[Subtilisin-like proteinase SSPB from Streptomyces spheroides, strain 35]

A serine proteinase possessing a fibrinolytic activity was isolated from a culture filtrate of Streptomyces spheroides, strain 35. A consecutive use of affinity chromatography on bacillichin-silochrome and bacitracin-sepharose and ion-exchange chromatography on anionie PAP and cationic KMT resulted in a homogeneous proteinase with 1060-fold purification and 19% yield. The enzyme has a molecular weight of 28000; its amino acid composition is Asp31, Ser28, Thr29, Glu9, Pro14, Gly35, Ala42, Val26, Ile14, Leu13, Met2, Tyr9, Phe4, Trp3, His6, Lys4, Arg10. The enzyme has a pI at pH greater than 10 and the activity optimum against Z-L-Ala-L-Ala-L-Leu-pNA at pH 10-11. The enzyme is stable within the pH range of 4-11 and in 6 M guanidinium chloride pH 8.0 in the presence of Ca2+. The enzyme is inhibited by diisopropylfluorophosphate and benzylsulfofluoride, specific inhibitors of serine proteinases as well as by potato proteinase inhibitor. The serine proteinase SSPB isolated from Str. spheroides, strain 35 can be related to subtilisin-like serine proteinase, especially to those of SGPD and SGPE of Str. griseus.