Acta Entomologica Sinica (1999) 42, 347-352

Xinghui Qiu and Xinfu Leng (1999)
[O-demethylase activity of cotton bollworm (Helicoverpa armigera) larvae: optimal assay conditions and inducibility by phenobarbital]
Acta Entomologica Sinica 42 (4), 347-352
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°C . 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 750g supernatant as enzyme source. Km and Vmax of O-demethylation of pNA estimated were 1.23mmol/L and 2.54nmol p-nitro-phenol 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.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
(original language: Chinese)
Database assignments for author(s): Xinghui Qiu

Research topic(s) for pests/diseases/weeds:
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Helicoverpa armigera