SELECTIVE FLUORINE-PROTON NUCLEAR OVERHAUSER EFFECTS IN 4-TRIFLUOROMETHYLBENZENESULFONYL-ALPHA-CHYMOTRYPSIN

Selective, 19F{1H} nuclear Overhauser effects have been used to explore the nature of the protons which contribute to relaxation of the trifluoromethyl group in p-trifluoromethylbenzenesulfonvichymotrypsin. Spin diffusion is shown to play a role in decreasing the specificity of these effects, but its influence is not so strong as to completely obliterate structural information. The Overhauser effects were determined as a function of irradiation power level (γH2) and a structural model for the environment around the CF3 group in the modified enzyme was developed. The model is consistent with observed spin-lattice relaxation rates for the protons and fluorine nuclei in the system and the variation in the 19F{1H} Overhauser effects with the frequency and intensity of the irradiating field. © 1979, American Chemical Society. All rights reserved.