Formation of Mercury(II)-Glutathione Conjugates Examined Using High Mass Accuracy Mass Spectrometry


Maternal exposure to Hg(II) during pregnancy has been identified as a potential causal factor in the development of severe neurobehavioral disorders. Children with autism have been identified with lower reduced glutathione (GSH)/oxidized glutathione (GSSG) ratios, and GSH is known to strongly bind Hg(II). In order to gain insight into the mechanism by which GSH binds Hg(II), high resolution mass spectrometry coupled with tandem mass spectrometry was utilized to examine the conjugation process. While the 1:1 Hg(II):GSH conjugate is not formed immediately upon mixing aqueous solutions of Hg(II) and GSH, two species containing Hg(II) are observed:the 1:2 Hg(II):GSH conjugate, [(GS)2 Hg + H+], and a second Hg(II)-containing species around m/z 544. Interestingly, this species at m/z 544 decreases in time while the presence of the 1:1 Hg(II):GSH conjugate increases, suggesting that m/z 544 is an intermediate in the formation of the 1:1 conjugate. Experiments using the high mass accuracy capability of Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry coupled to an electrospray ionization source indicate that the intermediate species is [GSH + HgCl]+, andnotthe 1:1 conjugate [Hg(GSH) – H + 2H2O]+postulated in previous literature. Further confirmation of [GSH + HgCl]+ is supported by collisionofinduced dissociation experiments, which show neutral loss of HCl from the intermediate and loss of the N- and C-terminal amino acids, indicating binding of Hg(II) at the Cys residue.

Share and Cite:

Fine, Z. and D. Wood, T. (2013) Formation of Mercury(II)-Glutathione Conjugates Examined Using High Mass Accuracy Mass Spectrometry. International Journal of Analytical Mass Spectrometry and Chromatography, 1, 90-94. doi: 10.4236/ijamsc.2013.12011.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] M. Valko, D. Leibfritz, J. Moncol, M. T. Cronin, M. Mazur and J. Telser, “Free Radicals and Antioxidants in Normal Physiological Functions and Human Disease,” International Journal of Biochemistry & Cell Biology, Vol. 39, No. 1, 2007, pp. 44-84.
[2] H. Xu and M. Hepel, “Molecular Beacon-Based Fluorescent Assay for Selective Detection of Glutathione and Cysteine,” Analytical Chemistry, Vol. 83, No. 3, 2011, pp. 813-819.
[3] M. Valko, H. Morris and M. T. Cronin, “Metals, Toxicity and Oxidative Stress,” Current Medicinal Chemistry, Vol. 12, No. 10, 2005, pp. 1161-1208.
[4] W. Stricks and I. M. Koltoff, “Reactions between Mercuric Mercury and Cysteine and Glutathione. Apparent Dissociation Constants, Heats and Entropies of Formation of Various Forms of Mercuric Mercapto-Cysteine and -Glutathione,” Journal of the American Chemical Society, Vol. 75, No. 22, 1953, pp. 5673-5681.
[5] B. J. Fuhr and D. L. Rabenstein, “Nuclear Magnetic Resonance Studies of the Solution Chemistry of Metal Complexes. IX. The Binding of Cadmium, Zinc, Lead, and Mercury by Glutathione,” Journal of the American Chemical Society, Vol. 95, No. 21, 1973, pp. 6944-6950.
[6] R. K. Zalups, “Molecular Interactions with Mercury in the Kidney,” Pharmacological Reviews, Vol. 52, 2000, pp. 113-143.
[7] V. Mah and F. Jalilehvand, “Glutathione Complex Formation with Mercury(II) in Aqueous Solution at Physiological pH,” Chemical Research in Toxicology, Vol. 23 , No. 11, 2010, pp. 1815-1823.
[8] E. M. Krupp, B. F. Milne, A. Mestrot, A. A. Meharg and J. Feldmann, “Investigation into Mercury Bound to Biothiols: Structural Identification Using ESI-Ion-Trap MS and Introduction of a Method for Their HPLC Separation with Simultaneous Detection by ICP-MS and ESI-MS,” Analytical and Bioanalytical Chemistry, Vol. 390, No. 7, 2008, pp. 1753-1764.
[9] F. M. Rubino, M. Pitton, G. Brambilla and A. Colombi, “A Study of the Glutathione Metaboloma Peptides by Energy-Resolved Mass Spectrometry as a Tool to Investigate into the Interference of Toxic Heavy Metals with Their Metabolic Processes,” Journal of Mass Spectrometry, Vol. 41, No. 12, 2006, pp. 1578-1593.
[10] N. Burford, M. D. Eelman and K. Groom, “Identification of Complexes Containing Glutathione with As(III), Sb(III), Cd(II), Hg(II), Tl(I), Pb(II) or Bi(III) by Electrospray Ionization Mass Spectrometry,” Journal of Inorganic Biochemistry, Vol. 99, No. 10, 2005, pp. 1992- 1997.
[11] F. M. Rubino, C. Verduci, R. Giampiccolo, S. Pulvirenti, G. Brambilla and A. Colombi, “Molecular Characterization of Homo- and Heterodimeric Mercury(II)-Bis- Thiolates of Some Biologically Relevant Thiols by Electrospray Ionization and Triple Quadrupole Tandem Mass Spectrometry,” Journal of the American Society for Mass Spectrometry, Vol. 15, No. 3, 2004, pp. 288-300.
[12] S. J. James, P. Cutler, S. Melnyk, S. Jernigan, L. Janak, D. W. Gaylor and J. A. Neubrander, “Metabolic Biomarkers of Increased Oxidative Stress and Impaired Methylation Capacity in Children with Autism,” American Journal of Clinical Nutrition, Vol. 80, No. 6, 2004, pp. 1611-1617.
[13] J. Mutter, J. Naumann, R. Schneider, H. Wallach and B. Haley, “Mercury and Autism: Accelerating Evidence?” Neuro Endocrinology Letters, Vol. 26, 2005, pp. 439-446.
[14] T. W. Clarkson and L. Magos, “The Toxicology of Mercury and Its Chemical Compounds,” Critical Reviews in Toxicology, Vol. 36, No. 8, 2006, pp. 609-662.
[15] P. Caravatti and M. Allemann, “The Infinity Cell—A New Trapped Ion Cell with Radiofrequency Covered Trapping Electrodes for Fourier Transform Ion Cyclotron Resonance Mass Spectrometry,” Organic Mass Spectrometry, Vol. 26, No. 5, 1991, pp. 514-518.
[16] A. G. Marshall, C. L. Hendrickson and G. S. Jackson, “Fourier Transform Ion Cyclotron Resonance Mass Spectrometry: A Primer,” Mass Spectrometry Reviews, Vol. 17, No. 1, 1998, pp. 1-35.<1::AID-MAS1>3.0.CO;2-K
[17] A. G. Harrison, “Ion Chemistry of Protonated Glutamic Acid Derivatives,” International Journal of Mass Spectrometry, Vol. 210, 2001, pp. 361-370.
[18] A. G. Harrison, “Fragmentation Reactions of Protonated Peptides Containing Glutamine or Glutamic Acid,” Journal of Mass Spectrometry, Vol. 38, No. 2, 2003, pp. 136-144.

Copyright © 2020 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.