蝗虫（沙漠蝗）卵巢中蜕皮激素生物合成过程中C-2位羟基化的机制。
Mechanism of hydroxylation at C-2 during the biosynthesis of ecdysone in ovaries of the locust, Schistocerca gregaria.
作者信息
Greenwood D R, Dinan L N, Rees H H
出版信息
Biochem J. 1984 Feb 1;217(3):783-9. doi: 10.1042/bj2170783.
The stereochemistry of hydroxylation at C-2 during the biosynthesis of ecdysone in the ovaries of Schistocerca gregaria was investigated by incorporation of [1 alpha,2 alpha-3H(n)]cholesterol in admixture with [4-14C]cholesterol into oöcyte 2-deoxyecdysone and ecdysone conjugates in maturing adult female S. gregaria. Extraction of the eggs followed by enzymic hydrolysis of the ecdysteroid conjugate fraction yielded free ecdysteroids, from which 2-deoxyecdysone and ecdysone were purified. The 3H/14C ratios in the 2-deoxyecdysone and ecdysone were similar, suggesting that the 2 alpha hydrogen of cholesterol was retained during hydroxylation at C-2. This was corroborated by oxidation at C-2 of the 3,22-diacetate derivative of the ecdysone, yielding the corresponding 2-oxo compound with removal of essentially all the 3H originally present at the 2 alpha position of cholesterol. The results indicate that the 2 beta hydrogen of cholesterol has been eliminated during the hydroxylation at C-2. Thus, during ecdysone biosynthesis, hydroxylation at C-2 is direct and occurs with retention of configuration.
通过将[1α,2α-3H(n)]胆固醇与[4-14C]胆固醇混合掺入成年雌性沙漠蝗成熟过程中的卵母细胞2-脱氧蜕皮激素和蜕皮激素缀合物中，研究了沙漠蝗卵巢中蜕皮激素生物合成过程中C-2位羟基化的立体化学。提取卵后，对蜕皮甾类缀合物部分进行酶水解，得到游离的蜕皮甾类，从中纯化出2-脱氧蜕皮激素和蜕皮激素。2-脱氧蜕皮激素和蜕皮激素中的3H/14C比值相似，表明胆固醇的2α氢在C-2位羟基化过程中得以保留。蜕皮激素的3,22-二乙酸酯衍生物在C-2位氧化，生成相应的2-氧代化合物，同时基本上除去了最初存在于胆固醇2α位的所有3H，这证实了上述结果。结果表明，胆固醇的2β氢在C-2位羟基化过程中已被去除。因此，在蜕皮激素生物合成过程中，C-2位的羟基化是直接发生的，并且构型得以保留。
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