Thiol peroxidase Tpx (IPR002065)

Short name: TPX

Overlapping homologous superfamilies

Family relationships



Escherichia coli protein Tpx [PMID: 7499381] is a bacterial, periplasmic antioxidant protein with a thiol peroxidase activity. It is a small protein of 18 kDa whose sequence is well conserved in other bacterial species. Tpx which differs from other peroxidases (PRXs) in that it shows substrate specificity toward alkyl hydroperoxides over hydrogen peroxide. As with all other PRXs, the peroxidatic cysteine (N-terminal) of Tpx is oxidized into a sulfenic acid intermediate upon reaction with peroxides. Tpx is able to resolve this intermediate by forming an intramolecular disulfide bond with a conserved C-terminal cysteine (the resolving cysteine), which can then be reduced by thioredoxin [PMID: 14506251]. This differs from the typical 2-cys PRX which resolves the oxidized cysteine by forming an intermolecular disulfide bond with the resolving cysteine from the other subunit of the homodimer. Atypical 2-cys PRX homodimers have a loop-based interface (A-type for alternate), in contrast with the B-type interface of typical 2-cys and 1-cys PRXs [PMID: 12517450].

GO terms

Biological Process

GO:0055114 oxidation-reduction process

Molecular Function

GO:0016209 antioxidant activity
GO:0008379 thioredoxin peroxidase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.