NMR chemical shifts and structure refinement in proteins

Summary Computation of the ¹³C chemical shifts (or shieldings) of glycine, alanine and valine residues in bovine and Drosophila calmodulins and Staphylococcal nuclease, and comparison with experimental values, is reported using a gauge-including atomic orbital quantum-chemical approach. The full 24 ppm shielding range is reproduced (overall r.m.s.d.=1.4 ppm) using optimized protein structures, corrected for bond-length/bond-angle errors, and rovibrational effects.To whom correspondence should be addressed.