Fig. 5.

Screening of a small chemical library. Enzyme activity, in the presence and the absence of compound, was quantitated as the initial slope of the fluorescence emission as a function of time. Control wells (red squares) contained enzyme and substrate in the presence of an identical concentration of DMSO as that in the wells with compounds (black squares). Hits were selected as those compounds lowering the activity below a certain threshold (average activity of controls minus twice the standard deviation of those controls, lower dotted line). The blue square corresponds to quercetin.