Characterization of the activation of rat liver beta-glucosidase by sialosylgangliotetraosylceramide.

摘要: We show that sialosylgangliotetraosylceramide (GM1) is a potent activator of delipidated (sodium cholate- and 1-butanol-extracted) lysosomal rat liver glucocerebroside:beta-glucosidase. Stimulation 4-methylumbelliferyl-beta-D-glucopyranoside hydrolysis by the beta-glucosidase was markedly dependent upon concentration GM1 in assay medium. Estimations critical micellar (CMC) performed fluorometrically using dye N-phenylnaphthylamine revealed two CMC values above 18 degrees C; primary micelles (3.32 microM) temperature-independent whereas secondary decreased with decreasing temperature (17.2 10.8 microM at 37 20 C, respectively). In range 18-39 activity increased sharply when micelles. Although heat-stable factor, purified from spleen patient Gaucher's disease, had profound effect on activation GM1, it only slightly (14.8 versus 17.2 C). The factor (8 micrograms/ml) changed shape curve sigmoidal to hyperbolic, suggesting permits be activated or monomers. results gel filtration chromatography sucrose gradient centrifugation H2O D2O associated an increase size enzyme 45,800 178,500 daltons partial specific volume 0.697 0.740 ml/g. active, reconstituted appears consist 50% protein ganglioside (56 molecules/178,500 g). Concentrations below rate inactivation irreversible inhibitor conduritol B epoxide indicating monomers do interact enzyme, even though they not enzyme.