RAPID ESTIMATION OF RELATIVE AMIDE PROTON-EXCHANGE RATES OF N-15-LABELED PROTEINS BY A STRAIGHTFORWARD WATER SELECTIVE NOESY-HSQC EXPERIMENT

A straightforward heteronuclear pseudo-3D NOESY-HSQC pulse sequence us ing radiation damping to selectively invert magnetization at the water frequency was developed to estimate the amide proton exchange rates i n N-15-labelled proteins. The peak intensities in the resultant 2D spe ctrum allow a direct classification of amide proton exchange rates acc ording to short (ms), intermediate (ms to s) or long (greater than or equal to s) residence times. This method was successfully used for the analysis of amide proton exchange rates in the N-15-labelled FruR DNA -binding domain and pertinent information about its dynamics was obtai ned.