Structural and functional analysis of the inhibition of equine glutathione transferase A3-3 by organotin endocrine disrupting pollutants.

The research paper presents an investigation on how organotin compounds, which are highly toxic pollutants, inhibit the function of Equine Glutathione Transferases (EcaGST A3-3). The findings demonstrate that these compounds form strong bonds with the enzyme, blocking its function and contributing to the understanding of organotin compounds’ neurotoxic and endocrine disrupting effects.

Research Objective and Approach

• This study focuses on understanding how organotin compounds, toxic pollutants known for neurotoxic and endocrine-disrupting effects, inhibit the function of specific GST enzymes, particularly equine GST A3-3.
• The approach involves enzyme kinetics analysis and resolving the crystal structures of EcaGST A3-3 in complex with glutathione and with triethyltin, one of the organotin compounds.

Key Findings

• When the EcaGST A3-3 enzyme is in contact with triethyltin, the tin atom forms powerful covalent bonds with glutathione and a tyrosyl residue of the enzyme, blocking the enzyme function. This binding prevents the release of the glutathione-organotin adduct, putting a full halt to the enzyme’s function.
• This shows a pattern of how organotin compounds inhibit GST enzymes. As GST enzymes play a crucial role in detoxification, this inhibition contributes to the organotin compounds’ toxic effects, leading to neurotoxicity and endocrine disruption.

Contribution to the Existing Knowledge

• This research provides a structural basis for understanding the general mechanism of GST enzyme inhibition by organotin compounds.
• The findings broaden our knowledge about the toxicological impacts of these pollutants, especially their neurotoxic and endocrine disrupting effects.