title: EPR and DFT analysis of biologically relevant chromium(V) complexes with d-glucitol and d-glucose.
abstract: 1,2-diolato ligands, such as carbohydrates and glycoproteins, tend to stabilize chromium(V), thus forming important intermediates that have been implicated in the genotoxicity of Cr(VI). Since many years, room-temperature continuous-wave electron paramagnetic resonance (EPR) at X-band microwave frequencies has been used as a standard characterization tool to study chromium(V) intermediates formed during the reduction of Cr(VI) in the presence of biomolecules. In this work, the added value is tested of using a combination of pulsed and high-field EPR techniques with density functional theory computations to unravel the nature of Cr(V) complexes with biologically relevant chelators, such as carbohydrates. The study focuses on the oxidochromium(V) complexes formed during reduction of potassium dichromate with glutathione in the presence of the monosaccharide d-glucose or the polyalcohol d-glucitol. It is shown that although the presence of a multitude of Cr(V) intermediates may hamper a complete structural determination, the combined EPR and DFT approach reveals unambiguously the effect of freezing on the location of the counterions, the gradual replacement of water ligands by the diols, and the preference of Cr(V) to bind certain conformers.
authors.affiliation: University of Antwerp, Department of Physics, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: sabine.vandoorslaer@uantwerpen.be.
authors.forename: Sabine
authors.initials: S
authors.lastname: Van Doorslaer
authors.affiliation: University of Antwerp, Department of Physics, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: quinten.beirinckx@student.uantwerpen.be.
authors.forename: Quinten
authors.initials: Q
authors.lastname: Beirinckx
authors.affiliation: University of Antwerp, Department of Physics, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: Kevin.nys@student.uantwerpen.be.
authors.forename: Kevin
authors.initials: K
authors.lastname: Nys
authors.affiliation: Universidad National de Rosario, Departamento de Químico Física - Área Química General, Facultad de Ciencias Bioquímicas y Farmacéuticas, IQUIR-CONICET, Suipacha 531, Rosario, Santa Fe, Argentina. Electronic address: mangiameli@iquir-conicet.gov.ar.
authors.forename: María Florencia
authors.initials: MF
authors.lastname: Mangiameli
authors.affiliation: University of Antwerp, Department of Physics, Universiteitsplein 1, B-2610 Antwerp, Belgium. Electronic address: bert.cuypers@uantwerpen.be.
authors.forename: Bert
authors.initials: B
authors.lastname: Cuypers
authors.affiliation: Ghent University, Dept. of Solid State Sciences, Krijgslaan 281-S1, B-9000 Ghent, Belgium. Electronic address: freddy.callens@ugent.be.
authors.forename: Freddy
authors.initials: F
authors.lastname: Callens
authors.affiliation: Ghent University, Dept. of Solid State Sciences, Krijgslaan 281-S1, B-9000 Ghent, Belgium. Electronic address: henk.vrielinck@ugent.be.
authors.forename: Henk
authors.initials: H
authors.lastname: Vrielinck
authors.affiliation: University of Antwerp, Department of Physics, Universiteitsplein 1, B-2610 Antwerp, Belgium; Universidad National de Rosario, Departamento de Químico Física - Área Química General, Facultad de Ciencias Bioquímicas y Farmacéuticas, IQUIR-CONICET, Suipacha 531, Rosario, Santa Fe, Argentina. Electronic address: gonzalez@iquir-conicet.gov.ar.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: González
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005947:Glucose / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry; D008024:Ligands; D010084:Oxidation-Reduction; D011192:Potassium Dichromate / Q000737:chemistry; D011789:Quantum Theory; D012996:Solutions; D013012:Sorbitol / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D002614:Chelating Agents; D008024:Ligands; D012996:Solutions; D014867:Water; D002857:Chromium; D013012:Sorbitol; D005978:Glutathione; D005947:Glucose; D011192:Potassium Dichromate
keywords: 1,2-diolato ligands; DFT; ENDOR; EPR; HYSCORE; Oxidochromium(V)