Redox properties and evolution of human glutaredoxins.

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Sagemark J, Elgan TH, Burglin TR, Johansson C, Holmgren A, Berndt KD

Redox properties and evolution of human glutaredoxins.

Proteins. 2007 Sep 1;68(4):879-92.

PubMed ID

17546662 [ View in PubMed

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Abstract

Glutaredoxins (Grxs) are glutathione-dependent oxidoreductases that belong to the thioredoxin superfamily catalyzing thiol-disulfide exchange reactions via active site cysteine residues. Focusing on the human dithiol glutaredoxins having a C-X-Y-C active site sequence motif, the redox potentials of hGrx1 and hGrx2 were determined to be -232 and -221 mV, respectively, using a combination of redox buffers, protein-protein equilibrium and thermodynamic linkage. In addition, a nonactive site disulfide was identified between Cys28 and Cys113 in hGrx2 using redox buffers and chemical digestion. This disulfide confers nearly five kcal mol(-1) additional stability by linking the C-terminal helix to the bulk of the protein. The redox potential of this nonactive site disulfide was determined to be -317 mV and is thus expected to be present in all but the most reducing conditions in vivo. As all human glutaredoxins contain additional nonactive site cysteine residues, a full phylogenetic analysis was performed to help elucidate their structural and functional roles. Three distinct groups were found: Grx1, Grx2, and Grx5, the latter representing a highly conserved group of monothiol glutaredoxins having a C-G-F-S active site sequence, with clear homologs from bacteria to human. Grx1 and Grx2 diverged from a common ancestor before the origin of vertebrates, possibly even earlier in animal evolution. The highly stabilizing nonactive site disulfide observed in hGrx2 is found to be a conserved feature within the deuterostomes and appears to be the only additional conserved intramolecular disulfide within the glutaredoxins.

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Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Glutathione	Glutaredoxin-2, mitochondrial	Protein	Humans	Unknown	Not Available	Details