Abstract
The effect of a series of protic ionic liquids on the catalytic activity of histidase (EC 4.3.1.3) using an enzymatic assay that monitored the growth of the trans-urocanic acid peak at 277 nm was studied. Results of the inhibition experiments indicated the that the ionic liquids with chaotropic bis(trifluoromethane)sulfonimide anion [NTf2−] had a significant stabilizing effect on the catalytic activity, which is reverse of the Hofmeister series.