Differential deuterium isotope shifts and one-bond 1H−13C scalar couplings in the conformational analysis of protein glycine residues

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