INCORPORATION OF LABEL FROM O-18(2) INTO ACETATE DURING SIDE-CHAIN CLEAVAGE CATALYZED BY CYTOCHROME P-450(17-ALPHA) (17-ALPHA-HYDROXYLASE-17,20-LYASE)
INCORPORATION OF LABEL FROM O-18(2) INTO ACETATE DURING SIDE-CHAIN CLEAVAGE CATALYZED BY CYTOCHROME P-450(17-ALPHA) (17-ALPHA-HYDROXYLASE-17,20-LYASE)
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DOI：
10.1039/p19940000263
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发表时间：
1994-02-07
期刊：
影响因子：
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通讯作者：
WRIGHT, JN
中科院分区：
文献类型：
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作者：
AKHTAR, M;CORINA, DL;WRIGHT, JN
已制备出在 C-21 甲基上氘代的孕烯醇酮和 17 α-羟基孕烯醇酮样品，并在 O-18(2) 下用猪睾丸微粒体制剂进行侧链裂解。 17 α-羟基孕烯醇酮完全裂解为脱氢异雄酮，并且发现在该过程中释放的乙酸掺入了 0.90 个 O-18 原子。当用孕烯醇酮进行类似的孵育时，两种甾体产物，脱氢异雄酮和androsta-5,16-dien-3 beta-ol，以大约1:2-3的比例形成，并且在该过程中形成的乙酸再次显示含有0.85-0.90个O-18原子；补充实验中，在 C-20 羰基上用 O-18 标记的两种底物在 O-16(2) 下孵育，得到保留了 65-85% 原始羰基氧的乙酸。实验强化了这样的假设：上述两个 C(17)-C(20) 键断裂对应于下式的酰基-碳裂变过程，显示了各种氧原子的指示命运：[图形]
Samples of pregnenolone and 17 alpha-hydroxypregnenolone deuteriated at the C-21 methyl group have been prepared and subjected to side-chain cleavage with a pig testes microsomal preparation under O-18(2). 17 alpha-Hydroxypregnenolone was exclusively cleaved to dehydroisoandrosterone and the acetic acid released during the process was found to incorporate 0.90 atom of O-18. When a similar incubation was performed with pregnenolone two steroidal products, dehydroisoandrosterone and androsta-5,16-dien-3 beta-ol, were formed in an approximate ratio of 1:2-3 and the acetic acid formed in the process was again shown to contain 0.85-0.90 atom of O-18; Complementary experiments in which the two substrates labelled with O-18 at the C-20 carbonyl group were incubated under O-16(2) gave acetic acid retaining between 65-85% of the original carbonyl oxygen. The experiments strengthen the hypothesis that the two C(17)-C(20) bond cleavages described above correspond to the acyl-carbon fission process of the equation below showing the indicated fate of the various oxygen atoms:[GRAPHICS]