In addition, we have correlated the changes calculated by molecular dynamics with the measured effects of phosphorylation and mutation as a mechanism for direct comparison with experiment. Energetics calculations indicate that phosphorylation strengthens the switch peptide-NcTnC interaction in the wild type. In addition, phosphorylation changes the TnC helix A/B angle and hinge angle distribution and restricts their range of motion. In contrast, simulation of the cTnC G159D mutation indicated that the dynamics were different from wild type when unphosphorylated and that they often changed in the opposite direction on phosphorylation, consistent with the known ability of the mutation to modulate Ca 2+ -sensitivity and block its phosphorylation-dependent change.