The role of coherence transfer efficiency in design of TROSY-type multidimensional NMR experiments

An improved method for TROSY-type (Pervushin ct al., Proc. Natl. Acad. Sci. USA 94, 12366-12371 (1997)) heteronuclear two-dimensional correlation invo lving protons of negligible CSA is presented. Rather than applying a simple INEPT sequence for back-transfer to protons (Pervushin et al., J. Am. Chem . Sec. 120, 6394-6400 (1998)), we replace the pi/2 proton pulse in INEPT by a spin-state-selective coherence transfer element (Sorensen et al., J. Bio mol. NMR 10, 181-186 (1997)) and maintain broadband decoupling during acqui sition. Theoretically that results in a sensitivity enhancement of a factor of 2. The new method is demonstrated using a C-13, (1)5N-labeled protein s ample, RAP 18-112 (N-terminal domain of alpha(2)-macroglobulin receptor ass ociated protein), at 750 MHz. (C) 1999 Academic Press.