title: Coordination abilities of N-terminal fragments of alpha-synuclein towards copper(II) ions: a combined potentiometric and spectroscopic study.
abstract: Copper(II) complexes of the 1-17 (MDVFMKGLSKAKEGVVA-NH(2)), 1-28 (MDVFMKGLSKAKEGVVAAAEKTKQGVAE-NH(2)), 1-39 (MDVFMKGLSKAKEGVVAAAEKTKQGVAEAPGKTKEGVLY-NH(2)) and 1-39 (A30P) fragments of alpha-synuclein were studied by potentiometric, UV-Vis (UV-visible), CD (circular dichroism) and EPR (electron paramagnetic resonance) spectroscopic methods to determine the stoichiometry, stability constants and coordination modes of the complexes formed. The beta-carboxylate group of Asp residue in second position of the peptide chain coordinates strongly to Cu(II) ion over the pH range 4-9.5 to give unusually stable 2N complex with {NH(2), N(-), beta-COO(-), H(2)O} coordination mode. At pH above 7 the results suggest the formation of 2N, 3N, 4N complexes (in equatorial plane) and the involvement of the lateral NH(2) group of Lys residue in the axial coordination of Cu(II) ion. In CD spectra sigma (epsilon-NH(2)-Lys)-->Cu(II) charge transfer transition is observed. Addition of the 18-28 and 18-39 fragments to the 1-17 peptide does not change the coordination mode and the 1-39 fragment forms the Cu(II) complexes with higher stabilities compared to those of the 1-17, 1-28 and 1-39(A30P) fragments of alpha-synuclein.
authors.affiliation: Faculty of Chemistry, University of Wrocław, Joliot-Curie 14, 50-383 Wrocław, Poland. terkow@wchuwr.chem.uni.wroc.pl
authors.forename: Teresa
authors.initials: T
authors.lastname: Kowalik-Jankowska
authors.forename: Anna
authors.initials: A
authors.lastname: Rajewska
authors.forename: Kornelia
authors.initials: K
authors.lastname: Wiśniewska
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Grzonka
authors.forename: Julia
authors.initials: J
authors.lastname: Jezierska
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites / Q000235:genetics; D002942:Circular Dichroism; D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D004355:Drug Stability; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011199:Potentiometry; D013053:Spectrophotometry; D051844:alpha-Synuclein / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010446:Peptide Fragments; D051844:alpha-Synuclein; D003300:Copper