Characterization of a nonspecific activator protein for the enzymatic hydrolysis of glycolipids.
We have studied the substrate specificities of a non-specific activator protein on the enzymatic hydrolyses of the following compounds: GM1 and GM2, as well as several of their derivatives including oligosaccharides, GgOse3Cer-II3-sulfate and LacCer-II3-sulfate, Gb-Ose3Cer and GbOse4Cer, three neolacto-series glycosphingolipids, and two non-ceramide glycolipids. Our results show that this activator protein has a broad spectrum of activity and exhibits the properties of a nonspecific natural detergent. The evidence of non-specificity was the ability of this activator protein to stimulate the hydrolyses of glycolipids, regardless of glycosphingolipids or non-ceramide glycolipids, carried out by glycosidases from animals, plants, and microorganisms. Its activity was, however, limited to substrates that had a lipid moiety. The oligosaccharide of GM1 and deacetyl-fatty acid free GM1 (II3-NeuGg-Ose4-sphingosine) were hydrolyzed by beta-galactosidase in the absence of this activator protein.
Li
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Department of Biochemistry, Tulane University School of Medicine, New Orleans, Louisiana 70112.
Sonnino
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Tettamanti
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D004789:Enzyme Activation; D005732:Gangliosides / Q000378:metabolism; D006017:Glycolipids / Q000378:metabolism*; D006026:Glycoside Hydrolases / Q000378:metabolism*; D006028:Glycosphingolipids / Q000378:metabolism; D006801:Humans; D006868:Hydrolysis; D011506:Proteins / Q000302:isolation & purification / Q000502:physiology*; D013379:Substrate Specificity
D005732:Gangliosides; D006017:Glycolipids; D006028:Glycosphingolipids; D011506:Proteins; D006026:Glycoside Hydrolases