Further characterization of rat dihydroceramide desaturase: tissue distribution, subcellular localization, and substrate specificity
| Autor: | Catherine Causeret, Paul P. Van Veldhoven, Gerd Van der Hoeven, Luc Geeraert, Guy P. Mannaerts |
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| Rok vydání: | 2000 |
| Předmět: |
Male
Ceramide Detergents Biology Ceramides Endoplasmic Reticulum Biochemistry Substrate Specificity chemistry.chemical_compound Albumins Centrifugation Density Gradient Animals Tissue Distribution Rats Wistar Sphingosine Harderian Gland Endoplasmic reticulum Organic Chemistry Cell Biology Dihydroceramide desaturase Subcellular localization Enzyme assay Rats chemistry Liver Models Chemical Microsome biology.protein Microsomes Liver Cell fractionation Oxidoreductases NADP Subcellular Fractions |
| Zdroj: | Lipids. 35(10) |
| ISSN: | 0024-4201 |
| Popis: | The introduction of the double bond in the sphingoid backbone of sphingolipids occurs at the level of dihydroceramide via an NADPH-dependent desaturase, as discovered in permeabilized rat hepatocytes. In the rat, the enzyme activity, which has now been further characterized, appeared to be mostly enriched in liver and Harderian gland. By means of subcellular fractionation of rat liver homogenates and density gradient separation of microsomal fractions, the desaturase was localized to the endoplasmic reticulum. Various detergents were inhibitory to the enzyme, and maximal activities were obtained in the presence of NADPH and when the substrate was complexed to albumin. In the presence of albumin, the chain length of the fatty acid of the truncated dihydroceramides hardly affected the activity. Finally, in view of a likely evolutionary relationship between desaturases and hydroxylases, the formation of hydroxylated intermediates was analyzed. No evidence for their presence was found under our assay conditions. |
| Databáze: | OpenAIRE |
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