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Solution structures of chromium(VI) complexes with glutathione and model thiols
1Centre for Heavy Metals Research and Centre for Structural Biology and Structural Chemistry, School of Chemistry, University of Sydney, Sydney, NSW 2006, Australia.
Inorganic Chemistry
|January 6, 2004
Summary
Chromium(VI) reacts with glutathione to form tetrahedral complexes. In aqueous solutions, these reversibly form five-coordinate species, impacting cellular damage and enzyme inhibition.
Area of Science:
- Inorganic Chemistry
- Biochemistry
- Toxicology
Background:
- Chromium(VI) is a genotoxic metal linked to cellular damage.
- Glutathione is a key biological reductant involved in cellular defense.
- Understanding Chromium(VI)-glutathione interactions is crucial for cellular metabolism and toxicity studies.
Purpose of the Study:
- To structurally characterize Chromium(VI) complexes with glutathione and model thiols.
- To investigate the reaction pathways and intermediates in aqueous and non-aqueous solutions.
- To clarify the role of these complexes in Chromium(VI) cellular metabolism and toxicity.
Main Methods:
- X-ray absorption fine structure (XAFS) and X-ray absorption near-edge structure (XANES) spectroscopies.
- Electrospray mass spectrometry (ESMS) and UV-vis spectroscopy.
- Kinetic studies and XAFS data modeling.
Main Results:
- Chromium(VI)-thiolato complexes were formed and characterized.
- Tetrahedral [CrO(3)(SR)](-) species were observed in solid state, aprotic solvents, and gas phase.
- Reversible addition of solvent molecules led to five-coordinate [CrO(3)(SR)L](-) species in aqueous/alcoholic solutions.
- No stable Cr(IV) intermediates were detected in acidic aqueous solutions.
- The formation of five-coordinate species is a novel observation for Chromium(VI) complexes.
Conclusions:
- Chromium(VI) forms tetrahedral and five-coordinate complexes with glutathione and thiols.
- The reversible solvent addition to Chromium(VI) complexes is a key finding.
- These interactions are critical for Chromium(VI) reactivity in biological systems, influencing DNA/protein damage and enzyme inhibition.