The MD simulations demonstrate that the principal motion is a hinge motion between the N-terminal domain of troponin C and the ITC arm. We investigated whether phosphorylation and mutation affected the hinge dynamics (Figure and Table ). In wild type, the mean hinge angle increases on phosphorylation from 121.6° to 123.3° whereas in the presence of the G159D mutation, the mean angle decreases from 121.5° to 116.2°.