A simple, economical method of converting gene expression products of insulin into recombinant insulin and its application *

Abstract

A method, by which the gene expression product of recombinant single chain insulin can be converted into insulin by directly digesting with trypsin, has been established. This method has been used in process of porcine insulin precursor (PIP), [B16A1a] PIP and [B26Ala]PIP into (desB30) insulin, (desB30)[B16Ala] insulin and (desB30)[B26Ala] insulin, respectively, and all of them retain full biological activity of that of their corresponding parent, recombinant human insulin, [B16Ala] insulin and [B26Ala] insulin. The results further demonstrate that the C-terminal residue of B chain is not necessary for insulin's biological activity. Compared with the method of transpeptidation, this method is simple, with a high yield, and avoids the use of organic reagents, and in comparison with the trypsin/carboxypeptidase method, it omits the use of carboxylpeptidase. Besides, (desB30) [B16Ala] insulin and (desB30) [B26Ala] insulin still remained without self-association property as that of their parents, which demonstrate that they are monomeric insulin. So they can be used for substituting for monomeric insulin, [B16Ala] insulin and [B26Ala] insulin, in clinical applications.