【摘要】 <正> 柞蚕(Antheraea pernyi G.)在我国蚕业生产中占有重要地位,防治其病虫害主要靠农药。因此研究蚕体内与农药代谢有关的酶类是有意义的。 微粒体多功能氧化酶系(MFO)起着代谢杀虫剂的中心作用,并与杀虫剂的选择毒性,抗性以及增效现象密切相关。细胞色素P-450(下简称P-450)是MFO的关键成分,更多还原

【Abstract】 (Ⅰ) Cytochrome P-450The difference spectrum obtained by passing carbon monoxide through a suspension of dithionite-reduced microsomes from oak silkworm (A. pernyi) midgut showed a sharp Peak at 448nm. With oxidized cytochrome P-450, a typical type Ⅱ difference spectrum (peak at 424 nm, trough at 398 or 404 nm) was obtained with pyridine.The effects of dithionite and piperonyl butoxide (PB) or piperonyl aldoxine (PA) on the pyridine-cytochrome P-450 difference spectrum were examined. The addition of dithionite resulted in an increase in the peak absorbance at 424 nm. When PB or PA was included with dithionite during incubation of the microsomes, the magnitude of the subsequently formed pyridine difference spectrum was markedly raised. Cytochrome P-450 level of oak silkworm was apparently decrease by treatment with PB in vitro.(Ⅱ) AmidaseSignificant levels of amidase activity were found in the microsomes from the fat body and midgut of larvae of the silkworm using N-methyl caproamide as substrate. Some properties of fat body amidase were summarized as follows:(1) Two pH optimum values of 7.5 and 9.5 were observed when the activity for N-methyl caproamide is plotted against pH. The Km values for N-methyl caproamide are similar at two optimum pH values.(2) The amidase was completedly suppressed by the sulfhydryl inhibitor p-chloro-mercuribenzoic acid (1×10-3M), thus indicating a requirement for a free sulfhydryl group. No stimulation of enzyme activity was observed by various bivalent cations such as Ca++, Co++,Mn++ and Mg++, at 1 × 10-6M.更多还原