title: Infrared study of synthetic peptide analogues of the calcium-binding site III of troponin C: The role of helix F of an EF-hand motif.
abstract: The EF-hand motif (helix-loop-helix) is a Ca(2+)-binding domain that is common among many intracellular Ca(2+)-binding proteins. We applied Fourier-transform infrared spectroscopy to study the synthetic peptide analogues of site III of rabbit skeletal muscle troponin C (helix E-loop-helix F). The 17-residue peptides corresponding to loop-helix F (DRDADGYIDAEELAEIF), where one residue is substituted by the D-type amino acid, were investigated to disturb the α-helical conformation of helix F systematically. These D-type-substituted peptides showed no band at about 1555 cm(-1) even in the Ca(2+)-loaded state although the native peptide (L-type only) showed a band at about 1555 cm(-1) in the Ca(2+)-loaded state, which is assigned to the side-chain COO(-) group of Glu at the 12th position, serving as the ligand for Ca(2+) in the bidentate coordination mode. Therefore, helix F is vital to the interaction between the Ca(2+) and the side-chain COO(-) group of Glu at the 12th position. Implications of the COO(-) antisymmetric stretch and the amide-I' of the synthetic peptide analogues of the Ca(2+)-binding sites are discussed.
authors: Department of Chemistry, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, Chiba 272-0827, Japan. nara.las@tmd.ac.jp.
authors: Masayuki
authors: M
authors: Nara
authors: Hisayuki
authors: H
authors: Morii
authors: Masaru
authors: M
authors: Tanokura
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D020832:EF Hand Motifs; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018656:Muscle Fibers, Fast-Twitch / Q000378:metabolism; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D019209:Troponin C / Q000737:chemistry* / Q000378:metabolism
chemical_list: D010455:Peptides; D019209:Troponin C; D002118:Calcium