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Updated: Jul 7, 2026
12:59
A Study of the Complexation of Mercury(II) with Dicysteinyl Tetrapeptides by Electrospray Ionization Mass Spectrometry
Published on: January 8, 2016
Mercury(II) complex formation with glutathione in alkaline aqueous solution
Vicky Mah1, Farideh Jalilehvand
1University of Calgary, 2500 University Dr. N. W., Calgary, AB T2N 1N4, Canada.
Summary
This study reveals how mercury(II) ions interact with glutathione (GSH), forming complexes like [Hg(GS)2](4-) and [Hg(GS)3](7-). Temperature and glutathione concentration significantly influence the speciation of these mercury-glutathione complexes.
Area of Science:
- Coordination Chemistry
- Biochemistry
- Spectroscopy
Background:
- Mercury(II) is a toxic heavy metal that can bind to biological molecules.
- Glutathione (GSH) is a crucial endogenous tripeptide antioxidant involved in metal detoxification.
- Understanding mercury-glutathione complexation is vital for toxicology and environmental science.
Purpose of the Study:
- To elucidate the structure and speciation of mercury(II)-glutathione complexes in alkaline aqueous solutions.
- To investigate the influence of temperature and glutathione concentration on complex formation.
- To compare mercury(II) complexation with glutathione versus cysteine.
Main Methods:
- Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy to determine structural parameters like Hg-S bond distances and coordination numbers.
- 199Hg Nuclear Magnetic Resonance (NMR) spectroscopy for speciation analysis.
- Analysis of alkaline aqueous solutions and frozen glycerol/water glasses at different temperatures.
Main Results:
- Dominant complexes identified as [Hg(GS)2](4-) and [Hg(GS)3](7-) with distinct Hg-S bond distances and coordination.
- [Hg(GS)4](10-) complex observed in minor amounts (<30%) at high glutathione excess.
- Higher coordination complexes ([Hg(GS)3](7-) and [Hg(GS)4](10-)) are favored at lower temperatures and moderate glutathione excess.
- Mercury(II)-cysteine complexation shows a reduced tendency for higher complexes due to stable chelate formation.
Conclusions:
- The speciation of mercury(II)-glutathione complexes is highly dependent on glutathione concentration and temperature.
- Stepwise exothermic bond formation drives the preference for higher coordination complexes at lower temperatures.
- Glycerol addition does not significantly alter mercury(II)-glutathione speciation in aqueous solutions.
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