Gardner W H
J Lipid Res. 1970 Jul;11(4):311-21.
Linoleic acid oxidation catalyzed by lipoxygenase (lipoxidase) activity in extracts of defatted corn germ does not terminate in the product, linoleic acid hydroperoxide, unless the lipoxygenase is first partially purified. If purification is not attempted, the hydroperoxide product exists only as a barely detectable intermediate in the synthesis of three products. One of these was identified as 9-hydroxy-10-oxo-cis-12-octadecenoic acid formed from the hydroperoxide by the enzyme, linoleate hydroperoxide isomerase. Another product, 13-hydroxy-10-oxo-trans-11-octadecenoic acid, is believed to be formed by an isomerase also. The third product was the linoleate ester of one of the hydroxy-oxo-fatty acids, 9-(cis-9,cis-12-octadecadienoyl)-10-oxo-cis-12-octadecenoic acid. It is not known if the synthesis of the ester is enzyme-catalyzed. When a mixture of 13-hydroperoxy-cis-9,trans-11-octa-decadienoic acid and 9-hydroperoxy-trans-10,cis-12-octa-decadienoic acid from soybean lipoxygenase oxidation of linoleic acid was used as a substrate, 13-hydroxy-12-oxo-cis-9-octadecenoic acid and 9-hydroxy-12-oxo-trans-10-octadecenoic acid were formed as the major products of catalysis by linoleate hydroperoxide isomerase(s) from corn. Smaller quantities of 9-hydroxy-10-oxo-cis-12-octadecenoic acid and 13-hydroxy-10-oxo-trans-11-octadecenoic acid were also formed.
在脱脂玉米胚芽提取物中，由脂氧合酶（脂肪氧化酶）活性催化的亚油酸氧化反应，除非脂氧合酶首先进行部分纯化，否则不会以亚油酸氢过氧化物作为反应产物而终止。如果不进行纯化，氢过氧化物产物仅作为三种产物合成过程中一种几乎检测不到的中间体存在。其中一种产物被鉴定为由该氢过氧化物通过亚油酸氢过氧化物异构酶形成的9-羟基-10-氧代-顺式-12-十八碳烯酸。另一种产物13-羟基-10-氧代-反式-11-十八碳烯酸据信也是由一种异构酶形成的。第三种产物是其中一种羟基-氧代脂肪酸的亚油酸酯，即9-（顺式-9,顺式-12-十八碳二烯酰基）-10-氧代-顺式-12-十八碳烯酸。目前尚不清楚该酯的合成是否由酶催化。当使用由大豆脂氧合酶氧化亚油酸生成的13-氢过氧-顺式-9,反式-11-十八碳二烯酸和9-氢过氧-反式-10,顺式-12-十八碳二烯酸的混合物作为底物时，13-羟基-12-氧代-顺式-9-十八碳烯酸和9-羟基-12-氧代-反式-10-十八碳烯酸是玉米亚油酸氢过氧化物异构酶催化反应的主要产物。同时还生成了较少量的9-羟基-10-氧代-顺式-12-十八碳烯酸和13-羟基-10-氧代-反式-11-十八碳烯酸。
