Infrared spectroscopic study of the metal-coordination structures of calcium-binding proteins.
Carboxylate (COO(-)) groups can coordinate to metal ions in of the following four modes: 'unidentate', 'bidentate', 'bridging' and 'pseudo-bridging' modes. COO(-) stretching frequencies provide information about the coordination modes of COO(-) groups to metal ions. We review the Fourier-transform infrared spectroscopy (FTIR) of side-chain COO(-) groups of Ca(2+)-binding proteins: pike parvalbumin pI 4.10, bovine calmodulin and Akazara scallop troponin C. FTIR spectroscopy of Akazara scallop troponin C has demonstrated that the coordination structure of Mg(2+) is distinctly different from that of Ca(2+) in the Ca(2+)-binding site. The assignments of the COO(-) antisymmetric stretch have been ensured on the basis of the spectra of calcium-binding peptide analogues. The downshift of the COO(-) antisymmetric stretching mode from 1565 cm(-1) to 1555-1540 cm(-1) upon Ca(2+) binding is a commonly observed feature of FTIR spectra for EF-hand proteins.
Nara
Masayuki
M
Laboratory of Chemistry, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Chiba 272-0827, Japan.
Tanokura
Masaru
M
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D006801:Humans; D008670:Metals / Q000737:chemistry*; D011485:Protein Binding; D013055:Spectrophotometry, Infrared / Q000379:methods*
D002135:Calcium-Binding Proteins; D008670:Metals; D002118:Calcium