Properties and Mchanisms of Lipid Peroxidation in Fish Skin

从新鲜沙丁鱼皮组织中提取不耐热的促氧化物质，以阐明沙丁鱼皮在捕获后迅速产生特殊鱼腥味的脂肪氧化机理。该峰在SDS-聚丙烯酰胺凝胶电泳法上呈单一条带。分子量估计约为18000道尔顿。这是一种促氧化物质。氧化专一的Z，Z-1，4-戊二烯结构的多不饱和脂肪酸。然而，不仅游离脂肪酸被有效地氧化，而且三酰甘油等酯类脂肪也被有效地氧化。对亚油酸氧化产物的分析表明，该反应具有较高的选择性，在8种可能的过氧化氢异构体中，主要生成了13(S)-过氧化氢。这些结果表明，沙丁鱼皮中的促氧化剂是一种含血红素的脂氧合酶。推测该酶参与了鱼腥味的产生，因为该酶具有催化亚油酸生成己醛的过氧化氢酶活性。

The heat-labile prooxidant substances were extracted an from fresh sardine(Sardinops melanosticta)skin tissues to elucidate the lipid oxidation mechanisms in sardine skin where the specific fishy odors are generated quickly after catch.The chromatography on several columns gave a prooxidant peak with a typical absorption spectrum of heme protein. This peak gave a single band on SDS polyacrylamide gel electrophoresis. The molecular weight was estimated to be approximately 18000 daltons.This prooxidant substance. oxidized exclusively polyunsaturated fatty acids with Z, Z-1, 4-pentadiene structure. However, not only free fatty acids but ester lipids such as triacylglycerols were oxidized efficiently. The analysis of oxidation products from linoleic acid revealed the high selectivity of the reaction which primarily gave 13(S)-hydroperoxide among 8 possible hydroperoxide isomers. These results showed that the prooxidant in sardine skin is a heme-containing lipoxygenase. The involvement of this enzyme in fishy odor generation was suggested because the hydroperoxidelyase activity to form hexanal from linoleic acid was found in the enzyme.