MONITORING OF SLOW CONFORMATIONAL EXCHANGE BY DOUBLY SELECTIVE IRRADIATION IN NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY

A new NMR spectroscopic method is described that allows a selective de termination to be made of whether two sites are connected by a slow co nformational exchange process. An accompanying approximate theory is d erived which permits a quantitative estimate to be made of the exchang e rate in numerous situations. Numerical simulations are presented to specify the domain of validity of the theory. Experimental verificatio n is demonstrated for an aromatic ring in the bovine pancreatic trypsi n inhibitor protein.