Oliw E H, Sprecher H W
Department of Pharmaceutical Pharmacology, Uppsala Biomedicinska Centrum, Uppsala University, Sweden.
Biochim Biophys Acta. 1991 Nov 27;1086(3):287-94. doi: 10.1016/0005-2760(91)90172-e.
Monooxygenases of monkey seminal vesicles can metabolize arachidonic acid (20:4(n-6)) by w3-hydroxylation to 18(R)-hydroxyeicosatetraenoic acid (18(R)-HETE) and eicosapentaenoic acid (20:5(n-3)) to 17,18-dihydroxyeicosatetraenoic acid (Oliw, E.H. (1989) J. Biol. Chem. 264, 17845-17853). The present study aimed to further characterize the oxygenation of (n-3) polyunsaturated fatty acids. 14C-Labelled 22:6(n-3), 20:5(n-3), 20:4-(n-3) and 18:3(n-3) were incubated with microsomes of seminal vesicles of the cynomolgus monkey, NADPH and a cyclooxygenase inhibitor, diclofenac, and the main metabolites were identified by capillary gas chromatography-mass spectrometry. 22:6(n-3) was slowly metabolized to 19,20-dihydroxy-4,7,10,13,16-docosapentaenoic acid, while 20:5(n-3), 20:4(n-3) and 18:3(n-3) were metabolized more efficiently to the corresponding w4,w3-diols. The w3 epoxides, which were obtained from 20:5(n-3) and 18:3(n-3), were isolated in the presence of an epoxide hydrolase inhibitor, 1(2)epoxy-3,3,3-trichloropropane, and the geometry of the epoxides was determined to be 17S, 18R and 15S, 16R, respectively. While 20:5(n-3) was metabolized almost exclusively to the epoxide and diol pair of metabolites, 18:3(n-3) was metabolized not only to the w3 epoxide and the corresponding diol, but also to the w2 alcohol, 17(R)-hydroxy-9,12,15-octadecatrienoic acid. 22:6(n-3) and 5,8,11,14-eicosatetraynoic acid inhibited the biosynthesis of 18(R)-HETE from arachidonic acid (IC50 0.16 and 0.14 mM, respectively). In comparison with 20:4 or 18:3(n-3), 18:1(n-9) and 22:5(n-6) appeared to be slowly metabolized by seminal monooxygenases, while 18:2(n-6) was converted to the w3 alcohol and to smaller amounts of the w2 alcohol (4:1). Together, the results indicate that the w3-hydroxylase and w3-epoxygenase enzyme(s) metabolize 20:4(n-6) and 20:5(n-3) almost exclusively to the w3(R) alcohol and the w3(R, S) epoxide, respectively, while longer and shorter fatty acids either are poor substrates or metabolized with a lesser degree of position specificity.
猕猴精囊中的单加氧酶可通过ω3-羟基化作用将花生四烯酸（20:4(n-6)）代谢为18(R)-羟基二十碳四烯酸（18(R)-HETE），并将二十碳五烯酸（20:5(n-3)）代谢为17,18-二羟基二十碳四烯酸（奥利夫，E.H.（1989年）《生物化学杂志》264卷，17845 - 17853页）。本研究旨在进一步表征(n-3)多不饱和脂肪酸的氧化作用。将14C标记的22:6(n-3)、20:5(n-3)、20:4-(n-3)和18:3(n-3)与食蟹猴精囊的微粒体、NADPH以及环氧化酶抑制剂双氯芬酸一起孵育，并通过毛细管气相色谱-质谱法鉴定主要代谢产物。22:6(n-3)缓慢代谢为19,20-二羟基-4,7,10,13,16-二十二碳五烯酸，而20:5(n-3)、20:4(n-3)和18:3(n-3)更有效地代谢为相应的ω4,ω3-二醇。从20:5(n-3)和18:3(n-3)得到的ω3环氧化物在环氧水解酶抑制剂1(2)-环氧-3,3,3-三氯丙烷存在下被分离出来，并且环氧化物的几何构型分别确定为17S, 18R和15S, 16R。虽然20:5(n-3)几乎只代谢为环氧化物和二醇对代谢产物，但18:3(n-3)不仅代谢为ω3环氧化物和相应的二醇，还代谢为ω2醇，即17(R)-羟基-9,12,15-十八碳三烯酸。22:6(n-3)和5,8,11,14-二十碳四炔酸抑制花生四烯酸生成18(R)-HETE的生物合成（IC50分别为0.16和0.14 mM）。与20:4或18:3(n-3)相比，18:1(n-9)和22:5(n-6)似乎被精囊单加氧酶缓慢代谢，而18:2(n-6)转化为ω3醇和少量的ω2醇（比例为4:1）。总之,结果表明ω3-羟化酶和ω3-环氧化酶分别将20:4(n-6)和20:5(n-3)几乎只代谢为ω3(R)醇和ω3(R, S)环氧化物，而较长和较短的脂肪酸要么是不良底物，要么以较低的位置特异性程度进行代谢。
