Spin-state-selective excitation. Application for E.COSY-type measurement of J(HH) coupling constants

A new pulse sequence element, spin-state-selective excitation ((SE)-E-3), is introduced and combined with E.COSY-type techniques for measurement of H-1-H-1 J coupling constants, (SE)-E-3 edits the two resonances of a doublet prior to an evolution period of a multidimensional experiment and results in a subspectrum for each resonance, Due to this editing the large heteronuclear one-bond coupling constants normally exploited for separation of submultiplets in E.COSY-type experiments can be suppressed in experiments employing (SE)-E-3. Hence there is a concomitant effective increase in resolution, Apart from pulse imperfections and relaxation during a delay (4J)(-1) (SE)-E-3 causes no loss of sensitivity in comparison to conventional experiments. Experimental confirmation is done using the protein RAP 17-97 (N-terminal domain of alpha(2)-macroglobulin receptor associated protein). (C) 1997 Academic Press.