title: Interactions of Cu(I) with selenium-containing amino acids determined by NMR, XAS, and DFT studies.
abstract: Cu(I) coordination by organoselenium compounds was recently reported as a mechanism for their prevention of copper-mediated DNA damage. To establish whether direct Se-Cu coordination may be involved in selenium antioxidant activity, Cu(I) coordination of the selenoamino acids methyl-Se-cysteine (MeSeCys) and selenomethionine (SeMet) was investigated. NMR results in D(2)O indicate that Cu(I) binds to the Se atom of both MeSeCys and SeMet as well as the carboxylic acid oxygen atom(s) or amine nitrogen atoms. X-ray absorption spectroscopy (XAS) and density functional theory (DFT) results confirm Se-Cu coordination, with the identification of a 2.4 Å Se-Cu vector in both the Se- and Cu-EXAFS data. XAS studies also show Cu(I) in an unusual three-coordinate environment with the additional two ligands arising from O/N (2.0 Å). DFT models of 1:1 Cu-selenoamino acid complexes suggest that both selenoamino acids coordinate Cu(I) through the selenium and amino groups, with the third ligand assumed to be water. These compounds represent the first structurally characterized copper(I) complexes with sulfur- or selenium-containing amino acids.
authors: Department of Chemistry, Clemson University, Clemson, South Carolina 29634-0973, USA.
authors: Hsiao C
authors: HC
authors: Wang
authors: Mindy
authors: M
authors: Riahi
authors: Joshua
authors: J
authors: Pothen
authors: Craig A
authors: CA
authors: Bayse
authors: Pamela
authors: P
authors: Riggs-Gelasco
authors: Julia L
authors: JL
authors: Brumaghim
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis* / Q000494:pharmacology; D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000494:pharmacology; D003300:Copper / Q000009:adverse effects / Q000737:chemistry*; D004249:DNA Damage / Q000187:drug effects; D009682:Magnetic Resonance Spectroscopy; D009584:Nitrogen / Q000737:chemistry; D016566:Organoselenium Compounds / Q000138:chemical synthesis* / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010100:Oxygen / Q000737:chemistry; D011789:Quantum Theory; D012643:Selenium / Q000737:chemistry*; D017279:Selenocysteine / Q000737:chemistry; D012645:Selenomethionine / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry; D014867:Water / Q000737:chemistry; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000975:Antioxidants; D056831:Coordination Complexes; D016566:Organoselenium Compounds; D014867:Water; D017279:Selenocysteine; D013455:Sulfur; D003300:Copper; D012645:Selenomethionine; D012643:Selenium; D009584:Nitrogen; D010100:Oxygen