title: Calcium-induced calmodulin conformational change. Electrochemical evaluation.
abstract: Calmodulin (CaM) is an essential protein present in all eukaryote cells, ranging from vertebrates to unicellular organisms. CaM is the most important Ca2+signalling protein, composed of two domains, N- and C-terminal domains, linked by a flexible central α-helix, and is responsible for the regulation of numerous calcium-mediated signalling pathways. Four calcium ions bind to CaM, changing its conformation and determining how it recognizes and regulates its cellular targets. The oxidation mechanism of native and denatured CaM, at a glassy carbon electrode, was investigated using differential pulse voltammetry and electrochemical impedance spectroscopy. Native and denatured CaM presented only one oxidation peak, related to the tyrosine amino acid residue oxidation. Calcium-induced calmodulin conformational change and the influence of Ca2+concentration on the electrochemical behaviour of CaM were evaluated, and significant differences, in the tyrosine amino acid residue peak potential and current, in the absence and in the presence of calcium ions, were observed. Gravimetric measurements were performed with a graphite coated piezoelectric quartz crystal with adsorbed CaM, and calcium aggregation by CaM was demonstrated.
authors: Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal.
authors: Isabel P G
authors: IP
authors: Fernandes
authors: Department of Chemistry, Faculty of Sciences and Technology, University of Coimbra, 3004-535 Coimbra, Portugal. Electronic address: brett@ci.uc.pt.
authors: Ana Maria
authors: AM
authors: Oliveira-Brett
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000737:chemistry* / Q000378:metabolism; D002244:Carbon / Q000737:chemistry; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D010084:Oxidation-Reduction; D011489:Protein Denaturation / Q000187:drug effects; D020836:Protein Structure, Quaternary / Q000187:drug effects; D013997:Time Factors
chemical_list: D002147:Calmodulin; D002244:Carbon; D002118:Calcium
keywords: Calcium; Calcium signalling protein; Calmodulin; Denaturing agents; Differential pulse voltammetry; Glassy carbon electrode