Calcium-binding proteins afford calibration of dihedral-angle dependence of 3JNCγ coupling constant in aspartate and asparagine residues

Calibration of the 3JNCγ couplings across the N-Cα-Cβ-Cγ fragment of aspartate and asparagine residues is afforded by two interactions that produce fixed conformations of the side chains in solution. One is the binding of these side chains to calcium ions; the other is the H-bond interaction of these side chains with a backbone amide.