title: Determination of the solution structure of a synthetic two-site calcium-binding homodimeric protein domain by NMR spectroscopy.
abstract: The solution structure of a 34-residue synthetic calcium-binding peptide from site III of chicken troponin-C has been determined by 1H NMR spectroscopy. In solution and in the presence of calcium this peptide forms a symmetric two-site homodimeric calcium-binding domain (Shaw et al., 1990). The solution structure of this dimer was determined from the measurement of 470 NOEs from a 75-ms NOESY data set. For the dimer structure determination, the constraint list included 868 distance restraints, 44 phi angles, and 24 chi 1 and 2 chi 2 angles. Seven structures were calculated by restrained molecular dynamics using a procedure in which intramonomer distances were used first and then all distances, intra- and intermonomer, were input during further dynamics. The structures exhibited a fold very similar to the C-terminal domain of troponin-C comprised of a pair of helix-loop-helix calcium-binding sites. The rms deviation of these structures for backbone atoms between residues 97-122 and 97'-122' for the dimer was 0.82 A. The dimer structure was also calculated to be more symmetric than sites III and IV in troponin-C.
authors.affiliation: Department of Biochemistry, University of Alberta, Edmonton, Canada.
authors.forename: G S
authors.initials: GS
authors.lastname: Shaw
authors.forename: R S
authors.initials: RS
authors.lastname: Hodges
authors.forename: B D
authors.initials: BD
authors.lastname: Sykes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000138:chemical synthesis / Q000737:chemistry*; D002645:Chickens; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D012996:Solutions; D014336:Troponin / Q000737:chemistry; D019209:Troponin C
chemical_list: D002135:Calcium-Binding Proteins; D010446:Peptide Fragments; D012996:Solutions; D014336:Troponin; D019209:Troponin C