Facile synthesis of human insulin by modification of porcine insulin

Abstract

Abstract A method of converting natural porcine insulin to human insulin by reversibly blocking the six carboxyl groups in porcine insulin, digesting the blocked porcine insulin with trypsin to remove the carboxyl terminal octapeptide from the porcine insulin B chain and generating a free carboxyl group in the arginine residue in position 22 of the B chain, and then reversibly blocking all amino groups preferably with BOC azide and coupling the free carboxyl at position 22 to a synthetic octapeptide which corresponds to the sequence at the carboxyl end of the B chain in human insulin, and finally removing all protecting groups from carboxyl and amino and purifying and recovering synthetic human insulin. This method is also susceptible to preparing radioactively labelled human insulin by utilizing radioactive amino acids in the synthesis of the octapeptide grafted or placed on the porcine residue. Further the present method also permits the facile synthesis of insulin analogs, since any selected amino acid sequence may be attached to the carboxyl group at position 22. The above method, in summary, by means of chemical and enzymatic treatment, makes possible the removal quantitatively and selectively of the carboxyl terminal octapeptide from the porcine insulin B chain. This fragment may be replaced by an analogous synthetic human octapeptide to give a protein which is identical to human insulin by a satisfying number of criteria.

Inventors

• 👤 Michael A Ruttenberg

Bibliographic Details