Ja. Perezpons et al., PROPERTIES OF A NOVEL GLUCOSE-ENHANCED BETA-GLUCOSIDASE PURIFIED FROMSTREPTOMYCES SP (ATCC-11238), Biochimica et biophysica acta. Protein structure and molecular enzymology, 1251(2), 1995, pp. 145-153
An inducible intracellular beta-glucosidase (EC 3.2.1.21) from Strepto
myces sp. QM-B814 (ATCC 11238) has been purified and characterized, Th
e purified polypeptide is monomeric with a relative molecular mass of
62 kDa by SDS-PACE and 42 kDa by size-exclusion chromatography; its is
oelectric point is 4.2, The difference in the molecular mass values ca
n be attributed to the glycosylated nature of the protein. The purifie
d enzyme has a pH optimum of 6.0-6.5. The temperature optimum for acti
vity is 50 degrees C; at this temperature the enzyme is stable for 1 h
. The enzyme hydrolyzes mainly aryl-beta-glucosides but also presents
significant activity against beta-linked disaccharides and maltose. Th
e enzyme displays an unusual kinetic behavior and biphasic Lineweaver-
Burk and Eadie-Hofstee plots for p-nitrophenyl-beta-D-glucoside and ce
llobiose were obtained. The enzyme presents beta-glycosyltransferase a
ctivity and an exoglycosidase-type action on cellodextrins. It is inhi
bited by delta-gluconolactone(K-i 0.44 mM) but, remarkably, glucose in
the range 25-200 mM enhances the rate of p-nitrophenyl-beta-D-glucosi
de hydrolysis.