Strong Interaction of Bovine Brain Calmodulin with Bisphenol A: Effects on Secondary Structure, Conformation, Ca2+-Binding Affinity, Gibbs Energy, and Domain Cooperativity

摘要

Calmodulin (CaM) is a major member of the family of Ca2+-binding proteins. In this study, effects on Ca2+-bincling affinity and conformation of CaM by bisphenol A (BPA) were investigated by using circular dichroism and UV absorbance spectroscopy, domain-specific fluorescence spectroscopy, and isothermal titration calorimetry. It was revealed that the existence of a strongly perturbed chirality arose from four BPA molecules binding to CaM by hydrogen bonding, and that the conformation of CaM was modified for binding with BPA. Consequently, the interaction CaM with BPA elicits reduction of Ca2+-binding affinity and the deterioration of domain cooperativity.