[Chymotrypsin-like proteinases in microbial proteolytic complexes]

A considerable amount of proteinase of chemotrypsin type (AO-ct) was found in the proteolytic system of Asp. oryzae, strain "h"-476. The proteinase produces an intensive effect when hydrolyzing p-nitrophenyl acetate (p-NPA) -- 18-20 times as strong as that of crystalline chemotrypsin. Comparison of the AO-ct and chemotrypsin properties resulted in proving the enzyme nature of the p-NPA hydrolysis reaction. A study of AO-ct specificity with the presence of such substrates as p-NPA, o-nitro-phenyl acetate, 2,4,dinitrophenyl acetate (2,4-DNP) showed that displacement of the nitrogroup into the ortho-position produces a 4-fold inhibition in the hydrolysis, introduction into the molecule of other nitrogroup (2,4-DNP) -- a 9-10 fold inhibition, the effect of chemotrypsin on them is considerably weaker, but 2.4-DNP hydrolyses more intensively. Definite differences are found in the effect of AO-ct and chemotrypsin in hydrolysis of phenyl acetate, N-benzoyl-tyrosine-methyl ester and casein. All the reactions are completely inhibited with DFP. The esterolytic activity (substrate p-NPA) is detected in a series of the exocellular proteolytic complexes, their effect being rather intensive but diverse.