Purification and characterization of a broad specificity beta-glucosidase from sheep liver.
1. A soluble beta-glucosidase from sheep liver has been isolated and purified 114-fold by conventional enzyme fractionation procedures. The specific activity of the purified enzyme was 5910 mU/mg of protein. 2. The enzyme has a broad specificity and hydrolyzes the p-nitrophenyl derivatives of beta-D-glucose, beta-D-galactose, beta-D-fucose, beta-D-xylose and alpha-L-arabinose. The best Vmax/Km value corresponds to the beta-glucosidase activity. 3. The enzyme has a pH optimum between 4.5-5.5 for all the activities, and mol. wt 95,000. 4. A variety of chemicals was tested as possible activators or inhibitors. 5. The enzyme is strongly inhibited by aldono 1-5 lactones and DMDP. 6. The kinetic evidences suggest a substrate activation model and the existence of two active sites (a "gluco-fuco" site and a "galacto" site). 7. The activation energies were calculated from beta-glucosidase and beta-galactosidase activities.
Chinchetru
M A
MA
Departmento de Bioquímica y Biología Molecular, Universidad de León, España.
Cabezas
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Calvo
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D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D005959:Glucosidases / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D050113:Imino Furanoses; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D008353:Mannitol / Q000031:analogs & derivatives; D008970:Molecular Weight; D011759:Pyrrolidines; D012756:Sheep; D013379:Substrate Specificity; D013816:Thermodynamics; D001616:beta-Galactosidase / Q000032:analysis; D001617:beta-Glucosidase / Q000032:analysis / Q000037:antagonists & inhibitors / Q000302:isolation & purification*
D000470:Alkaloids; D050113:Imino Furanoses; D011759:Pyrrolidines; D008353:Mannitol; C043121:2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine; D005959:Glucosidases; D001617:beta-Glucosidase; D001616:beta-Galactosidase