The Initial Attack Sites of a Streptomyces Alkalophilic Proteinase on Oxidized Insulin B-Chain

Abstract

The sites on oxidized insulin B-chain substrate initially attacked by an alkalophilic proteinase from a Streptomyces sp., were investigated under incubation conditions employing one part enzyme to one thousand parts of substrate at 0°C.
Analysis of the peptides produced after 10 to 40 seconds of incubation revealed that the enzyme, which has an optimum pH of around 13, first attacks two peptide linkages “-Leu (15)-_??_Tyr (16)-_??_Leu (17)-” of the oxidized insulin B-chain with equal efficiency.