title: Studies on the peptide corresponding to residues 34-47 of bovine factor X.
abstract: Calcium binding studies of a 14-residue peptide corresponding to the 37-46 sequence of bovine factor X were performed using calcium ion selective electrode titrations and equilibrium dialysis. The presence of gamma-carboxyglutamic acid residues at positions 36 and 40 coupled with the assumption that the peptide would bind calcium ions also prompted an investigation of possibly secondary conformational changes in the peptide by use of circular dichroism spectroscopy. Equilibrium dialysis revealed a single relatively weak calcium binding site (log Ka = 2.39); an ion selective electrode experiment confirmed this result (log Ka = 2.17). The peptide maintained a random coil conformation throughout the calcium ion titrations as measured by circular dichroism.
authors.affiliation: Department of Chemistry, University of North Carolina at Chapel Hill, USA.
authors.forename: A D
authors.initials: AD
authors.lastname: King
authors.forename: N W
authors.initials: NW
authors.lastname: Huh
authors.forename: L G
authors.initials: LG
authors.lastname: Pedersen
authors.forename: R G
authors.initials: RG
authors.lastname: Hiskey
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002417:Cattle; D002942:Circular Dichroism; D003956:Dialysis; D004566:Electrodes; D005170:Factor X / Q000737:chemistry*; D008968:Molecular Conformation; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments; D005170:Factor X; D002118:Calcium