A NEW LINEAR PREDICTION MODEL METHOD FOR THE DETERMINATION OF SLOW AMIDE PROTON-EXCHANGE RATES FROM A SERIES OF ONE-DIMENSIONAL H-1-NMR SPECTRA

A NMR method for quantitative determination of the exchange rates of slowly exchanging amide protons in proteins is presented, with the des-[Phe(B25)] mutant of human insulin as an example. The exchange rates are obtained by fitting a model that includes exponential decay to the parameters produced by a linear prediction analysis of a series of one-dimensional free induction decays recorded during the exchange of the amide protons with solvent deuterium. Because the linear prediction model method is able to combine in formation from independent linear prediction calculations and to exploit differences in chemical shift and exchange rate simultaneously, it allows exchange rates of amide protons with closely spaced signals to be determined. The method covers exchange rates from 0.1 h-1 to well above 10 h-1.