title: Analytical determination of apparent stability constants using a copper ion selective electrode.
abstract: Copper(II) complexes of di-, tri- and tetra peptides with previously published protonation constants were re-investigated using pH and copper ion selective electrode (ISE) potentiometry in conjunction with a modified version of HYPERQUAD computer program. The purpose was to demonstrate the suitability of the ISE approach for the determination of apparent stability constants for copper(II) complexes with ligands for which proton stability constants were not available. The interactions of Cu(2+) with oligopeptides were also analysed using surface enhanced laser desorption/ionisation time-of-flight mass spectrometry (SELDI-ToF-MS). The results provide an insight into the metal complex species formed, their apparent stabilities under selected conditions and the effect of the relative positions of certain amino acids within the peptide sequence.
authors.affiliation: Alltech Bioscience Centre, Sarney, Dunboyne, Co. Meath, Ireland. lbyrne@alltech.com
authors.forename: L A
authors.initials: LA
authors.lastname: Byrne
authors.forename: M J
authors.initials: MJ
authors.lastname: Hynes
authors.forename: C D
authors.initials: CD
authors.lastname: Connolly
authors.forename: R A
authors.initials: RA
authors.lastname: Murphy
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D004563:Electrochemistry; D004566:Electrodes; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D009842:Oligopeptides / Q000737:chemistry*; D011199:Potentiometry / Q000379:methods; D011485:Protein Binding; D055550:Protein Stability; D012984:Software; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D056831:Coordination Complexes; D009842:Oligopeptides; D003300:Copper