이물질 대사에 관여하는 cytochrome P-450(P-450) 의존성 효소들은 동물 조직에서 microsome을 분리한 후 냉장고에 장기 보존하면서 연구 목적에 따라 microsomal monooxygenase 활성도를 관찰하는 경우가 적지 않다. 따라서 ${eta}$-naphthoflavone을 처리한 흰 쥐의 간 microsome을 $-80^{circ}C$에서 보존하면서 P-450, cytochrome $b_5(b_5$), 몇 종류의 cytochrome P-450-dependent monooxygenase와 NADPH-cytochrome P-450 reductase 둥의 안정성을 검토하였다. P-450과 $b_5$의 함량은 변화를 보이지 않았으며 aryl hydrocarbone hydroxylase, 7-ethoxycoumarin O-deethylase와 benzphetamine demethylase의 활성도 역시 변화가 없었으나 NADPH-cytochrome P-450 reductase의 활성도는 저장 4개월 이후 점차 증가하였다. 한편 testosterone $16{alpha}$-hydroxylase를 포함한 testosterone의 hydroxylase들은 저장 5개월 후부터 점차로 감소하였는데 이는 P-450의 testosterone 결합분위의 어떤 변화 때문인 것으로 생각된다.
The stability of cytochrome P-450, cytochrome $b_5$, cytochrome P-450-dependent monooxygenases, and NADPH-cytochrome P-450 reductase was observed in liver microsomes prepared from rats pretreated with ${eta}$-naphthoflavone during the stored period of 8 months at $-80^{circ}C$ The contents of P-450 and $b_5$ were not changed significantly and the activities of aryl hydrocarbon hydroxylase, 7-ethoxycoumarin O-deethylase, and benzphetamine demethylase were also stable for this period. However, the activities of NADPH-cytochrome P-450 reductase were increased gradually, whereas since 5th month, those of testosterone hydroxylases including $16{alpha}$-hydroxylase were decreased. The decrease seems due to a certain change in testosterone binding site of P-450, not to the inactivation of one isozyme of P-450.
