Proton chemical shifts in fluorocinnamate-chymotrypsin complexes.

Binding of cinnamate or fluorocinnamate anions to alpha-chymotrypsin is accompanied by chemical shift changes at each proton of the cinnamate structure. The direction and magnitude of these shifts are consistent with the expected binding of these inhibitors at the active site of the enzyme. The protein-induced fluorine chemical shift effects at each position in the aromatic ring are compared to the shift effects observed when a hydrogen occupies the same position. There is no discernible relation between the proton and fluorine chemical shifts, leading to the conclusion that those factors dominantly responsible for the shift effects are different for the two sets of data.