Weusten J J, Legemaat G, van der Wouw M P, Smals A G, Kloppenborg P W, Benraad T
Department of Medicine, St. Radboud Hospital, University of Nijmegen, The Netherlands.
J Steroid Biochem. 1989 May;32(5):689-94. doi: 10.1016/0022-4731(89)90513-x.
The biochemical pathway leading to the 16-unsaturated C19 steroids--known as sex pheromone (precursors) in pig and man--is still a matter of dispute. In the 16-ene-synthetase process, via which 5,16-androstadien-3 beta-ol (ADL) or 4,16-androstadien-3-one (ADN) are biosynthesized from pregnenolone (P5) or progesterone (P4), a number of 2 or even 3 step conversions have been suggested in porcine tests, including 20 beta-reduction, 21-hydroxylation and 16,17-dehydrogenation. Studying the 16-ene-synthetase reaction in human testicular homogenates, we adduced evidence for the hypothesis that ADL is synthesized from P5 in a single step, not requiring separate intermediates. Our proposal for the 16-ene-synthetase mechanism also explains why, at least in our hands, synthesis of ADL is always accompanied by co-synthesis of its satellite 5-androstene-3 beta,17 alpha-diol (epiA5): both steroids are synthesized as a mere consequence of the fact that the proposed elimination and substitution reactions for the synthesis of ADL and epiA5, respectively, are competitive processes.
导致16-不饱和C19类固醇（在猪和人类中被称为性信息素（前体））的生化途径仍存在争议。在16-烯合成酶过程中，通过该过程可从孕烯醇酮（P5）或孕酮（P4）生物合成5,16-雄二烯-3β-醇（ADL）或4,16-雄二烯-3-酮（ADN），在猪的试验中已提出了一些2步甚至3步的转化过程，包括20β-还原、21-羟基化和16,17-脱氢。在研究人睾丸匀浆中的16-烯合成酶反应时，我们为以下假说提供了证据：ADL是由P5一步合成的，不需要单独的中间体。我们提出的16-烯合成酶机制也解释了为什么至少在我们的实验中，ADL的合成总是伴随着其卫星产物5-雄烯-3β,17α-二醇（epiA5）的共合成：这两种类固醇的合成仅仅是因为分别用于合成ADL和epiA5的消除和取代反应是竞争性过程。
