Rapid estimation of relative amide proton exchange rates of N-15-labelled proteins by a straightforward water selective NOESY-HSQC experiment

A straightforward heteronuclear pseudo-3D NOESY-HSQC pulse sequence using radiation damping to selectively invert magnetization at the water frequency was developed to estimate the amide proton exchange rates in N-15-labelled proteins. The peak intensities in the resultant 2D spectrum allow a direct classification of amide proton exchange rates according 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 obtained.