Oxidoreductases;
Acting on a peroxide as acceptor;
Peroxidases
BRITE hierarchy

thioredoxin:hydroperoxide oxidoreductase

thioredoxin + ROOH = thioredoxin disulfide + H2O + ROH [RN:R12570]

R12570
Reaction

thioredoxin [CPD:C00342];
ROOH [CPD:C15498]

Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant proteins. They can be divided into three classes: typical 2-Cys, atypical 2-Cys and 1-Cys peroxiredoxins [4]. The peroxidase reaction comprises two steps centred around a redox-active cysteine called the peroxidatic cysteine. All three peroxiredoxin classes have the first step in common, in which the peroxidatic cysteine attacks the peroxide substrate and is oxidized to S-hydroxycysteine (a sulfenic acid) (see {single/111115a::mechanism}). The second step of the peroxidase reaction, the regeneration of cysteine from S-hydroxycysteine, distinguishes the three peroxiredoxin classes. For typical 2-Cys Prxs, in the second step, the peroxidatic S-hydroxycysteine from one subunit is attacked by the 'resolving' cysteine located in the C-terminus of the second subunit, to form an intersubunit disulfide bond, which is then reduced by one of several cell-specific thiol-containing reductants completing the catalytic cycle. In the atypical 2-Cys Prxs, both the peroxidatic cysteine and its resolving cysteine are in the same polypeptide, so their reaction forms an intrachain disulfide bond. The 1-Cys Prxs conserve only the peroxidatic cysteine, so its regeneration involves direct interaction with a reductant molecule. Thioredoxin-dependent peroxiredoxins are the most common. They have been reported from archaea, bacteria, fungi, plants, and animals.

EC 1.11.1.24 created 1983 as EC 1.11.1.15, part transferred 2020 to EC 1.11.1.24