Fourier transform infrared spectroscopic study on the Ca2+-bound coordination structures of synthetic peptide analogues of the calcium-binding site III of troponin C

✍ Scribed by Masayuki Nara; Hisayuki Morii; Fumiaki Yumoto; Hiroyuki Kagi; Masaru Tanokura

• Publisher: Wiley (John Wiley & Sons)
• Year: 2006
• Tongue: English
• Weight: 245 KB
• Volume: 82
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.20477

✦ Synopsis

Abstract

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. © 2006 Wiley Periodicals, Inc. Biopolymers 82: 339–343, 2006

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