Integration of spin-state-selective excitation into 2D NMR correlation experiments with the heteronuclear ZQ/2Q pi rotations for 1JXH- resolved E.COSY-type measurements of heteronuclear coupling constants in proteins.

Abstract

Spin-State-Selective Excitation (S3E), which forexample selectively excites amide proton resonances corresponding toexclusively either the α or the β spin state of the covalentlybound 15N atom is employed for E.COSY-type extraction ofheteronuclear J coupling constants. Instead of having one spectrum with twopeaks (corresponding to the α or β spin state of15N), S3E generates two spectra, each with onlyone peak for each 15N nucleus. These two spectra are generatedfrom the same data set, so that there is no reduction in sensitivitycompared to conventional 1JNH-resolved methods.Another interesting feature in comparison with conventional methods is that1JNH can be suppressed during the evolutionperiod, meaning that no heteronuclear multiplet structure is visible in theω1 frequency dimension. The S3E pulsesequence element is combined with NOESY for measurement of3JN-Hβ and JN-Hαcoupling constants in either a hetero- or a homonuclear correlated version.Experimental confirmation is obtained using the protein RAP 17-;97(N-terminal domain of α2-macroglobulin ReceptorAssociated Protein).