Isolation of Streptomyces sp. producing glucose-tolerant .BETA.-glucosidases and properties of the enzymes.

Abstract

Streptomyces sp. No. 35, taxonomically closed to S. thermodiastaticm, was isolated from domestic soil. It showed δ-glucosidase activity only in the cells. The enzyme synthesis was induced by cellobiose. Repeated DEAE-Toyopearl chromatography of a sonic extract of the cells showed three activity peaks, F1, F2, and F3, which were eluted in the relative amount of 50:50:1 in this order by an NaCl concentration gradient. The enzymes were purified to homogeneity. Molecular weights of F1, F2, and F3 were 100, 000, 105, 000, and 130, 000 by gel filtration, and 52, 000, 50, 000, and 52, 000, respectively, by sodium dodecyl sulfate-polyacrylamide-gel electrophesis. F1 and F2 hydrolyzed PNP-δ-glucoside and cellobiose nearly at the same rate, while F3 hydrolyzed the former slightly. F1 and F2 were inhibited by glucose, giving Kis of 56 and 40 mM, respectively. On the other hand, F3 was activated twofold by 0.1 M glucose and inhibited 50% by 1 M glucose. Xylose also similarly activated F3. All the enzymes had δ-galactosidase activities. The δ-galactosidase activity of F3 was not activated by any compounds tested, but rather inhibited by glucose and D-arabinose.