CROSS-CORRELATION EFFECTS ON NMR LINESHAPES AND PEPTIDE CONFORMATION

Information about molecular structure and dynamics can potentially be obtained by studying dipole-dipole and chemical-shift anisotropy (CSA) auto-correlation and dipole-CSA cross-correlation effects in high-res olution NMR spectra, Equations for the lineshapes of the HN multiplet in the fragment-(NH)-N-15-CH- as a function of NH-CH dihedral angle ar e derived by including these effects within the framework of the Redfi eld treatment of relaxation, To test the utility of the theoretical re sults, H-1((15))N HSQC proton lineshape data for a variant of the enzy me staphylococcal nuclease in which all valine residues are labeled wi th N-15 have been analyzed to obtain the conformational angle (phi) be tween the N-H and adjacent C-H bonds, The results are generally in goo d agreement with values of phi obtained from crystal structure data. C onsiderations in the further development of the analysis of the linesh ape of the HN multiplet for experimental determinations of phi are dis cussed. (C) 1996 Academic Press, Inc.