Molecular dynamics simulations revealed Ca2+-dependent conformational change of Calmodulin

Molecular dynamics simulations were performed to simulate Ca²⁺-dependent conformational change of calmodulin (CaM). Simulations of the fully Ca²⁺-bound form of CaM (Holo-CaM) and the Ca²⁺-free form (Apo-CaM) were performed in solution for 4 ns starting from the X-ray crystal structure of Holo-CaM. A striking difference was observed between the trajectories of Holo-CaM and Apo-CaM: the central helix remained straight in the former but became largely bent in the latter. Also, the flexibility of Apo-CaM was higher than that of Holo-CaM. The results indicated that the bound Ca²⁺ ions harden the structure of CaM. [Copyright &y& Elsevier]