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

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Organotin compounds are highly toxic environmental pollutants with neurotoxic and endocrine-disrupting effects. They are potent inhibitors of glutathione transferases (GSTs), thus impeding their detoxication and antioxidant functions. Several GSTs, including equine GST A3-3 (EcaGST A3-3), exhibit steroid double-bond isomerase activity and are involved in the biosynthesis of testosterone and progesterone. We have performed enzyme kinetics analyses of the inhibition of EcaGST A3-3 by organotin compounds. We have also solved crystal structures of EcaGST A3-3 in complexes with glutathione, and with glutathione together with covalently bound triethyltin. Our structural data indicate that the tin atom forms strong bonds with a covalent character not only with the glutathione, but also with a tyrosyl residue of the enzyme itself, thereby preventing the release of the glutathione-organotin adduct and completely blocking the enzyme function. This work presents a structural basis for the general mechanism of GST inhibition by organotin compounds and contributes to the understanding of their neurotoxic and endocrine disrupting effects.


  • Jana Škerlová
  • Aram Ismail
  • Helena Lindström
  • Birgitta Sjödin
  • Bengt Mannervik
  • Pål Stenmark
Enheter & grupper
Externa organisationer
  • Stockholms universitet

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Biokemi och molekylärbiologi
TidskriftEnvironmental Pollution
Volym268, Part B
Tidigt onlinedatum2020 okt 29
StatusPublished - 2021 jan 1
Peer review utfördJa