An improved J-multiplied method for the measurement of (3)J(H-N,H-alpha) from the two-dimensional N-15-H-1 correlation spectrum

An improved method utilizing J-multiplication for the measurement of (3)J(H -N, H-alpha) coupling constant is introduced. The current method benefits f rom slower relaxation rate of heteronuclear multiple-quantum coherence. Fur thermore, it combines incrementation periods for J-multiplication and N-15 chemical-shift evolution. This reduces the length of the overall pulse sequ ence by t(1). This, together with favourable relaxation properties of multi ple-quantum coherence, leads to narrower linewidths in the F-1 dimension re lative to the previously presented sensitivity-enhanced, J-multiplied HSQC experiment. The method is demonstrated on human ubiquitin. Copyright (C) 19 99 John Wiley & Sons, Ltd.