title: Interaction of arsenite with a zinc finger CCHC peptide: evidence for formation of an As-Zn-peptide mixed complex.
abstract: The interaction of arsenite with a Cys(3)His (CCHC) zinc finger model (34-51) HIV-1 nucleocapsid protein p7 (NCp7) peptide in the absence and presence of Zn(II) was studied using fluorescence spectroscopy, CD (circular dichroism) and ESI-MS (Electrospray Ionization Mass Spectrometry). We found that arsenic forms different complexes with the free peptide and the zinc finger peptide. In the former case the peptide conformation differed greatly from that of the zinc finger, whereas in the second case a mixed As-Zn-peptide complex was formed with partial preservation of zinc finger conformation. An apparent stability constant was estimated for the mixed As-Zn-peptide complex (K=2083 M(-1) and 442 M(-1) at 25°C and pHs 6 and 7, respectively). Our study also shows that the interaction of arsenic with the CCHC motif is facilitated by glutathione (GSH), through formation of a GS-As-peptide conjugate.
authors.affiliation: Departamento de Química, Instituto de Ciências Exatas, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Pampulha, Belo Horizonte, MG, Brazil. demichel@netuno.lcc.ufmg.br
authors.forename: Cynthia
authors.initials: C
authors.lastname: Demicheli
authors.forename: Frédéric
authors.initials: F
authors.lastname: Frézard
authors.forename: Fernanda A
authors.initials: FA
authors.lastname: Pereira
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Santos
authors.forename: John B
authors.initials: JB
authors.lastname: Mangrum
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Farrell
mesh_terms: D000595:Amino Acid Sequence; D001151:Arsenic; D018053:Arsenites / Q000737:chemistry*; D002942:Circular Dichroism; D056831:Coordination Complexes / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry*; D011485:Protein Binding; D013050:Spectrometry, Fluorescence; D021241:Spectrometry, Mass, Electrospray Ionization; D015032:Zinc; D016335:Zinc Fingers; D054301:gag Gene Products, Human Immunodeficiency Virus / Q000737:chemistry*
chemical_list: D018053:Arsenites; D056831:Coordination Complexes; C071884:NCP7 protein, Human immunodeficiency virus 1; D010446:Peptide Fragments; D054301:gag Gene Products, Human Immunodeficiency Virus; D005978:Glutathione; D015032:Zinc; C015001:arsenite; D001151:Arsenic