Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.21 (beta-glucosidase)
 3,280 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Initial rates of transglucosylation with diglucosides and diglucose-azoxyglycosides as acceptor by cycad beta-glucosidase were tentatively obtained. The formation of beta-1,3 glucosidic linkage was predominant, except for neocycasin A (beta-laminaribioside of methylazoxymethanol, MAM) as an acceptor. With neocycasin A as an acceptor, beta-1,4 and beta-1,6 glucosidic linkages were formed but beta-1,3 linkage was not. Whereas with laminaribiose as acceptor, laminaritriose and triose with beta-1,6 linkage were formed, but triose with beta-1,4 linkage was not. On the other hand, with other diglucoses and neocycasin B (beta-gentiobioside of MAM) as acceptor, all the linkages formed were beta-1,3 glucosidic. The aglycone of azoxyglycosides, MAM, affected the kind of linkages formed in the trisaccharides. When initial rates of the linkage formation of the transglucosylation at 100 mM acceptor were compared with the hydrolysis rates obtained by Lineweaver-Burk plot, the order of formation rates of the di- and tri-glucosides by transglucosylation was the same as obtained for the hydrolysis parameter, kcat/Km. Km values for various substrates could be grouped according to the kind of the linkages (beta-1,3, beta-1,4, and beta-1,6) first split by the enzyme.
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PMID:Substrate specificity and transglucosylation catalyzed by cycad beta-glucosidase. 862 14

The glucoside cycasin, an effective hepatotoxin and carcinogen in conventional rats, fails to produce these effects when administered to germfree rats. The hepatotoxic and carcinogenic effects of cycasin can also be elicited after prior hydrolysis to the aglycone. The aglycone (MAM) and the synthetic aglycone acetate ester produce all the effects in germfree rats of which the intact glucoside is capable only when fed to conventional rats. The aglycone is therefore the proximate carcinogen. Its liberation from the glucoside in conventional rats is mediated in the intestinal tract by a beta-glucosidase of bacterial origin. Intraperitoneal administration of the synthetic aglycone acetate and the free aglycone appears to be the most effective route for tumor induction and, of these resulting tumors, the most frequent are in the intestinal tract.
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PMID:Tumor induction in germfree rats with methylazoxymethanol (MAM) and synthetic MAM acetate. 1862 50