Binding energies were calculated for EF hands from CaM and TnC, proteins with solved x-ray structures, and compared to the homology-modeled hBest1 and mutant hBest1 EF hands. Calculations were performed using implicit Poisson-Boltzmann hydration with and without an added explicit water ligand for bound Ca²⁺ as described in Materials and methods. EF1 or TnC is known not to bind Ca.