›› 1999, Vol. 42 ›› Issue (4): 347-352.

• 研究论文 • 上一篇    下一篇

棉铃虫幼虫中肠微粒体P450差光谱与O-脱甲基酶的酶学特征及其可诱导性

邱星辉, 冷欣夫   

  • 出版日期:1999-11-20 发布日期:1999-11-20

O-DEMETHYLASE ACTIVITY OF COTTON BOLLWORM (HELICOVERPA ARMIGERA) LARVAE:OPTIMAL ASSAY CONDITIONS AND INDUCIBILITY BY PHENOBARBITAL

Qiu Xing-hui,Leng Xin-fu   

  • Online:1999-11-20 Published:1999-11-20

摘要: 棉铃虫Helicoverpa armigera (Hübner)幼虫中肠微粒体制备液的CO差光谱在450 nm有吸收峰,P450含量为(687±11) pmol/mg。中肠750 g离心的上清液的O-脱甲基酶活性在酶量相当5个中肠、反应时间30 min内与酶量和反应时间呈线性关系;最适Ph值在7.8, 最适温度为20~25℃。酶系对底物对硝基苯甲醚的O-脱甲基活性的Km=1.23 mmol/L, Vmax=2.54 nmol对硝基酚/(mg·min)。NADPH为酶活的重要因子,离体测定时,O-脱甲基酶在无外来NADPH的活性仅为加0.25 mmol/L NADPH 的16%。在反应体系中加入1.5% BSA明显促进产物的生成。P450的专一性抑制剂PBO浓度达到1 mmol/L时,可抑制酶90%的活性。棉铃虫取食含0.25%苯巴比妥钠的食物72 h后,O-脱甲基酶活性是对照组的1.73倍。

关键词: P450, O-脱甲基酶, 诱导作用, 苯巴比妥, 棉铃虫

Abstract: CO-difference spectrum of midgut microsome preparation with P450 content of (687±11) pmol/mgPr. Showed absorbance peak at 450nm. O-demethylase of pnitroanisile(pNA) was maximally active at pH 7.8 and temperature 20~25℃. Activity was linear with respect to time for up to 30min, and with respect to enzyme level for up to 5 tissue equivalents/ incubation with 750 g supernatant as enzyme source. Km and Vmax of O-demethylation of pNA estimated were 1.23 mmol/L and 2.54nmol p-nitrophenol formed/mgPr/min. respectively. NADPH was one of the requirements for the O-demethylation of pNA, the activity without external NADPH is 16% as that of with 0.25mmol/L NADPH. 1.5% BSA added in the incubation mixture enhanced (1.2 folds) the production of p-nitrophenol. PBO (1 mmol/L) strikingly (90%) inhibited O-demethylation.1.73 folds induction of O-[demethylase activity was observed by dietary 0.25% PB.

Key words: P450 monooxygenase, O-demethylase activity, induction, phenobarbital, Helicoverpa armigera