EPR and DFT analysis of biologically relevant chromium(V) complexes with d-glucitol and d-glucose

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 freq...

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Bibliographic Details
Published in:Journal of inorganic biochemistry 2016-09, Vol.162, p.216-226
Main Authors: Van Doorslaer, Sabine, Beirinckx, Quinten, Nys, Kevin, Mangiameli, María Florencia, Cuypers, Bert, Callens, Freddy, Vrielinck, Henk, González, Juan Carlos
Format: Article
Language:English
Subjects:
1,2-diolato ligands
Chelating Agents - chemistry
Chromium - chemistry
DFT
Electron Spin Resonance Spectroscopy
ENDOR
EPR
Glucose - chemistry
Glutathione - chemistry
HYSCORE
Ligands
Oxidation-Reduction
Oxidochromium(V)
Potassium Dichromate - chemistry
Quantum Theory
Solutions
Sorbitol - chemistry
Temperature
Thermodynamics
Water - chemistry
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Summary: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. A combination of pulsed and high-field electron paramagnetic resonance and density functional theory reveals new information about the oxidochromium(V) complexes formed during reduction of Cr(V) in the presence of d-glucose or d-glucitol. [Display omitted] •Density functional theory and electron spin resonance help unravel Cr(V) chemistry.•Early stabilization of Cr(V) in d-glucitol involves H2O ligation rather than sugar.•Freezing influences counterion position in Cr(V) complexes of d-glucitol.•Reduction of Cr(VI) in presence of d-glucose leads to three Cr(V) species.•Cr(V) has a preference for binding of α-pyranose over β-pyranose.
ISSN:0162-0134
1873-3344
DOI:10.1016/j.jinorgbio.2016.07.012