Comparative characterization of two serine endopeptidases from Nocardiopsis sp. NCIM 5124

A protease-producing, crude oil degrading marine isolate was identified as Nocardiopsis sp. on the basis of the morphology, cell wall composition, mycolic acid analysis and DNA base composition. The Nocardiopsis produces two extracellular proteases, both of which are alkaline serine endopeptidases. Protease I was purified to homogeneity by chromatography on CM-Sephadex at pH 5.0 and pH 9.0. Protease II was purified using DEAE-cellulose, Sephadex G-50, phenyl-Sepharose and hydroxyapatite chromatography. Protease I and II had almost similar M(r) of 21 kDa (Protease I) and 23 kDa (Protease II), pI of 8.3 and 7.0 respectively with pH and temperature optima for activity between 10.0 and 11.0 and about 60 degrees C. Specific activities were 152 and 14 U/mg respectively on casein. However, Protease I was antigenically unrelated to Protease II. Both proteases were endopeptidases and required extended substrate binding for catalysis. Both proteases had collagenolytic and fibrinolytic activity but only Protease I had elastinolytic activity. The proteases were chymotrypsin-like with respect to their amino acid compositions and N-terminal sequences.