Structural studies on des-pentapeptide (B26-30)-insulin. I. The preparation and properties of des-pentapeptide-insulin.

It has been suggested in our previous reports that the B-chain C-terminal peptide sequence of the insulin molecule plays an important role in the primary biological activity of this hormone. It is interesting, therefore, to study the structure-function relationship of a series of related insulin analogues. An improved method has been used in this paper for the preparation of des-pentapeptide (B26-30)-insulin (DPI) suitable for the growth of single crystals. These crystals possess 88% of the receptor binding activity of insulin and exhibit hormonal activity of 20 I.U. per milligramme in the mouse convulsion test. In the presence of zinc ions, DPI cross-reacts immunologically with insulin antibody.