Mitchell D Y, Petersen D R
Hepatobiliary Research Center, University of Colorado Health Sciences Center, Denver 80220.
Arch Biochem Biophys. 1989 Feb 15;269(1):11-7. doi: 10.1016/0003-9861(89)90081-7.
Lipid peroxidation in microsomal membranes produces a large number of aldehydes, alcohols, and ketones, some of which have been shown to be cytotoxic. This study has determined the kinetic parameters for the oxidation of aldehyde lipid peroxidation products by purified rat hepatic microsomal aldehyde dehydrogenase (ALDH). Livers were obtained from male Sprague-Dawley rats for preparation of microsomal ALDH which was purified 400-fold. Kinetic parameters, Vmax and V/K, were determined for saturated and unsaturated aldehydes of three to nine carbons in length in the presence of NAD+. Of the aldehydes examined, only acrolein and 4-hydroxynonenal were not oxidized by ALDH. The Vmax values (mumol NADH produced/min/mg protein) increased linearly with carbon chain length and ranged from 6.5 to 23 for the saturated series and 4.0 to 9.0 for the unsaturated aldehydes. The affinity constant V/K (nmol NADH produced/min/mg protein/nmol aldehyde/liter) also increased with carbon chain length and ranged from 12 to 9000 for the saturated aldehydes and 13 to 5300 for the unsaturated aldehydes. These results suggest that microsomal ALDH may serve a biological role for detoxification of reactive aldehydes produced by lipid peroxidation of microsomal membranes.
微粒体膜中的脂质过氧化作用会产生大量醛类、醇类和酮类物质，其中一些已被证明具有细胞毒性。本研究确定了纯化的大鼠肝脏微粒体醛脱氢酶（ALDH）氧化醛类脂质过氧化产物的动力学参数。从雄性Sprague-Dawley大鼠获取肝脏，用于制备经400倍纯化的微粒体ALDH。在存在NAD+的情况下，测定了碳链长度为三至九个碳的饱和醛和不饱和醛的动力学参数Vmax和V/K。在所检测的醛类中，只有丙烯醛和4-羟基壬烯醛未被ALDH氧化。饱和醛系列的Vmax值（每分钟每毫克蛋白质产生的μmol NADH）随碳链长度呈线性增加，范围为6.5至23，不饱和醛的Vmax值范围为4.0至9.0。亲和常数V/K（每分钟每毫克蛋白质产生的nmol NADH/每升nmol醛）也随碳链长度增加，饱和醛的范围为12至9000，不饱和醛的范围为13至5300。这些结果表明，微粒体ALDH可能在微粒体膜脂质过氧化产生的活性醛解毒过程中发挥生物学作用。
