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 resonances exhibits a conformational dependence comparable to that of the corresponding (1)J(HC) scalar coupling in both magnitude (similar to 11 Hz at 14.1 T) and dihedral angle dependence. The similarity in the conformational dependence of the (1)J(HC) and deuterium isotope shift values suggests a common physical basis. Given the known distribution of (phi,psi) main-chain dihedral angles for glycine residues, the deuterium isotope shifts and the (1)J(HC) scalar couplings can determine conformations in the left- and right-handed helical-to-bridge regions of the (phi,psi) plane to an accuracy of approximately 13 degrees. In the absence of stereochemical assignments, the differential deuterium isotope shifts and the (1)J(HC) scalar couplings can be combined with limited independent structural information (e.g., the sign of phi) to determine the chirality of the deuterium substitution.