Crystal structure of human glutathione-S-transferase P1-1 cys-free mutant in complex with S-hexylglutathione at 2.4 A resolution

Experimental Data Snapshot

  • Resolution: 2.40 Å
  • R-Value Free: 0.310 
  • R-Value Work: 0.250 
  • R-Value Observed: 0.253 

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Modulating Catalytic Activity by Unnatural Amino Acid Residues in a Gsh-Binding Loop of Gst P1-1.

Hegazy, U.M.Tars, K.Hellman, U.Mannervik, B.

(2008) J Mol Biol 376: 811

  • DOI: https://doi.org/10.1016/j.jmb.2007.12.013
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The loop following helix alpha2 in glutathione transferase P1-1 has two conserved residues, Cys48 and Tyr50, important for glutathione (GSH) binding and catalytic activity. Chemical modification of Cys48 thwarts the catalytic activity of the enzyme, and mutation of Tyr50 generally decreases the k(cat) value and the affinity for GSH in a differential manner. Cys48 and Tyr50 were targeted by site-specific mutations and chemical modifications in order to investigate how the alpha2 loop modulates GSH binding and catalysis. Mutation of Cys48 into Ala increased K(M)(GSH) 24-fold and decreased the binding energy of GSH by 1.5 kcal/mol. Furthermore, the protein stability against thermal inactivation and chemical denaturation decreased. The crystal structure of the Cys-free variant was determined, and its similarity to the wild-type structure suggests that the mutation of Cys48 increases the flexibility of the alpha2 loop rather than dislocating the GSH-interacting residues. On the other hand, replacement of Tyr50 with Cys, producing mutant Y50C, increased the Gibbs free energy of the catalyzed reaction by 4.8 kcal/mol, lowered the affinity for S-hexyl glutathione by 2.2 kcal/mol, and decreased the thermal stability. The targeted alkylation of Cys50 in Y50C increased the affinity for GSH and protein stability. Characterization of the most active alkylated variants, S-n-butyl-, S-n-pentyl-, and S-cyclobutylmethyl-Y50C, indicated that the affinity for GSH is restored by stabilizing the alpha2 loop through positioning of the key residue into the lock structure of the neighboring subunit. In addition, k(cat) can be further modulated by varying the structure of the key residue side chain, which impinges on the rate-limiting step of catalysis.

  • Organizational Affiliation

    Department of Biochemistry and Organic Chemistry, Biomedical Center, Uppsala University, Box 576, SE-751 23 Uppsala, Sweden.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
209Homo sapiensMutation(s): 4 
UniProt & NIH Common Fund Data Resources
Find proteins for P09211 (Homo sapiens)
Explore P09211 
Go to UniProtKB:  P09211
PHAROS:  P09211
GTEx:  ENSG00000084207 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP09211
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
GTX Binding MOAD:  2J9H Ki: 4.10e+5 (nM) from 1 assay(s)
PDBBind:  2J9H Ki: 4.10e+5 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 2.40 Å
  • R-Value Free: 0.310 
  • R-Value Work: 0.250 
  • R-Value Observed: 0.253 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 59.566α = 90
b = 59.566β = 90
c = 238.35γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-11-14
    Type: Initial release
  • Version 1.1: 2015-09-23
    Changes: Data collection, Derived calculations, Non-polymer description, Other, Version format compliance
  • Version 1.2: 2018-01-17
    Changes: Data collection
  • Version 1.3: 2019-05-08
    Changes: Data collection, Experimental preparation
  • Version 1.4: 2023-12-13
    Changes: Data collection, Database references, Derived calculations, Other, Refinement description