title: Calcium-dependent conformational transition of calmodulin determined by Fourier transform infrared spectroscopy.
abstract: The Ca(2+)-induced conformational changes in calmodulin (CaM) were monitored by Fourier transform infrared spectroscopy (FT-IR) at different molar ratios of Ca(2+) to CaM. The results show that these changes occur in two distinctive transitions. The first transition involves significant changes in the overall secondary structure with a small gain in solvent accessibility, and is completed after the second Ca(2+) binds to both EF-hands of its C-terminal domain. The second transition is accompanied by CaM folding into a tighter, less hydrogen-exchangeable structure, and is completed by the addition of the fourth Ca(2+) to have four Ca(2+) per molecule. Particularly, α-helices in CaM-nCa(2+)(n=0, 1, 2) are less stable than those in CaM-nCa(2+)(n=3, 4).
authors: Department of Chemistry, Fudan University, Shanghai 200433, China.
authors: Ting
authors: T
authors: Yu
authors: Guangrong
authors: G
authors: Wu
authors: Huayan
authors: H
authors: Yang
authors: Jimin
authors: J
authors: Wang
authors: Shaoning
authors: S
authors: Yu
mesh_terms: D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000737:chemistry*; D041961:Deuterium Exchange Measurement; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D002147:Calmodulin; D002118:Calcium