Hydroperoxide lyases (CYP74C and CYP74B) catalyze the homolytic isomerization of fatty acid hydroperoxides into hemiacetals
Hydroperoxide lyases (CYP74C and CYP74B) catalyze the homolytic isomerization of fatty acid hydroperoxides into hemiacetals
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DOI：
10.1016/j.bbalip.2006.09.002
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发表时间：
2006-12-01
影响因子：
4.8
通讯作者：
Hamberg, Mats
中科院分区：
文献类型：
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作者：
Grechkin, Alexander N.;Bruehlmann, Fredi;Hamberg, Mats
利用重组甜瓜（Cucumis梅洛L.）对CYP 74 C亚家族HPL进行了研究。在0 ℃下短时间（5 s-1 min）孵育，然后快速萃取和三甲基甲硅烷基化，使得有可能捕获新的不稳定（t（1/2）< 30 s）产物，即半缩醛（1 ′ E，3 ′ Z）-9-羟基-9-（1 ′，3 ′-壬二烯基氧基）-壬酸。通过GC-MS分析进行鉴定，并通过催化氢化后形成三甲基甲硅烷基9-三甲基甲硅烷基氧基-9-壬氧基-壬酸酯和H-2-标记实验进行证实。[O-18（2）-hydroperoxy]9-HPOD的两个O-18原子都被引入半缩醛中。沿着半缩醛，三种链断裂产物，即烯醇（1 E，3 Z）-壬二烯醇和3（Z）-壬烯醛与9-氧代壬酸的水合物，作为它们的三甲基硅基衍生物被捕获。[O-18（2）]9-HPOD的O-18掺入动力学为裂解产物来源于半缩醛提供了有力的证据。亚麻酸和亚油酸13-氢过氧化物作为重组HPLs的甜瓜，苜蓿（苜蓿）和番石榴（番石榴）的底物，并在每种情况下，半缩醛和烯醇可检测的捕获技术。获得的数据表明，CYP 74 C和CYP 74 B HPL作为异构酶，将脂肪酸氢过氧化物均裂重排为短寿命的半缩醛，其在分解时产生3（Z）-壬烯醛、3（Z）-己烯醛和其他短链醛。(c)2006 Elsevier B. V.保留所有权利。
The conversion of linoleic acid 9-hydroperoxide (9-HPOD) by recombinant melon (Cucumis melo L.) hydroperoxide lyase (HPL, CYP74C subfamily) was studied. Short (5 s-1 min) incubations at 0 degrees C followed by rapid extraction and trimethylsilylation made it possible to trap a new unstable (t(1/2) < 30 s) product, i.e. the hemiacetal (1'E,3'Z)-9-hydroxy-9-(1',3'-nonadienyloxy)-nonanoic acid. Identification was performed by GC-MS analysis and substantiated by the formation of trimethylsilyl 9-trimethylsilyloxy-9-nonyloxy-nonanoate upon catalytic hydrogenation and by H-2-labelling experiments. Both O-18 atoms of [O-18(2)-hydroperoxy]9-HPOD were incorporated into the hemiacetal. Along with the hemiacetal, three chain-cleavage products, i.e. the enol (1E,3Z)-nonadienol and the hydrates of 3(Z)-nonenal and 9-oxononanoic acid, were trapped as their trimethylsilyl derivatives. The kinetics of O-18 incorporation from [O-18(2)]9-HPOD provided strong evidence that the cleavage products originated in the hemiacetal. Linolenic and linoleic acid 13-hydroperoxides served as substrates for recombinant HPLs of melon, alfalfa (Medieago sativa) and guava (Psidium guajava), and in each case hemiacetals and enols were detectable by the trapping technique. The data obtained demonstrated that CYP74C and CYP74B HPLs act as isomerases performing a homolytic rearrangement of fatty acid hydroperoxides into short-lived hemiacetals which upon decomposition produce 3(Z)-nonenal, 3(Z)-hexenal and other short chain aldehydes. (c) 2006 Elsevier B.V. All rights reserved.