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B6db references: 84126811

type Journal Article
authors Williams, R. D.; Wang, E.; Merrill, A. H., Jr.
title Enzymology of long-chain base synthesis by liver: characterization of serine palmitoyltransferase in rat liver microsomes
journal Arch Biochem Biophys
sel unselected
ui 84126811
year (1984)
volume 228
number 1
pages 282-91.
keywords Acyl Coenzyme A/metabolism
abstract Serine palmitoyltransferase [palmitoyl-CoA:L-serine C- palmitoyltransferase (decarboxylating) EC] catalyzes the initial and committed step in the biosynthesis of the long-chain bases of sphingolipids. A simple assay, based upon the incorporation of [3H]serine into the chloroform-soluble product 3-ketosphinganine, has been developed and demonstrated to be valid for analyzing this enzyme in rat liver microsomes. More than 75% of the serine palmitoyltransferase of rat liver was associated with the microsomal subfraction. The dependencies of activity on the incubation time, pH, temperature, other assay components (e.g., dithiothreitol, EDTA, and pyridoxal 5'-phosphate), and the concentrations of microsomal protein, L-serine, and palmitoyl-CoA were investigated. The requirement of pyridoxal 5'-phosphate for activity was established by formation of the apoenzyme by dialysis against cysteine, and recovery of full activity upon reconstitution with the coenzyme. Activities with fatty acyl-CoA's of varying alkyl chain length were distributed nearly symmetrically around a maximum at 16 carbons (palmitoyl-CoA) for the fully saturated substrates. Less activity was obtained with the CoA thioesters of cis- unsaturated fatty acids, but trans-9-hexadecenoyl-CoA yielded essentially the same activity as palmitoyl-CoA. Hence, this enzyme is capable of initiating the synthesis of the major long-chain bases, as well as compounds that may constitute the unidentified bases reported in analyses of mammalian sphingolipids.
last changed 2004/09/14 13:36

B6db references