大鼠肝、肺脂氧合酶代谢8种化学物质的活性比较

Comparison of the Metabolic Activities of Lipoxygenases from Rat Liver and Lung towards 8 Chemicals

对大鼠肝、肺细胞液中脂氧合酶协同氧化 8种化学物质的活性进行比较研究。肝酶的适宜反应条件为Tris缓冲液、pH7 2、3 5mmol/L亚油酸和 2 13mg/L胞液蛋白 ;肺酶的适宜反应条件为Tris缓冲液、pH6 5、13 5mmol/L亚油酸和2 2 3mg/L胞液蛋白。抑制剂去甲二氢愈创木酸 (NDGA)对肝、肺脂氧合酶氧化联苯胺的反应均有明显抑制作用并呈剂量效应关系。除联苯胺外 ,四甲基联苯胺、邻苯三酚、愈创木酚、四甲基苯二胺、连氮双 ( 3-乙基苯并三唑 - 6 -磺酸 )、邻联 (二 )茴香胺和对苯二胺等 7种化学物质也被肝、肺脂氧合酶协同氧化。但肝酶活性仅相当于肺酶活性的 12 %～ 19%。认为出现这种差异的原因在于 :( 1)肝、肺组织中存在着不同的脂氧合酶同工酶 :( 2 )肝脂氧合酶所占胞液蛋白量的比例低、数量少。结果提示 :肝。

The activity of lipoxygenase from rat liver cytosol to co-oxidase 8 chemicals were compared with that of the enzyme from rat lung.The optimum reactive conditions were pH 7.2 in Tris buffer, 3.5 mmol linoleic acid/L and 213 mg cytosolic protein/L for the liver enzyme, and pH 6.5 in Tris buffer,13.5 mmol linoleic acid/L and 213 mg cytosolic protein/L for the lung enzyme.Benzidine co-oxidation by the enzymes from liver and lung was obviously inhibated by nordihydroquaiaretic acid (NDGA) in a concentration-dependent manner.Besides benzidine,tetramethylbenzidine, guaiacal, pyrogallol,tetramythyl-p-pheny lenediamine,azinobis (3-ethybenzothiazoline-6-sulfonic acid,o-dianisidine and p-phenylenediamine also co-oxidated by the enzymes. Bot the metabolic activity of liver enzyme was only equitvalent to 12%～19 % of lung's.The reasons for the difference may be:1. there are different lipoxygenase isozymes in liver and lung 2.the ratio and the amounl of liver enzyme in cytosolic protein are lower than that of lung enzyme. The results suggest that both lipoxygenases from liver and lune are involved in the oxidative processes of some chemicals that possess benzene ring structure and the enzymetic system is a important pathway of chemical metabolism in organisms.