[Extracellular serine proteinase A of Streptomyces rutgersensis]

Extracellular serine proteinase of Streptomyces rutgersensis (proteinase A) has been isolated by affinity chromatography on bacitracin-Sepharose in the presence of Na2EDTA. The proteolytic activity of the enzyme is completely suppressed by specific inhibitors of serine proteinases, phenylmethylsulfonylfluoride and diisopropylfluorophosphate, but is insensitive to Na2EDTA and sodium p-hydroxymercuribenzoate. The enzyme activity towards hemoglobin is maximal at pH 9-10, the maximal stability is observed within the pH range of 6-10. The molecular mass as determined by SDS-pore gradient electrophoresis is equal to 20000 +/- 2000. Proteinase A is similar to the proteinases A and B of Streptomyces griseus in terms of i) amino acid composition--Asp17Thr22Ser23Clu7Pro6. X Gly30Ala13Cys4Val18Met1Ile5Leu9Tyr10Phe6Trp1His2Arg7, ii) amino terminal sequence--Leu-Ser-Gly-Gly-Asp-Ala-Ile-Tyr-Ser-Asn-Ser-Ser-Xaa-Xaa-Ser-Leu-, iii) specificity of insulin B-chain hydrolysis, and iiii) ability to exhibit proteolytic activity in 8 M urea or 6 M guanidinium chloride. The enzyme lyzes the cells of Candida utilis. Besides proteinase A, S. rutgersensis produces at least two other proteolytic enzymes.