Section 6
Chapter 5,245

Effect of hydrogenation of glucosyl ceramide and galactosyl ceramide on their enzymatic hydrolysis

Vaccaro, A.M.; Muscillo, M.; Suzuki, K.

Clinica Chimica Acta 131(1-2): 1-14


ISSN/ISBN: 0009-8981
Accession: 005244936

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The earlier observation that N-stearoyl- and N-lignoceroyl-glucosyl-dihydrosphingosines have much lower affinity to the hydrolytic enzyme, glucosylceramidase [human fibroblasts, EC], than the natural mixture of glycosylceramide was further pursued with catalytically hydrogenated natural substrate. Similar experiments were also carried out for hydrolysis of galactosylceramide of different structures by galactosylceramidase [EC]. The hydrogenation procedure completely saturated both fatty acid and long chain base moieties. For either enzyme, the hydrogenated natural substrate had affinity approximately half of the untreated natural substrate mixture. However, the synthetic glucosylcermides which contained a single saturated fatty acid and dihydrosphingosine had generally still lower affinity than the hydrogenated natural mixture. When 2 synthetic substrates of different fatty acids were mixed together, the affinity to the enzyme increased to a level much higher than that of either of the synthetic substrates alone and reached that of the hydrogenated natural substrate mixture. The findings were similar for galactosylceramide hydrolysis except that the synthetic substrate with palmitic of stearic acid had affinity to the enzyme not much lower than that of the hydrogenated natural substrate mixture. These effects of different structures on their enzymatic hydrolysis remained similar when other constituents of the assay mixture, such as the buffer and detergents, were varied.

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