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dc.contributor.authorL. Prapanthadaraen_US
dc.contributor.authorN. Promteten_US
dc.contributor.authorS. Koottathepen_US
dc.contributor.authorP. Somboonen_US
dc.contributor.authorA. J. Kettermanen_US
dc.contributor.otherChiang Mai Universityen_US
dc.contributor.otherFaculty of Medicine, Chiang Mai Universityen_US
dc.contributor.otherMahidol Universityen_US
dc.identifier.citationInsect Biochemistry and Molecular Biology. Vol.30, No.5 (2000), 395-403en_US
dc.description.abstractPreviously we have purified and characterized a major glutathione S- transferase (GST) activity, GST-4a, from the Thai mosquito Anopheles dirus B, a model mosquito for study of anopheline malaria vectors [Prapanthadara, L. Koottathep, S., Promtet, N., Hemingway, J. and Ketterman, A.J. (1996) Insect Biochem. Mol. Biol. 26:3, 277-285]. In this report we have purified an isoenzyme, GST-4c, which has the greatest DDT-dehydrochlorinase activity. Three additional isoenzymes, GST-4b, GST-5 and GST-6, were also partially purified and characterized for comparison. All of the Anopheles GST isoenzymes preferred 1-chloro-2,4-dinitrobenzene (CDNB) as an electrophilic substrate. In kinetic studies with CDNB as an electrophilic substrate, the V(max) of GST-4c was 24.38 ╬╝mole/min/mg which was seven-fold less than GST- 4a. The two isoenzymes also possessed different K(m)s for CDNB and glutathione. Despite being only partially pure GST-4b had nearly a four-fold greater V(max) for CDNB than GST-4c. In contrast, GST-4c possessed the greatest DDT-dehydrochlorinase specific activity among the purified insect GST isoenzymes and no activity was detected for GST-5. Seven putative GST substrates used in this study were not utilized by An. dirus GSTs, although they were capable of inhibiting CDNB conjugating activity to different extents for the different isoenzymes. Bromosulfophthalein and ethacrynic acid were the most potent inhibitors. The inhibition studies demonstrate different degrees of interaction of the An. dirus isoenzymes with various insecticides. The GSTs were inhibited more readily by organochlorines and pyrethroids than by the phosphorothioates and carbamate. In a comparison between An. dirus and previous data from An. gambiae the two anopheline species possess a similar pattern of GST isoenzymes although the individual enzymes differ significantly at the functional level. The available data suggests there may be a minimum of three GST classes in anopheline insects. (C) 2000 Elsevier Science Ltd.en_US
dc.rightsMahidol Universityen_US
dc.subjectAgricultural and Biological Sciencesen_US
dc.subjectBiochemistry, Genetics and Molecular Biologyen_US
dc.titleIsoenzymes of glutathione S-transferase from the mosquito Anopheles dirus species B: The purification, partial characterization and interaction with various insecticidesen_US
Appears in Collections:Scopus 1991-2000

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