Effects of lyophilization and storage of rat liver microsomes on activity of aniline hydroxylase, contents of cytochrome b5 and cytochrome P-450 and aniline-induced P-450 difference spectrum

Abstract

Effects of lyophilization and storage of rat liver 9,000 × g supernatant fraction or microsomes on activity of aniline hydroxylase, contents of cyt. P-450 and cyt. b5 and aniline-induced P-450 difference spectrum were studied. The lyophilization of rat liver 9,000 × g supernatant fraction or microsomes produced about 20% decrease in the activity of aniline hydroxylase. Aniline hydroxylase was stably stored for 6 months if lyophilized 9,000 × g supernatant fraction of rat liver had been stored in an atmosphere of nitrogen or in a low pressure of air. Activity of aniline hydroxylase and contents of cyt. P-450 and cyt. b5 were not reduced during aerobical storage for a week. When lyophilized microsomes were stored for 6 months anaerobically, aniline hydroxylase, cyt. P-450 and cyt. b5 were more stable as compared to aerobical storage. However, activity of aniline hydroxylase was reduced approx. 40% by the storage. The reduction of aniline hydroxylase activity was more significant than that of contents of cyt. P-450 and cyt. b5. Reduction of either activity of aniline hydroxylase or contents of cyt. P-450 and cyt. b5 was more marked when lyophilized microsomes were stored with glycerol. Aniline hydroxylase in lyophilized 9,000 × g supernatant fraction from phenobarbital treated rabbit was stably stored, and aerobically little activity was lost during storage for 7 months.