B-chain shortening of matrix-bound insulin with pepsin, II. Preparation and properties of camel des-pentapeptide (B26-30)- and des-PheB1-des-pentapeptide (B26-30)- insulin.

ABSTRACT

Digestion of matrix-bound camel insulin with pepsin was found to be restricted to the cleavage of the peptide bond between phenylalanine(B25) and tyrosine(B26). Purification of the camel des-pentapeptide(B26-30)-insulin obtained was achieved by gel filtration and ion exchange chromatography, yielding a molecularly uniform product. In the same way, camel des-PheB1-insulin prepared according to a method described for bovine insulin was hydrolyzed with pepsin and purified to give the des-PheB1-despentapeptide(B26-30)-insulin. The biological activity of these modified camel insulins was found to be as much reduced as the corresponding bovine insulin analogues. However, the reduced biological activity of camel des-PheB1-insulin (60%) was a contrast to the fully active bovine des-PheB1-insulin.