PREPARATION AND CRYSTALLIZATION OF DES (B-CHAIN C-TERMINAL) HEPTAPEPTIDE INSULIN

An insulin analogue, des（B-chain C-terminal） heptapeptide insulin （DHPI）, has been prepared from des（B-chain C-terminal） pentapeptide insulin （DPI） by the limited hydrolysis with carboxypeptidase A at pH 7.4, 0℃, for 10hr. The desired product, collected from the hydrolysate through Sephadex G-50 column chromatography, has been identified by chemical analysis of the C-terminal amino acid, C-terminal sequence and amino acid composition, and polyacrylamide gel plate electrophoresis. DHPI can crystallize in the form of platelets in a 0.05M citrate buffer, pH 5.9-6.1 containing 33% acetone and a trace of ZnAc. Pure DHPI is inactive by the mouse convulsion test.