Improved photocontrol of alpha-chymotrypsin activity: peptidomimetic trifluoromethylketone photoswitch enzyme inhibitors.

A series of peptidomimetic trifluoromethylketones containing the photoisomerisable azobenzene group have been synthesised, photoisomerised and assayed against the serine protease alpha-chymotrypsin. All are inhibitors of the enzyme and exhibit up to a fivefold increase in activity on UV irradiation. Visible irradiation returns activity to close to that of the original sample. These results suggest the trifluoromethylketone group to be the best electrophilic enzyme binding group for use in photoswitch inhibitors of alpha-chymotrypsin.