate to provide the insulin polypeptide-oligomer conjugate.

2. The method according to claim 1 , wherein the contacting of the proinsulin polypeptide to the oligomer comprises:

contacting the oligomer with an activating agent under conditions sufficient to provide an activated oligomer capable of coupling to a nucleophilic functionality on the proinsulin polypeptide; and

contacting the activated oligomer with the proinsulin polypeptide under conditions sufficient to provide the proinsulin polypeptide-oligomer conjugate.

3. The method according to claim 2 , wherein the contacting of the oligomer with the activating agent and the contacting of the activated oligomer with the proinsulin polypeptide is performed in situ.

4. The method according to claim 2 , wherein the molar ratio of activated oligomer to proinsulin polypeptide is greater than about 1:1.

5. The method according to claim 2 , wherein the molar ratio of activated oligomer to proinsulin polypeptide is greater than about 3:1.

6. The method according to claim 2 , wherein the molar ratio of activated oligomer to proinsulin polypeptide is greater than about 4:1.

7. The method according to claim 6 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 75 percent.

8. The method according to claim 6 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 80 percent.

9. The method according to claim 6 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 85 percent.

10. The method according to claim 6 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than about 90 percent.

11. The method according to claim 6 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than about 95 percent.

12. The method according to claim 1 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 75 percent.

13. The method according to claim 1 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 80 percent.

14. The method according to claim 1 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than 85 percent.

15. The method according to claim 1 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than about 90 percent.

16. The method according to claim 1 , wherein the yield of insulin polypeptide-oligomer conjugate is greater than about 95 percent.

17. The method according to claim 1 , wherein the insulin polypeptide has an A-chain polypeptide and a B-chain polypeptide, and wherein the one or more peptides comprise a connecting peptide coupled at a first end to the C-terminus of the B-chain polypeptide and coupled at a second end to the N-terminus of the A-chain polypeptide.

18. The method according to claim 17 , wherein the connecting peptide is a C-peptide polypeptide.

19. The method according to claim 17 , wherein the connecting peptide is C-peptide.

20. The method according to claim 17 , wherein the connecting peptide is devoid of lysine residues.

21. The method according to claim 17 , wherein the one or more peptides further comprise a leader peptide coupled to the N-terminus of the B-chain polypeptide.

22. The method according to claim 21 , wherein the leader peptide is devoid of lysine residues.

23. The method according to claim 1 , wherein the proinsulin polypeptide is proinsulin.

24. The method according to claim 1 , wherein the proinsulin polypeptide is proinsulin coupled at the N-terminus of the B-chain to a leader peptide by a peptide bond that is cleavable.

25. The method according to claim 1 , wherein the insulin polypeptide is insulin.

26. The method according to claim 25 , wherein the oligomer is coupled to the lysine at the B29 position of the insulin.

27. The method according to claim 1 , wherein the insulin polypeptide-oligomer conjugate is amphiphilically balanced.

28. The method according to claim 1 , wherein the polyalkylene glycol moiety is a polyethylene glycol moiety.

29. The method according to claim 1 , wherein m is between 3 and 16.

30. The method according to claim 1 , wherein m is between 4 and 14.

31. The method according to claim 1 , wherein m is between 5 and 10.

32. The method according to claim 1 , wherein n is between 3 and 18.

33. The method according to claim 1 , wherein n is between 4 and 14.

34. The method according to claim 1 , wherein n is between 5 and 10.

35. The method according to claim 1 , wherein R is lower alkyl.

36. The method according to claim 1 , wherein R is C 1 to C 3 alkyl.

37. The method according to claim 1 , wherein R is methyl.

38. The method according to claim 1 , wherein the cleaving of the one or more peptides from the proinsulin polypeptide-oligomer conjugate comprises contacting the proinsulin polypeptide-oligomer conjugate with one or more enzymes that are capable of cleaving the bond(s) between the one or more peptides and the insulin polypeptide under conditions sufficient to cleave the one or more peptides from the proinsulin polypeptide-oligomer conjugate.

39. The method according to claim 38 , wherein the one or more enzymes are selected from the group consisting of trypsin, carboxy peptidase B, and mixtures thereof.

40. The method according to claim 17 , wherein the connecting peptide has a terminal amino acid residue at the first end, and wherein the cleaving of the connecting peptide from the proinsulin-oligomer conjugate comprises:

contacting the proinsulin polypeptide-oligomer conjugate with a first enzyme under conditions sufficient to provide a terminal amino acid residue-insulin polypeptide-oligomer conjugate; and

contacting the terminal amino acid residue-insulin polypeptide-oligomer conjugate with a second enzyme under conditions sufficient to provide the insulin-oligomer conjugate.

41. The method according to claim 40 , wherein the terminal amino acid residue is an arginine residue.

42. The method according to claim 41 , wherein the insulin polypeptide is insulin, and wherein the connecting peptide is human C-peptide.

43. The method according to claim 40 , wherein the contacting of the proinsulin-oligomer conjugate with a first enzyme and the contacting of the terminal amino acid residue-insulin polypeptide-oligomer conjugate with a second enzyme occur substantially concurrently.

44. The method according to claim 43 , wherein the first enzyme and the second enzyme are provided in a mixture comprising the first enzyme and the second enzyme.

45. The method according to claim 40 , wherein the first enzyme is trypsin, and wherein the second enzyme is carboxy peptidase B.