Structures and Electronic Properties of Calcium Binding Proteins with EF-hand Motif :Semiempirical Molecular Orbital Calculations

Abstract

Calcium ion (Ca) plays many essential roles as an intercellular messenger in the living body. The binding of Ca to the calcium binding protein (CaBP) is concerned with the mechanism of messenger passing. In the present study, we investigated the stable structures and their electronic properties for three types of CaBPs having EF-hand motif, using molecular simulations based on classic molecular mechanics and semiempirical molecular orbital methods. Furthermore, the effect of Ca binding to CaBP was investigated to elucidate the difference in Ca binding affinity between the CaBPs. The results clarified that the difference in Ca binding affinity of CaBPs is explained by the binding energies between CaBP and Ca.