INFLUENCE OF CROSS-CORRELATION BETWEEN DIPOLAR AND CHEMICAL-SHIFT ANISOTROPY RELAXATION MECHANISMS UPON THE TRANSVERSE RELAXATION RATES OF N-15 IN MACROMOLECULES

Heteronuclear multiple-quantum coherence relaxation rates are calculated for the individual transitions of the, S spin in an AIS nuclear spin system assuming that the heteronucleus (S spin) has relaxation contributions from both intramolecular dipole-dipole and chemical shift anisotropy relaxation. The individual multiplet components of the heteronuclear zero- and double-quantum coherences are shown to have different transverse relaxation rates. The Cross-correlation between the two relaxation mechanisms is shown to be the dominant cause of the calculated differential line broadening. Experimental data are presented using as an example a uniformly N-15 labelled sample of human epidermal growth factor.