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  • Title: A sex-specific form of cytochrome P-450 catalyzing propoxycoumarin O-depropylation and its identity with testosterone 6 beta-hydroxylase in untreated rat livers: reconstitution of the activity with microsomal lipids.
    Author: Yamazoe Y, Murayama N, Shimada M, Yamauchi K, Nagata K, Imaoka S, Funae Y, Kato R.
    Journal: J Biochem; 1988 Nov; 104(5):785-90. PubMed ID: 3266213.
    Abstract:
    Characteristics of a typical male-dominant reaction, dealkylation of n-propoxycoumarin, in rat livers were studied in relation to microsomal testosterone 6 beta-hydroxylase. The depropylation was more than 10-fold higher in the liver of male than female adult rats, but the sex-related difference was eliminated by neonatal castration. Hypophysectomy of adult male rats, which decreased the rates of male-specific P-450-male-dependent reactions, increased the depropylation of propoxycoumarin, while the rate was decreased by either intermittent injection or continuous infusion of human growth hormone to hypophysectomized rats. With regard to age-related difference, microsomal depropylation was detectable at neonate and reached a maximal level at 14 to 20 d of age, but was abruptly diminished only in female rats at puberty. These changes are in good agreement with those of testosterone 6 beta-hydroxylation and the content of a male-specific P-450(6)beta-1/PB-1. In reconstituted systems using extracted microsomal lipids, P-450(6)beta-1/PB-1 and P-450-male catalyzed the depropylation of propoxycoumarin. However, the microsomal depropylation was inhibited by antibodies which recognize P-450(6)beta-1/PB-1, but not P-450-male. These results indicate that microsomal depropylation of propoxycoumarin is catalyzed mainly by a male-specific P-450(6)beta-1/PB-1 in livers of untreated rats.
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