title: Metal complexes of taurine. The first reported solution equilibrium studies for complex formation by taurine at physiological pH; the copper(II)-glycylglycinate-taurine and the copper(II)-glycylaspartate-taurine systems.
abstract: The first solution studies at physiological pH for the formation of metal complexes of taurine, +NH3CH2CH2S03-, one of the most abundant low molecular weight organic compounds in the animal kingdom, are reported. The complexes Cu(Gly-GlyH-1) (1) and [Cu(Gly-AspH-1)] (2) react with taurine to give the ternary complexes [Cu(Gly-GlyH-1)taurine]- (3) (log K=2.95+/-0.03, I=0.2M, T=25.0 degrees C) and [Cu(Gly-AspH-1)taurine]2- (4) (log K=2.68+/-0.02) in which taurine acts as an N-donor ligand, most likely monodentate, without involvement of the sulphonate group in coordination. The results of the pH-metric studies are confirmed by visible and EPR spectrophotometric studies. The taurine complexes are less stable than the analogous complexes of beta-alanine due to the decreased basicity of the amino group in the former ligand, and in the case of the Cu(Gly-GlyH-1) complexes due to involvement of the carboxylate group of beta-alanine in axial coordination.
authors.affiliation: Department of Chemistry, Royal College of Surgeons in Ireland, Dublin.
authors.forename: E C
authors.initials: EC
authors.lastname: O'Brien
authors.forename: E
authors.initials: E
authors.lastname: Farkas
authors.forename: A
authors.initials: A
authors.lastname: Rockenbauer
authors.forename: K B
authors.initials: KB
authors.lastname: Nolan
mesh_terms: D000818:Animals; D003300:Copper / Q000737:chemistry*; D004151:Dipeptides / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005998:Glycine / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008024:Ligands; D009942:Organometallic Compounds / Q000737:chemistry*; D012984:Software; D013053:Spectrophotometry; D013654:Taurine / Q000737:chemistry* / Q000502:physiology
chemical_list: D004151:Dipeptides; D008024:Ligands; D009942:Organometallic Compounds; D013654:Taurine; C035650:glycylaspartic acid; C018493:cupric glycinate; D003300:Copper; D005998:Glycine