Ceramide synthesis in rat brain: characterization of the synthesis requiring pyridine nucleotide.
Ceramide synthesis in rat brain: characterization of the synthesis requiring pyridine nucleotide.
复制标题
大鼠脑中的神经酰胺合成：需要吡啶核苷酸的合成的表征。
DOI：
10.1016/0003-9861(80)90409-9
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发表时间：
1980
影响因子：
3.9
通讯作者：
Y. Kishimoto
中科院分区：
文献类型：
--
作者：
I. Singh;Y. Kishimoto
The unusual ceramide synthesis reaction, requiring pyridine nucleotide, in a rat brain preparation (I. Singh and Y. Koshimoto, 1978) Biochem. Biophys. Res. Commun. 82, 1287–1293) has been further characterized. The enzyme, found in brain particulate fraction, requires heat-stable and heat-labile factors which are also required for fatty acid α-hydroxylation in brain. The pH optimum is 7.0, and the apparent K m value for lignoceric acid is 12 μ m. The activity was stimulated by 50 m m KCl and 1 m m Mg 2+ but inhibited by Ca 2+, Mn 2+ and strongly inhibited by 1 m m EDTA. Sphingosine at the optimum concentration of 40 μ m stimulated the activity more than threefold. The ceramide synthesis was strongly inhibited by N-ethylmaleimide. In agreement with previous results which suggested the possible involvement of an electron-transfer chain, the synthesis of ceramide under a nitrogen atmosphere was only 1 10 th of the control. CoASH inhibited the reaction, but ATP had no apparent effect. In the presence of 0.5 m m ATP a low concentration of CoASH slightly stimulated the synthesis. The enzyme appears to be present only in brain; rat liver, kidney, and spleen have no similar activity. While the enzyme actively synthesizes ceramide from lignoceric acid, it is not significantly active for palmitic acid. On subcellular fractionation, the crude mitochondrial fraction was the most active although much activity was lost during centrifugation because of inhibition by sucrose. These properties indicate that this reaction is different from the two previously reported ceramide syntheses, one from fatty acyl CoA and sphingosine and the other by the reverse reaction of ceramidase.
