Exolytic hydrolysis of toxic plant glucosides by guinea pig liver cytosolic beta-glucosidase

• Published in: The Journal of biological chemistry 1992-07, Vol.267 (20), p.14027-14032
• Main Authors: Gopalan, V. (University of New Mexico, Albuquerque, NM), Pastuszyn, A, Galey, W.R. Jr, Glew, R.H
• Format: Article
• Language: English
• Subjects: AMIGDALINA; amygdalin; Amygdalin - metabolism; AMYGDALINE; Analytical, structural and metabolic biochemistry; Animals; beta -glucosidase; beta-Glucosidase - metabolism; Biological and medical sciences; Carbohydrate Sequence; Chromatography, High Pressure Liquid; CITOPLASMA; COBAYA; COBAYE; COMPOSE PHENOLIQUE; COMPUESTOS FENOLICOS; CYTOPLASME; Cytosol - enzymology; Disaccharides - metabolism; enzymatic activity; Enzymes and enzyme inhibitors; Fundamental and applied biological sciences. Psychology; GLICOSIDOS; GLUCOSIDASA; GLUCOSIDASE; glucosides; Glucosides - metabolism; GLYCOSIDE; Guinea Pigs; HIDROLISIS; Hydrolases; HYDROLYSE; hydrolysis; Kinetics; liver; Liver - enzymology; Molecular Sequence Data; Plants, Toxic; Substrate Specificity; TOXICIDAD; TOXICITE; transport
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(19)49673-7

We demonstrate that although the guinea pig liver cytosolic beta-glucosidase does not catalyze the hydrolysis of gentiobiose, it does hydrolyze, disaccharide-containing glycosides such as p-nitrophenyl-, beta-D-gentiobioside (Glc beta1 leads to 6 Glcbeta-pNP) and mandelonitrile-beta-D-gentiobioside (amygdalin). Furthermore, we establish that the enzyme attacks disaccharide glycosides exolytically; specifically, we document the exolytic deglucosylation of amygdalin and the generation of the intermediate monosaccharide glycoside mandelonitrile-beta-D-glucoside prior to the formation of the aglycone (mandelonitrile). We also show that the cytosolic beta-glucosidase catalyzes the hydrolysis of various phenolic (e.g. arbutin and salicin) and cyanogenic plant glucosides (e.g. prunasin). Using the everted gut-sack technique, we demonstrate that the plant glucosides, amygdalin, prunasin, and vicine, are transported across the small intestine of the guinea pig efficiently and without being hydrolyzed. Based on thess data we speculate that the cytosolic beta-glucosidase may participate in biotransformation of toxic plant glucosides