PURIFICATION AND CHARACTERIZATION OF A NOVEL PROTEASE FROM CULTURE FILTRATES OF A STREPTOMYCES SP

A fibrinolytic protease has been isolated from Streptomyces sp, cultur e filtrate by successive chromatography on Mono S and Sephadex G50. Th e purified protease had a molecular mass of 33 kDa and had an isoelect ric point of 6.7. It showed a sharp pH optimum at 7.8 with maximal pro tease activity between 35 degrees C and 50 degrees C. Its amino acid c omposition and aminoterminal sequence (17 residues) were determined. T he protein exibited marked hydrolytic activity toward the substrates N -Succ-(Ala)(2)-Pro-Phe-pNA (K-m = 0.77 mM, V-max = 24.2 mu mol mg(-1) min(-1)) and N-Succ-(Ala)(2)-Pro-Leu-pNA (K-m = 0.92 mM, V-max = 7.7 m u mol mg(-1) min(-1)). It was totally inhibited by alpha 1-antitrypsin , D-Phe-Pro-Arg-chloromethylketone and sodium dodecyl sulfate but was insensitive to EDTA, dithiothreitol, phenylmethylsulfonyl fluoride, so ybean trypsin inhibitor, pepstatin or elastatinal. In this respect, th is protease differed in its physico-chemical and biochemical propertie s from other extracellular proteases previously found in bacteria and fungi. The results suggest that it has properties of chymotrypsin-like serine-type proteases.