Hydrolysis of ceramide trihexoside by a specific α-galactosidase from human liver

Author:

Ho Mae Wan1

Affiliation:

1. Department of Biochemistry, Queen Elizabeth College, University of London, Campden Hill, London W8 7AH, U.K.

Abstract

1. Partially purified ceramide trihexoside α-galactosidase from human liver was studied by using ceramide trihexoside specifically tritiated in the terminal galactose. 2. The hydrolysis of ceramide trihexoside was absolutely dependent on a mixture of sodium taurocholate and Triton X-100 and was markedly inhibited by human serum albumin and by NaCl. 3. The Lineweaver–Burk plot for ceramide trihexoside hydrolysis was upward curving. Ceramide lactoside inhibited hydrolysis of all concentrations of ceramide trihexoside. Ceramide digalactoside stimulated hydrolysis of low concentrations of ceramide trihexoside, but inhibited hydrolysis of high concentrations of the lipid. 4. α-Galactosidase activity assayed with the synthetic substrate 4-methylumbelliferyl α-d-galactopyranoside fractionated together with activity assayed with the natural substrate ceramide trihexoside. Both activities had identical heat-inactivation kinetics. 5. Characteristics of the hydrolysis of the synthetic substrate differed considerably from those of the natural substrate, including pH optimum, shape of the Lineweaver–Burk plot, and differential effects of inhibitors and activators. Mutual inhibition of hydrolysis between the synthetic and natural substrates was predominantly non-competitive. 6. These results are discussed in the light of special problems involved in the hydrolysis of lipids in an aqueous milieu.

Publisher

Portland Press Ltd.

Subject

Cell Biology,Molecular Biology,Biochemistry

Cited by 32 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

1. Glycolipid and Glycoprotein Degradation;Advances in Enzymology - and Related Areas of Molecular Biology;2006-11-22

2. Chapter 1a Normal and pathological catabolism of glycoproteins;New Comprehensive Biochemistry;1996

3. Galactosylgalactosylglucosylceramidase;Enzyme Handbook 4;1991

4. Kinetic studies on β-d-fucosidase of Littorina littorea L.;Comparative Biochemistry and Physiology Part B: Comparative Biochemistry;1985-01

5. Characterization and kinetics of β-d-gluco/fuco/galactosidase from sheep liver;Comparative Biochemistry and Physiology Part B: Comparative Biochemistry;1983-01

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