CLEAN TOCSY FOR H-1 SPIN SYSTEM-IDENTIFICATION IN MACROMOLECULES

The authors introduce a technique that provides, for the first time, clean TOCSY spectra and suppresses contributions from cross relaxation based on the opposite signs of longitudinal and transverse cross-relaxation rates in large molecules. It is shown that the introduction of delays into an MLEV-17 pulse sequence allows the suppression of cross relaxation in TOCSY under practical, experimental conditions with nonideal pulses. With this modification the TOCSY experiment carries the promise to facilitate 1H spin system identifications in macromolecules and to enable such studies with bigger molecules than would be possible with presently available techniques.