Molecules with anisotropic magnetic susceptibilities are slightly aligned in solution when placed in a strong magnetic field. The degree of alignment can be determined by measuring the splittings in the high resolution NMR spectrum resulting from anisotropic nuclear interactions, such as electric quadrupole splittings or magnetic dipole splittings. The magnetic susceptibility tensor of the molecules can then be deduced from the degree of alignment. We propose to measure the susceptibility tensors for a variety of molecules containing atomic groupings occurring in peptides and proteins, and to compile a set of group tensors which can be added to predict the susceptibility tensor for any peptide in a given conformation. The set will be tested against peptides of known conformation and will then be applied to test the correctness of hypothesized structures for peptides or proteins of uncertain conformation.
