N-terminal truncated insulin analogues
An insulin analogue contains a foreshortened B-chain polypeptide lacking residues B1-B3 and optionally contains an additional substitution in the C-terminal B23-B30 segment of the B-chain. The insulin analogue lacking residues B1-B3 may contain substitutions at B28 and/or B29 that confer rapid action and optionally a non-standard substitution at B24. The analogue may be an analogue of a mammalian insulin, such as human insulin. A nucleic acid encoding such an insulin analogue is also provided. A method of treating a patient comprises administering a physiologically effective amount of the insulin analogue or a physiologically acceptable salt thereof to a patient. A method of semi-synthesis is provided using an unprotected octapeptide by means of modification of an endogenous tryptic site by non-standard amino-acid substitutions.
1. A method for preparing a des-tripeptide [B1-B3] insulin analogue, the method comprising:
providing a folded single-chain or two-chain insulin-related precursor polypeptide containing Arg or Lys at position B3;
adding trypsin to the folded single-chain or two-chain insulin-related precursor polypeptide under conditions conducive to the proteolytic activity of trypsin to provide a reaction mixture;
incubating the reaction mixture for sufficient time to yield a des-tripeptide[B1-B3]-des-octapeptide [B23-B30]-insulin intermediate product;
adding a synthetic peptide in molar excess, wherein the synthetic peptide comprises residues corresponding to residues B23-B30 of insulin or an analogue thereof;
adding trypsin under conditions conducive to the enzymatic activity of trypsin such that trypsin catalyzes formation of a peptide bond between ArgB22 of the des-tripeptide [B1-B3]-des-octapeptide [B23-B30]-insulin intermediate product and the synthetic peptide to yield the des-[B1-B3]insulin analogue.
2. The method of claim 1 , wherein the folded single-chain or two-chain insulin-related precursor polypeptide is prepared by recombinant expression in a host cell.
3. The method of claim 2 , wherein the des-[B1-B3]insulin analogue has the amino acid sequence of SEQ ID NO: 5, 6, or 7.
4. The method of claim 1 , wherein the B23-B30 peptide segment has an amino acid sequence selected from SEQ ID NOS: 10-16.
5. The method of claim 1 , wherein the des-[B1-B3]insulin analogue further comprises a B29 substitution.
6. The method of claim 5 , wherein the substitution at B29 is selected from Glu B29 , Orn B29 , Diaminobutyric acid B29 , Diaminoproprionic acid B29 , Norleucine B29 , Aminobutric acid B29 , or Aminoprioprionic acid B29 .
7. The method of claim 1 , wherein the des-[B1-B3]insulin analogue further comprises a substitution at B24.
8. The method of claim 7 , wherein the substitution at B24 is selected from Cha B24 , penta-fluoro-Phe B24 , 2F-Phe B24 , 2-Cl-Phe B24 , 2-Br-Phe B24 , 4F-Phe B24 , 4-Cl-Phe B24 , or 4-Br-Phe B24 .
9. The method of claim 1 , wherein the des-[B1-B3]insulin analogue further comprises a substitution at B10.
10. The method of claim 9 , wherein the substitution at B10 is selected from a Asp B10 , Pro B10 , or Glu B10 substitution.