Fourier transform infrared spectroscopic study on the Ca2+ -bound coordination structures of synthetic peptide analogues of the calcium-binding site III of troponin C.
The coordination structures of Ca(2+) ion bound to synthetic peptide analogues of the calcium-binding site III of rabbit skeletal muscle troponin C (TnC) were investigated by Fourier transform infrared (FTIR) spectroscopy. The region of the COO(-) antisymmetric stretching vibration provides information about the coordination modes of a COO(-) group to a metal ion. The 34-residue peptide corresponding to the EF hand motif (helix-loop-helix) showed a band at 1552 cm(-1) in the Ca(2+)-loaded state, indicating that the side-chain COO(-) group of Glu at the 12th position serves as a ligand for Ca(2+) in the bidentate coordination mode. On the other hand, the 13-residue peptide (Ac-DRDADGYIDAEEL-NH(2)) containing the Ca(2+)-binding site III (DRDADGYIDAEE) did not show such spectral patterns in the Ca(2+)-loaded state, meaning that shorter synthetic peptide corresponding to the site III has less or no affinity for Ca(2+). It was found that the 17-residue peptide (Ac-DRDADGYIDAEELAEIF-NH(2)) is the minimum peptide necessary for the interaction of side-chain COO(-)of Glu at the 12th position with Ca(2+) in the bidentate coordination mode. We discuss the relationship between the amino acid length of synthetic peptide analogues and the formation of Ca(2+)-bound coordination structure.
Nara
Masayuki
M
Laboratory of Chemistry, College of Liberal Arts and Sciences, Tokyo Medical and Dental University, 2-8-30 Kohnodai, Ichikawa, Chiba 272-0827, Japan. nara.las@tmd.ac.jp
Morii
Hisayuki
H
Yumoto
Fumiaki
F
Kagi
Hiroyuki
H
Tanokura
Masaru
M
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry; D011485:Protein Binding; D011817:Rabbits; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D019209:Troponin C / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism
D010455:Peptides; D019209:Troponin C; D002118:Calcium