Guzmán M, Klein W, Gómez del Pulgar T, Geelen M J
Department of Biochemistry and Molecular Biology I, School of Biology, Complutense University, Madrid, Spain.
Lipids. 1999 Apr;34(4):381-6. doi: 10.1007/s11745-999-0376-6.
The present work was undertaken to study the metabolism of fatty acids with trans double bonds by rat hepatocytes. In liver mitochondria, elaidoyl-CoA was a poorer substrate for carnitine palmitoyltransferase I (CPT-I) than oleoyl-CoA. Likewise, incubation of hepatocytes with oleic acid produced a more pronounced stimulation of CPT-I than incubation with trans fatty acids. This was not due to a differential effect of cis and trans fatty acids on acetyl-CoA carboxylase (ACC) activity and malonyl-CoA levels. Elaidic acid was metabolized by hepatocytes at a higher rate than oleic acid. Surprisingly, compared to oleic acid, elaidic acid was a better substrate for mitochondrial and, especially, peroxisomal oxidation, but a poorer substrate for cellular and very low density lipoprotein triacylglycerol synthesis. Results thus show that trans fatty acids are preferentially oxidized by hepatic peroxisomes, and that the ACC/malonyl-CoA/CPT-I system for coordinate control of fatty acid metabolism is not responsible for the distinct hepatic utilization of cis and trans fatty acids.
本研究旨在探讨大鼠肝细胞对具有反式双键的脂肪酸的代谢情况。在肝脏线粒体中，反油酸辅酶A（elaidoyl-CoA）作为肉碱棕榈酰转移酶I（CPT-I）的底物，其反应活性低于油酸辅酶A（oleoyl-CoA）。同样，用油酸孵育肝细胞比用反式脂肪酸孵育对CPT-I的刺激作用更明显。这并非是由于顺式和反式脂肪酸对乙酰辅酶A羧化酶（ACC）活性和丙二酰辅酶A水平的差异效应所致。反油酸在肝细胞中的代谢速率高于油酸。令人惊讶的是，与油酸相比，反油酸是线粒体尤其是过氧化物酶体氧化的更好底物，但却是细胞和极低密度脂蛋白三酰甘油合成的较差底物。因此，结果表明反式脂肪酸优先被肝脏过氧化物酶体氧化，并且脂肪酸代谢协调控制的ACC/丙二酰辅酶A/CPT-I系统并非导致顺式和反式脂肪酸在肝脏中不同利用情况的原因。
