单宁酸对杨小舟蛾谷胱甘肽S-转移酶活性的诱导

Induction of glutathione S-transferases by tannic acid in Micromelalopha troglodyta

利用分光光度酶动力学的方法,确定杨小舟蛾Micromelalopha troglodyte(Graeser)谷胱甘肽S-转移酶(GSTs)的最适反应条件,并进一步研究单宁酸对杨小舟蛾GSTs活性的诱导。结果表明:杨小舟蛾GSTs测定的最适反应pH为6.5,最适反应温度为25℃。杨小舟蛾GSTs的米氏常数(KmCDNB和KmGSH)为2.63±2.32和0.61±0.10mmol/L,最大反应速度(VmaxCDNB和Vmax GSH)分别为556.26±380.02和234.12±12.84nmol/(min.mg)。单宁酸对杨小舟蛾GSTs诱导具有明显的剂量效应和时间效应关系。有效成分为0.01,0.05,0.10,0.50和1.00mg/mL的单宁酸作用48h后,杨小舟蛾体内GSTs活性分别增加了1.13,0.89,0.94,0.86和0.85倍;同样有效成分的单宁酸作用72h后,杨小舟蛾GSTs活性分别增加了1.49,1.06,1.55,1.63和0.93倍;而作用96h后,GSTs活性则分别增加了2.04,1.61,1.12,1.56和2.03倍。

The optimum reaction condition of glutathion S-transferases （GSTs） and the induction of GSTs by tannic acid were investigated in Micromelalopha troglodyta （Graeser）using the methods of biochemistry. The results showed that the optimum pH value of GSTs was 6.5, and the optimum temperature 25 ℃ for GSTs in M. troglodyta. The Michaelis constants （KmCDNB and KmGSH ） of GSTs hydrolyzing CDNB and GSH were 2.63 ± 2.32 and 0.61 ± 0.10 mmol/L, and the maximum velocities （ VmaxCDNB and VmaxGSH ） hydrolyzing CDNB and GSH were 556.26 ± 380.02 and 234.12 ± 12.84 nmol/（min·mg）. Furthermore, the dosage- and time-effect of induction of GST activity in M. troglodyta by tannic acid were investigated. The results showed that the GST activity increased 1.13 （1.49, 2.04）-, 0.89 （1.06, 1.61）-, 0.94 （1.55, 1.12）-, 0.86 （1.63, 1.56）-, and 0.85 （0.93, 2.03）- fold, respectively, after been induced by tannic acid at concentrations of 0.01, 0.05, 0.10, 0.50, and 1.00 mg/mL for 48 h （72 h, 96 h）.