OPTIMIZATION OF COSY AND RELATED METHODS - APPLICATION TO H-1-NMR OF HORSE FERRICYTOCHROME-C

The sensitivity of COSY is severely reduced when linewidths exceed coupling constants, and it is widely believed that magnitude COSY (MCOSY) will then give optimum signal-to-noise ratios. Analysis of the probability density function for the absolute value of random noise shows that this is not correct: a pure-phase dispersion-mode spectrum is generally superior, and a phase-sensitive experiment should be used even if the spectrum is to be plotted in absolute value. The analytical results are supported by a series of experiments used to assign the spin system of the axial methionine ligand in horse ferricytochrome c. © 1993 Academic Press. All rights reserved.