PDBsum entry 1yzx

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Transferase PDB id
Protein chain
218 a.a.
GSF ×2
Waters ×179

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Key reference
Title Thioredoxin-Like domain of human kappa class glutathione transferase reveals sequence homology and structure similarity to the theta class enzyme.
Authors J.Li, Z.Xia, J.Ding.
Ref. Protein Sci, 2005, 14, 2361-2369. [DOI no: 10.1110/ps.051463905]
PubMed id 16081649
Glutathione transferases (GSTs) are a superfamily of enzymes that play a vital functional role in the cellular detoxification process. They catalyze the conjugation of the thiol group of glutathione (GSH) to the electrophilic groups of a wide range of hydrophobic substrates, leading to an easier removal of the latter from the cells. The kappa class is the least studied one among various classes within the superfamily. We report here the expression, purification, and crystal structure of human kappa class GST (hGSTK), which has been determined by the multiple-isomorphous replacement method and refined to 1.93 A resolution. The overall structure of hGSTK is similar to the recently reported structure of kappa class GST from rat mitochondrion. Each subunit of the dimeric hGSTK contains a thioredoxin (TRX)-like domain and a helical domain. A molecule of glutathione sulfinate, an oxidized product of GSH, is found to bind at the G site of each monomer. One oxygen atom of the sulfino group of GSF forms a hydrogen bond with the hydroxyl group of the catalytic residue Ser16. The TRX-like domain of hGSTK shares 19% sequence identity and structure similarity with human theta class GST, suggesting that the kappa class of GST is more closely related to the theta class enzyme within the GST superfamily. The structure of the TRX-like domain of hGSTK is also similar to that of glutathione peroxidase (GPx), implying an evolutionary relationship between GST and GPx.
Figure 2.
Figure 2. Structure of the catalytic active G-site. (A) SIGMAA-weighted 2Fo-Fc electron density map (1 contour level) at the G-site. This diagram was prepared using the program TURBO-FRODO. (B) Hydrogen- bonding interactions of the sulfino group of GSF with Ser16 of hGSTK (left), compared with those of the thiol group of GSH with Ser16 of rGSTK (right). Two water molecules bound to the sulfino group of GSF in hGSTK structure are shown as spheres. Hydrogen bonds are shown as dotted lines. This diagram was prepared using the program SETOR.
The above figure is reprinted by permission from the Protein Society: Protein Sci (2005, 14, 2361-2369) copyright 2005.
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