Untersuchungen zum Wirkungsmechanismus glykosidspaltender Enzyme, I. Darstellung und Eigenschaften spezifischer Inaktivatoren

Abstract

Three bromocyclohexanepentols and 3 dtbromocyclohexanetetrols were tested for their ability to specifically inactivate [beta]-glucosidases. With all enzyme preparations investigated (from Aspergillus oryzae, A. wentli, Saccharomyces cerevisieae. Helix pomatla and almond emulsin) DL-(1,2,4,6[beta],5)-6-bromocyclohexanepentol and DL-(1,2,4,6[beta],5)-4,6-dibromo-cyclohexanetetrol were effective deactivators; the deactivation of [beta]-glucosidase activity increased with time in 0.1[image] solution. Their reactivity is probably due to their previous dehydrobromination to the corresponding epoxide. Conduritol B epoxide [(3,5/4,6)-cyclohex-1-ene-tetrol oxide] causes a rapid deactivation of [beta] -glucosidases at a concentration of 0.001[image]. The strong inhibition of the deactivation reaction by the competitive inhibitors p-nitrophenyl-[beta]-D-thioglucopyranoside and D-gluconic acid-[delta]-lactone and the lack of activity of the otherwise more reactive ethylene oxide indicates that conduritol oxide reacts with the active centre of the enzymes. [beta]-galactosidase from H. pomatia and [beta]-xylosidase from A. oryzae are also deactivated by conduritol B epoxide.