Esselman W J, Clagett C O
J Lipid Res. 1974 Mar;15(2):173-8.
Alfalfa seeds and seedlings contain an enzyme that catalyzes a reaction with the 13- and 9-hydroperoxides of linoleic acid to form 13-hydroxy-10-oxo-trans-octadecenoic acid and 9-hydroxy-12-oxo-trans-10-octadecenoic acid, respectively. When commercial lipoxygenase is used to generate the hydroperoxides, the above acids appear in about 2:1 proportions, respectively. The products of the action of the enzyme on the hydroperoxides were stabilized for analysis by reduction with H(2) and LiAIH(4). Trimethylsilyl derivatives of reduced products were analyzed by combined gas-liquid chromatography-mass spectrometry. Specific deuterium labeling permitted definite location of the oxo functions. (18)O(2) labeling experiments showed that the oxygens of both the oxo and the hydroxyl functions were derived from the hydroperoxide. Retention of both oxygens suggests that the reaction proceeds through a cyclic epiperoxide followed by a ketohydroxy-forming rearrangement. No products of hydroperoxide isomerase were found in reactions catalyzed by the crude enzyme from alfalfa seeds.
苜蓿种子和幼苗含有一种酶，该酶催化与亚油酸的13-和9-氢过氧化物发生反应，分别形成13-羟基-10-氧代反式十八碳烯酸和9-羟基-12-氧代反式-10-十八碳烯酸。当使用商业脂氧合酶生成氢过氧化物时，上述酸分别以约2:1的比例出现。通过用H(2)和LiAIH(4)还原，使该酶作用于氢过氧化物的产物稳定化以便分析。通过气液色谱-质谱联用分析还原产物的三甲基硅烷基衍生物。特定的氘标记确定了氧代官能团的位置。(18)O(2)标记实验表明，氧代官能团和羟基官能团的氧均来自氢过氧化物。两个氧原子的保留表明该反应通过环状环氧化物进行，随后是形成酮羟基的重排。在苜蓿种子粗酶催化的反应中未发现氢过氧化物异构酶的产物。
