Spin-state-selective TPPI: A new method for suppression of heteronuclear coupling constants in multidimensional NMR experiments

A novel multidimensional NMR pulse sequence tool, spin-state-selective time -proportional phase incrementation (S-3 TPPI), is introduced. It amounts to application of different TPPIs on the two components of doublets so that t heir frequencies can be manipulated independently, The chief application is for suppression of large heteronuclear one-bond coupling constants in indi rect dimensions of multidimensional experiments without interchanging the t wo transverse magnetization components of doublets as conventional decoupli ng does, which is advantageous when they relax at different rates such as b y partial compensation of dipolar and CSA relaxation contributions. For exp erimental confirmation we use a sample of N-15-labeled neural cell adhesion molecule modules 1 and 2, a protein with a molecular weight of about 20 kD a, The new tool is general and can be combined with many multidimensional N MR experiments for proteins. (C) 1999 Academic Press.