API-2b, a New Alkaline Protease Inhibitor Produced by Streptomyces griseoincarnatus Strain No. KTo-250

Abstract

To obtain new alkaline protease inhibitors, further screening test was carried out. A strain (No. KTo-250), identified as Streptomyces griseoincarnatus was found to produce three kinds of inhibitors designated as API-2a, b and c in the order of mobilities from cathode terminal of the polyacrylamide gel.
First of all, API-2b was purified and this inhibitor differed from AP-I and S-SI in the mobility on polyacrylamide gel disc electrophoresis and pH stability and molecular weight.