Physiologie und Biochemie der Streptomyceten VIII. Esteraseaktivität und Turimycin-Bildung in Kulturen vonStreptomyces hygroscopicus JA 6599

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Abstract
Esterase in cell-free extracts of Streptomyces hygroscopicus JA 6599 has a temperature-optimum of 35 degrees C, a pH-optimum with p-nitrophenylacetate as substrate at pH 7.7--8.1, with alpha-naphthylacetate at pH 7--9. Michaelis constants in cell-free extracts: with alpha-naphthylacetate Km = = 0.71 mM, with p-nitrophenylacetate Km = 0.21 mM. Phenylesters were better hydrolyzed than naphthylesters, phenylacetate was best hydrolyzed; beta-naphthylacetate was better hydrolyzed than alpha-naphthylacetate. Among the naphthylesters the ester of propionic acid was hydrolyzed best. Caprylate, stearate, and 0,0-diethyl-0-(p-nitrophenyl)-phosphate inhibit the splitting of alpha-naphthylacetate. A comparison with esterases of other biological origin shows that the enzyme studied can be a carboxylesterase (E.C.3.1.1.1.). In cultures of JA 6599 V13 and JA 6599-6 the change of esterase activity during the fermentation was determined. We found a carrelation between the enzymatic activity and the antibiotic-concentration in the culture medium.