Significantly the unphosphorylated G159D and WT phosphorylated are comparable at 12.6° and 12.3° respectively The interaction energy between regions of cTnC and cTnI have been evaluated using the MMPBSA methodology (Table ). Three regions of cTnI were chosen due to their structural and functional significance: the switch peptide (cTnI147-163) which is in close contact with the A/B angle (hydrophobic patch) region of NcTnC, cTnI34-71 which interacts with the C-terminal domain of cTnC and is close to the G159D mutation site, and finally the 'inhibitory peptide' (TnI131-147) which crosses from the NcTnC domain to the ITC domain and is hypothesised to be critical in the contraction/relaxation process.