ブタ副腎ミクロソームのステロイド17α-ヒドロキシラーゼ-C_<17,20>リアーゼ(チトクロームP-450) : プロゲステロンによるリアーゼ活性の阻害と17α-ヒドロキシプロゲステロンによるヒドロキシラーゼ活性の阻害

概要

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Highly purified 17α-hydroxylase-C_<17,20> lyase (cytochrome P-450) from porcine adrenocortical microsomes was incubated with [4-^<14>C]-C_<21>-steroid substrate in the presence of cytochrome P-450 reductase and nicotinamide adenine dinucleotide phosphate as a cofactor. On the kinetic analysis, C_<17,20> lyase activity was strongly inhibited by progesterone. The inhibition was competitive, and K_1 value for progesterone was 0.9μM. In addition, 17α-hydroxylase activity was inhibited by 17α-hydroxyprogesterone. The inhibition was competitive, and K_1 value for 17α-hydroxyprogesterone was 7.5μM. These results suggest that both hydroxylase and lyase reactions are catalyzed on a single active site.
公益社団法人日本薬学会の論文
1985-01-25