InterPro: IPR000889 Glutathione peroxidase

Glutathione peroxidase (GSHPx) (EC:1.11.1.9) is an enzyme that catalyses the reduction of hydroxyperoxides by glutathione [1, 2]. Its main function is to protect against the damaging effect of endogenously formed hydroxyperoxides. In higher vertebrates, several forms of GSHPx are known, including a ubiquitous cytosolic form (GSHPx-1), a gastrointestinal cytosolic form (GSHPx-GI), a plasma secreted form (GSHPx-P), and an epididymal secretory form (GSHPx-EP). In addition to these characterised forms, the sequence of a protein of unknown function [3] has been shown to be evolutionary related to those of GSHPx's.

In filarial nematode parasites, the major soluble cuticular protein (gp29) is a secreted GSHPx, which may provide a mechanism of resistance to the immune reaction of the mammalian host by neutralising the products of the oxidative burst of leukocytes [4]. The Escherichia coli protein btuE, a periplasmic protein involved in vitamin B12 transport, is evolutionarily related to GSHPxs, although the significance of this relationship is unclear. The structure of bovine seleno-glutathione peroxidase has been determined [5]. The protein belongs to the alpha-beta class, with a 3 layer(aba) sandwich architecture. The catalyic site of GSHPx contains a conserved residue which is either a cysteine or, in many eukaryotic GSHPx, a selenocysteine [6].