Study on the mechanism of biosynthesis of 19-nor-stenroids and its application for analysis of pathgeneeis

我们已经证明了11-脱氧皮质酮(DOC)在体外牛肾上腺皮质中存在另一种代谢途径：对11&lt；β&gt；-，18-和19-羟化活性的DOC---19-OH-DOC---19-oxo-DOC---19-oic-DOC.Comparative研究表明，在DOC的19-羟化以及11&lt；β&gt；-和18-羟化反应中观察到了相当程度的羟化速率。此外，19位上的19-羟基-DOC和19-氧代-DOC的氧化反应速率约为DOC 19-羟基化的5倍。这些结果表明DOC的C-19氧化途径是存在的，尽管19-OH-DOC和19oxo-DOC对酶(S)的亲和力低于DOC。还证实了这些氧化反应需要还原的吡啶核苷酸和分子氧。此外，一氧化碳或甲草酮(0.01-1.0；microrn&gt；M)能与细胞色素P-450特异结合，而氰化钾(0.01-0.1 mM)则不影响这三种氧化反应。这些结果表明，细胞色素P-450可能参与DOC、19-OH-DOC和19-OIC-DOC的C-19氧化反应。我们还表明，19-OIC-DOC是DOC在肾上腺中代谢的最终产物，它可能进一步在肾上腺外转化为19-Nor-DOC。

We have demonstrated the presence of an alternative metabolic pathway of 11-deoxycorticosterone(DOC) in bovine adrenal cortex in vitro: DOC---19-OH-DOC---19-oxo-DOC---19-oic-DOC.Comparative studies of 11<beta>-, 18-, and 19-hydroxylation activities of reveled that an appreciable level of hydroxylation rate was observed in 19-hydroxylation of DOC, as well as in 11<beta>-, and 18-hydroxylations. In addition,the rates of the oxidation reactions of 19-OH-DOC and 19-oxo-DOC at the 19-position were about 5 times higher than those of the 19-hydroxylation of DOC. These resultus suggest the presence of the pathway of the C-19 oxidation of DOC, although the affinities of 19-OH-DOC and 19oxo-DOC for the enzyme(s) were lower than that of DOC.It was also established that reduced pyridine nucleotibe(NADPH) and molecular oxygen were required for these oxidation reactions. In addition, these three oxidation reactions were uniformly inhibited by the presence of carbon monoxide or metyrapone(0.01-1.0<micrn>M), which is known to bind Specifically with cytochrome P-450, while potassium cyanide(0.01-0.1mM) did not affect them. These results suggest the possibility of the inbolbe-ment of cytochrome P-450 in the C-19 oxidation reactions of DOC,19-OH-DOC and 19-oic-DOC. We have also shown that 19-oic-DOC is the final product of the metabolism of DOC in the adrenal gland and that it may further be converted to 19-nor-DOC extraadrenally.