The interaction of thimerosal, an ethylmercury-containing bactericide and fungicide used as preservative in vaccines and other drugs, with free thiols in proteins has been investigated by means of molecular mass spectrometry and elemental speciation analysis.
Background:
Thimerosal (THI, also called thiomersal)) is a mercury-containing compound used as preservative in vaccines and other drugs in concentrations up to 100 mg L-1. Especially in multi-dose ampullae its antibacterial and antifungal properties is meant to prevent microbial contamination during repeated removal of single doses. Already introduced in 1931, Thimerosal never went through extensive safety evaluation. Due to suspected neurotoxic effects Thimerosal has been banned in the European Union in 2001. However, THI is still in use in the US and in developing countries. Current discussions about the toxicity of THI and other organomercury compounds are either centred around effects like autism or the exact functions of molecular mimicry, by which mercury species are suspected to be actively transported in the human body.
The new study:The
research group from the University of Münster, Germany used reversed phase liquid chromatography (LC) hyphenated with either inductively coupled plasma mass spectrometry (ICP-MS) or electrospray mass spectrometry (ESI-MS) detection for studying the interaction of thimerosal with free thiols in proteins. ß-lactoglobulin A (18.4 kDa) from bovine milk and human serum albumin (66.5 kDa) have been used as model substances under conditions mimicking physiological conditions upon an intravenous injection of thimerosal-containing drugs. The results obtained clearly proved the formation of ethylmercury–protein adducts in both cases.
Using tryptic digestion of ß-lactoglobulin A, the binding site of ethylmercury, a free thiol residue in the peptide T13, could be identified. For future work the researchers hope to obtain data with even more relevance to physiological processes by using systems with increasing similarity to human blood, including natural levels of cysteine and glutathione, which are also present in human blood in significant concentrations.
The work will appear in the first issue of the new Journal
Metallomics, to be published January 2009.
The new study
Stefan Trümpler, Wiebke Lohmann,
Björn Meermann,
Wolfgang Buscher,
Michael Sperling,
Uwe Karst,
Interaction of Thimerosal with Proteins - Ethylmercury Adduct Formation of Human Serum Albumin and b-Lactoglobulin A, Metallomics, 1/1 (2009).
DOI: 10.139/b815978e Related studies S.C. Fang, E. Fallin,
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Interaction of methylmercury compounds with albumin, Arch. Toxicol., 64 (1990) 639-643.
DOI: 10.1007/BF01974691 Ruth E. Hoffmeyer, Satya P. Singh, Christian J. Doonan, Andrew R. S. Ross,
Richard J. Hughes, Ingrid J. Pickering, Graham N. George,
Molecular Mimicry in Mercury Toxicology, Chem. Res. Toxicol., 19 (2006) 753-759.
DOI: 10.1021/tx0503449 Ruth E. Hoffmeyer, Satya P. Singh, Christian J. Doonan, Ingrid J. Pickering, Graham N. George,
More on Molecular Mimicry in Mercury Toxicology, Chem. Res. Toxicol., 19 (2006) 1118-1120.
DOI: 10.1021/tx060177s Christy C. Bridges, Rudolfs K. Zalups,
Molecular Mimicry as a Mechanism for the Uptake of Cysteine S-Conjugates of Methylmercury and Inorganic Mercury, Chem. Res. Toxicol., 19 (2006) 1117-1118.
DOI: 10.1021/tx060158i Yan Li, Yan Jiang,
Xiu-Ping Yan,
Probing Mercury Species-DNA Interactions by Capillary Electrophoresis with On-Line Electrothermal Atomic Absorption Spectrometric Detection, Anal. Chem., 78/17 (2006) 6115-6120.
DOI: 10.1021/ac060644a Grazyna Zareba, Elsa Cernichiari, Rieko Hojo, Scott Mc Nitt, Bernard Weiss, Moiz M. Mumtaz, Dennis E. Jones, Thomas W. Clarkson,
Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury, J. Appl. Toxicol., 27/5 (2007) 511-518.
DOI: 10.1002/jat.1272g Yan Li,
Xiu-Ping Yan, Chen Chen, Yun-Long Xia, Yan Jiang,
Human serum albumin-mercurial species interactions, J. Proteome Res., 6/6 (2007) 2277-2286.
DOI: 10.1021/pr0700403 Xing Wu, Hong Liang, Kimberley A. O'Hara, Jack C. Yalowich, Brian B. Hasinoff,
Thiol-modulated mechanisms of the cytotoxicity of thimerosal and inhibition of DNA topoisomerase II alpha, Chem. Res. Toxicol., 21/2 (2008) 483-493.
DOI: 10.1021/tx700341n Eva M. Krupp, Bruce F. Milne, Adrien Mestrot, Andrew A. Meharg,
Jörg 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, Anal. Bioanal. Chem., 390/7 (2008) 1753-1764.
DOI: 10.1007/s00216-008-1927-x Yifei Guo, Liqin Chen, Limin Yang, Qiuquan Wang,
Counting Sulfhydryls and Disulfide Bonds in Peptides and Proteins Using Mercurial Ions as an MS-Tag, J. Am. Soc. Mass Spectrom., 19/8 (2008) 1108-1113.
DOI: 10.1016/j.jasms.2008.05.005
Related EVISA Resources Journals Database: Metallomics Journals Database: Journals related to metallomics Link Database: Toxicity of Thimerosal Link Database: All About Thimerosal News Section: News related to Thimerosal Brief summary: ESI-MS: The tool for the identification of species Brief summary: LC-ICP-MS - The most often used hyphenated system for speciation analysis
Related EVISA News
October 30, 2008: Precautionary approach to methylmercury needed July 10, 2008: Methyl mercury metabolism in man influenced by genetic factors Januar 12, 2008: New California study concludes that thimerosal seems not to be the major cause for autism November 16, 2006: A silent pandemic: Industrial chemicals are impairing the brain development of children worldwide March 24, 2006: Mercury Containing Preservative Alters Immune Function April 27, 2005: New results about toxicity of thimerosal February 11, 2005: New findings about Thimerosal Neurotoxicity last time modified: May 22, 2024
