Comparative Studies of Substrate and Inhibitor Specificity of Glutathione S-Transferases in Six Tissues of Oxya chinensis(Thunberg)(Orthoptera:Acrididae)

作     者：WU Hai-hua ZHU Kun-yan GUO Ya-ping ZHANG Xiao-min MA En-bo 

作者机构：Institute of Applied Biology Shanxi University Taiyuan 030006 P.R.China Department of Entomology Kansas State University Manhattan 66506 USA 

出 版 物：《Agricultural Sciences in China》 (中国农业科学（英文版）)

年 卷 期：2008年第7卷第4期

页      面：462-468页

学科分类：09[农学] 0904[农学-植物保护] 

基　　金：supported by the National Natural Science Foundation of China(30570247,30470219) Science and Technology Commission of Shanxi Province,China(041005,2006011075) 

主　　题：Oxya chinensis glutathione S-transferase (GST) tissue distribution kinetic parameters inhibition in vitro 

摘      要：Specific activity, substrate specificity, and kinetic parameters （Km and Vmax） of glutathione S-transferases （GSTs） towards three substrates, 1-chloro-2,4-dinitrobenzene （CDNB）, 1,2-dichloro-4-nitrobenzene （DCNB）, and p-nitrobenzene chloride （pNBC） were investigated in six tissues （foregut, midgut, hindgut, fat body, hemolymph, and muscle） of Oxya chinensis. In addition, the inhibition in vitro （ethacrynic acid, and Cibacron Blue 3GA） of Oxya chinensis in the six tissues was also investigated. Glutathione S-transferase activity was detected in all the six tissues examined. The rank order of GST activities towards CDNB was fat body 〉 midgut 〉 hindgut 〉 muscle 〉 foregut 〉 hemolymph both in females and males. Glutathione S-transferase activities in the fat body in females and males were 1.3- to 10.4-fold and 1.1- to 10.0- fold higher than those in the other tissues. The rank order of GST activities towards the other substrates changed slightly. From these results, it was inferred that GSTs in the fat body and midgut played important roles in detoxifying xenobiotics including insecticides and plant allelochemicals in O. chinensis. In the three substrates examined, CDNB seemed to be the best substrate, followed by pNBC and DCNB. The kinetic parameters of GSTs were different among the six tissues. This suggested that GSTs in different tissues have various affinities and catalytic efficiency to substrates. In vitro inhibition study showed that the median inhibition concentration （IC50） values of the two inhibitors to GSTs from the six tissues were different. The results suggested that the two inhibitors have different inhibition potency to GSTs from the different tissues. The observed changes in kinetic parameters and inhibition in vitro among the six tissues of the insect might suggest that the number and structure of isoenzymes and their rate of expression varied for the different tissues.