Yamashita H, Nakamura A, Noguchi N, Niki E, Kühn H
Research Center for Advanced Science and Technology, University of Tokyo, Meguro, Japan.
FEBS Lett. 1999 Feb 26;445(2-3):287-90. doi: 10.1016/s0014-5793(99)00137-4.
It is generally accepted that the oxidation of pentadiene structures of polyunsaturated lipids by lipoxygenase (LOX) is regio- and enantio-specific, while the free radical-mediated lipid peroxidation gives stereo-random racemic products. It was confirmed that the oxidation of human low density lipoprotein (LDL) by 15-LOX from rabbit reticulocytes gave phosphatidylcholine (PC) and cholesteryl ester (CE) hydroperoxides regio-, stereo- and enantio-specifically. 15-LOX also oxidized human plasma to give specific PC and CE hydroperoxides in spite of the presence of high concentrations of antioxidants. More CE hydroperoxides were formed than PC hydroperoxides from LDL, but the reverse order was observed for plasma oxidation. The S/R ratio of the hydroperoxides decreased during long time incubation but remained significantly larger than one, while free radical-mediated oxidation of LDL and plasma gave racemic products.
普遍认为，脂氧合酶（LOX）对多不饱和脂质的戊二烯结构进行氧化具有区域和对映体特异性，而自由基介导的脂质过氧化反应则产生立体随机的外消旋产物。已证实，兔网织红细胞中的15-脂氧合酶对人低密度脂蛋白（LDL）进行氧化时，会区域、立体和对映体特异性地生成磷脂酰胆碱（PC）和胆固醇酯（CE）氢过氧化物。尽管存在高浓度的抗氧化剂，15-脂氧合酶仍会氧化人血浆，生成特定的PC和CE氢过氧化物。LDL生成的CE氢过氧化物比PC氢过氧化物更多，但血浆氧化时情况则相反。长时间孵育期间，氢过氧化物的S/R比值下降，但仍显著大于1，而自由基介导的LDL和血浆氧化则产生外消旋产物。
