General method for suppression of diagonal peaks in heteronuclear-edited NOESY spectroscopy.

A novel approach is proposed for suppression of diagonal peaks in 15N- and 13C-edited NOESY spectroscopy based on subtracting a spectrum with only diagonal peaks from the conventional NOESY spectrum. This method can be applied to most heteronuclear-edited NOESY experiments. It is far more sensitive than the TROSY-based approach for biomolecules with little TROSY effect, and nearly complete suppression of diagonal peaks can be achieved. The method has been demonstrated on samples of 15N-labeled calmodulin (17 kDa), 13C-labeled DdCAD-1 (24 kDa), and 13C-labeled hemoglobin (65 kDa), showing that cross-peaks very close to diagonals can be assigned reliably based on the difference spectra.