DIFFERENTIAL DEUTERIUM-ISOTOPE SHIFTS AND ONE-BOND H-1-C-13 SCALAR COUPLINGS IN THE CONFORMATIONAL-ANALYSIS OF PROTEIN GLYCINE RESIDUES

The one-bond deuterium isotope shift effect for glycine C-alpha resona nces exhibits a conformational dependence comparable to that of the co rresponding (1)J(HC) scalar coupling in both magnitude (similar to 11 Hz at 14.1 T) and dihedral angle dependence. The similarity in the con formational dependence of the (1)J(HC) and deuterium isotope shift val ues suggests a common physical basis. Given the known distribution of (phi,psi) main-chain dihedral angles for glycine residues, the deuteri um isotope shifts and the (1)J(HC) scalar couplings can determine conf ormations in the left- and right-handed helical-to-bridge regions of t he (phi,psi) plane to an accuracy of approximately 13 degrees. In the absence of stereochemical assignments, the differential deuterium isot ope shifts and the (1)J(HC) scalar couplings can be combined with limi ted independent structural information (e.g., the sign of phi) to dete rmine the chirality of the deuterium substitution.