Crystal structure of Equus ferus caballus glutathione transferase A3-3 in complex with glutathione and triethyltin

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 

Starting Model: experimental
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This is version 1.2 of the entry. See complete history


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

Skerlova, J.Ismail, A.Lindstrom, H.Sjodin, B.Mannervik, B.Stenmark, P.

(2021) Environ Pollut 268: 115960-115960

  • DOI: https://doi.org/10.1016/j.envpol.2020.115960
  • Primary Citation of Related Structures:  
    6ZJ9, 6ZJC

  • PubMed Abstract: 

    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.

  • Organizational Affiliation

    Department of Biochemistry and Biophysics, Stockholm University, SE-10691, Stockholm, Sweden.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Glutathione S-transferaseA [auth B],
B [auth A],
C [auth D],
D [auth C]
222Equus caballusMutation(s): 0 
Gene Names: GSTA3
Find proteins for M9ZT87 (Equus caballus)
Explore M9ZT87 
Go to UniProtKB:  M9ZT87
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupM9ZT87
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
GSH (Subject of Investigation/LOI)
Query on GSH

Download Ideal Coordinates CCD File 
E [auth B],
H [auth A],
K [auth D],
N [auth C]
C10 H17 N3 O6 S
QLT (Subject of Investigation/LOI)
Query on QLT

Download Ideal Coordinates CCD File 
F [auth B],
I [auth A],
L [auth D],
O [auth C]
Triethyltin bromide
C6 H15 Br Sn
Query on MPD

Download Ideal Coordinates CCD File 
G [auth B],
J [auth A],
M [auth D],
P [auth C]
C6 H14 O2
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.173 
  • R-Value Observed: 0.175 
  • Space Group: P 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 49.401α = 88.17
b = 54.728β = 78.74
c = 97.115γ = 86.39
Software Package:
Software NamePurpose
Aimlessdata scaling
PDB_EXTRACTdata extraction
DIALSdata reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Swedish Research CouncilSweden2015-04222
Swedish Research CouncilSweden2018-03406
European Regional Development FundEuropean UnionCZ.02.2.69/0.0/0.0/16_027/0008477

Revision History  (Full details and data files)

  • Version 1.0: 2020-11-18
    Type: Initial release
  • Version 1.1: 2020-12-23
    Changes: Database references
  • Version 1.2: 2024-01-31
    Changes: Data collection, Database references, Refinement description