Fig. 4. TA and DOP showed no effect on QseC kinase activity. The QseC enriched membrane and QseB isolated from E. coli BL21 were used for in vitro kinase activity assay in the presence EPI together with TAs, DOP and PTL. After 30 min of incubation at room temperature, the kinase activity was determined by measuring the remaining ATP in the reaction and it showed that the addition of EPI increased the kinase activity of QseBC significantly. The addition of TAs and DOP did not show significant effect while PTL showed significant inhibition of kinase activity. (For all graphs, each data point is the mean value ± SEM (n = 3), *p<0.05; **p<0.01; ***p<0.001. Student t test was used for statistical calculations.