Calcium-Binding Proteins, Overview
Metal ions play several major roles in the structures and functions of proteins. The bindings of some metal ions increase the stabilities of proteins or of protein domains. Some transition metal ions take part in catalysis in many enzymes. The oxygen, nitrogen, and sulfur atoms of several amino acid side chains, as well as the carbonyl oxygen of the peptide group and the carboxylate of the C-terminal residue may be involved in coordination of metal ions. Binding of the Ca2+ion is limited to not only oxygen-containing ligands, primarily the carboxylates of Asp (aspartic acid) and of Glu (glutamic acid), but also the oxygens of Asn (asparagine), Gln (glutamine), Ser (serine), Thr (threonine), Tyr (tyrosine), and of the main chain peptides. A...