Investigation of the Metabolism of [3H]GA20-13-O-glucoside Vicia faba L. in vivo and in vitro

Abstract

Summary [ 3 H]GA 20 -13-O-glucoside fed to epicotyls, immature fruits and leaves of Vicia faba was found to be hydrolysed to a small extent giving [ 3 H]GA 20 , which thereafter in epicotyls and fruits was preferentially transformed to [ 3 H]GA 29 by 2β-hydroxylation. These results of the in vivo experiments correspond with those of in vitro investigations of the β-glucosidases from epicotyls. The s-glucosidases separated on CM-Sephadex C-50 showed substantially lower hydrolytic activity toward [ 3 H]GA 20 -13-O-glucoside than toward other substrates, e.g. [ 3 H]GA 8 -2-O-glucoside and p-nitrophenyl-β-D-glucoside. The observed low hydrolysis rate of [ 3 H]GA 20 -13-O-glucoside in vitro and in vivo can be only explained by the absence in these tissues of β-glucosidases specific for GA 20 -13-O-glucoside. For the liberation of the low amount of [ 3 H]GA 20 from the glucoside the detected β-glucosidases with unknown specificity should be responsible.