BIS-ALLYLIC HYDROXYLATION OF POLYUNSATURATED FATTY-ACIDS BY HEPATIC MONOOXYGENASES AND ITS RELATION TO THE ENZYMATIC AND NONENZYMATIC FORMATION OF CONJUGATED HYDROXY FATTY-ACIDS
BIS-ALLYLIC HYDROXYLATION OF POLYUNSATURATED FATTY-ACIDS BY HEPATIC MONOOXYGENASES AND ITS RELATION TO THE ENZYMATIC AND NONENZYMATIC FORMATION OF CONJUGATED HYDROXY FATTY-ACIDS
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DOI：
10.1006/abbi.1993.1059
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发表时间：
1993-01-01
影响因子：
3.9
通讯作者：
HAMBERG, M
中科院分区：
文献类型：
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作者：
OLIW, EH;BRODOWSKY, ID;HAMBERG, M
[14C]亚油酸与苯巴比妥诱导的大鼠肝微粒体一起孵育，并研究顺反共轭羟基脂肪酸的形成。鉴定出 13-羟基-9Z,11E-十八碳二烯酸 (13-HODE)、9-羟基-10E,12Z-十八碳二烯酸 (9-HODE) 和三种新的代谢物，即。 1 1-羟基-9Z,12Z-十八碳二烯酸(li-HODE)、8-HODE和14-HODE。主要产物11-HODE (59%R)不稳定，在酸性介质中转化为9(R,S)-HODE和13(R,S)HODE。所有代谢物均含有来自 O2 的氧。在氧气-18气体下的实验表明，13-HODE和9-HODE含有与其他代谢物相同或更少量的氧气-18。在前一种情况下，9-HODE和13-HODE以立体选择性(80-82%R)形成。 [11S-2H]亚油酸代谢为 13R-HODE，丢失了氘 (24%2H)，代谢为 9R-HODE，保留了氘 (95%2H)，而 [11R-2H]亚油酸代谢为 13R-HODE，大部分保留了标记 (71%2H) 和 9R-HODE，丢失了大部分标记(22%2H)。这些数据表明P450催化C11处的pro-R氢的提取、C9处的双键迁移和表面氧插入以产生9R-HODE，而C11处的pro-S氢的提取、随后双键迁移和氧插入产生13R-HODE。食蟹猴的肝微粒体如上所述将 18:2n-6 代谢为 13-羟基二十碳四烯酸，可能与 li-HODE 类似地形成。总之，P450生物合成顺反共轭羟基脂肪酸的一种机制涉及表面氢提取和氧插入。此外，不稳定的双烯丙基羟基代谢物的水解可能有助于形成共轭羟基脂肪酸。
[14C]Linoleic acid was incubated with phenobarbital-induced rat liver microsomes and formation ofcis-trans-conjugated hydroxy fatty acids was investigated. 13-Hydroxy-9Z,11E-octadecadienoic acid (13-HODE), 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE), and three novel metabolites were identified, viz. 1 1-hydroxy-9Z,12Z-octadecadienoic acid (li-HODE), 8-HODE, and14-HODE. 11-HODE (59%R), the main product, was unstable and converted to 9(R,S)-HODE and 13(R,S)HODE in acidic media. All metabolites contained oxygen from O2. Experiments under oxygen-18 gas showed that 13-HODE and 9-HODE contained equal or less amounts of oxygen-18 than the other metabolites. In the former case, 9-HODE and 13-HODE were formed with stereo-selectivity (80-82%R). [11S-2H]Linoleic acid was metabolized to 13R-HODE with loss of deuterium (24%2H) and to 9R-HODE with deuterium retention (95%2H), while [11R-2H]linoleic acid was metabolized to 13R-HODE that largely retained the label (71%2H) and to 9R-HODE that lost most of the label (22%2H). These data indicated that P450 catalyzed abstraction of thepro-Rhydrogen at C11, double bond migration and suprafacial oxygen insertion at C9 to give 9R-HODE, while abstraction of thepro-Shydrogen at C11, followed by double bond migration and oxygen insertion, yielded 13R-HODE. Hepatic microsomes of the cynomolgus monkey metabolized 18:2n-6 as above and 20:4n-6 to 13-hydroxyeicosatetraenoic acid, likely formed in analogy with li-HODE. In summary, one mechanism in the biosynthesis ofcis-trans-conjugated hydroxy fatty acids by P450 involves suprafacial hydrogen abstraction and oxygen insertion. In addition, hydrolysis of the unstable bis-allylic hydroxy metabolites may contribute to the formation of conjugated hydroxy fatty acids.