The purpose of this study is to probe the mechanism by which dexamethosone inducible cytochrome P-450 and P-450a convert testosterone to the metabolite 17 beta-hydroxy-4,6- androstadiene-3-one (delta 6T). Previous work in this laboratory, which showed that delta 6T formation paralleled 6-beta- hydroxylation, suggested that the same P-450 isozyme(s) are involved and a dual hydrogen atom abstraction mechanism was proposed. An analogous metabolite of valproate has also been reported. The objective of this work is to measure the deuterium isotope effects associated with the desaturation mechanism. Selectively deuterated testosterone derivatives are being synthesized and will be subjected to metabolism by dexamethasone induced microsomes and preparations derived form COS cell cultures transfected with P-450a c-DNA.
