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Peroxiredoxins (Prxs, ; HGNC root symbol ''PRDX'') are a ubiquitous family of antioxidant enzymes that also control cytokine-induced peroxide levels and thereby mediate signal transduction in mammalian cells. The family members in humans are PRDX1, PRDX2, PRDX3, PRDX4, PRDX5, and PRDX6. The physiological importance of peroxiredoxins is illustrated by their relative abundance (one of the most abundant proteins in erythrocytes after hemoglobin is peroxiredoxin 2). == Classification == Peroxiredoxins can be regulated by changes to phosphorylation, redox and possibly oligomerization states. They are divided into three classes: *Typical 2-Cys Prxs *Atypical 2-Cys Prxs and *1-Cys Prxs. These enzymes share the same basic catalytic mechanism, in which a redox-active cysteine (the peroxidatic cysteine) in the active site is oxidized to a sulfenic acid by the peroxide substrate. The recycling of the sulfenic acid back to a thiol is what distinguishes the three enzyme classes. 2-Cys peroxiredoxins are reduced by thiols such as glutathione, while the 1-Cys enzymes may be reduced by ascorbic acid or glutathione in the presence of GST-π. Using crystal structures, a detailed catalytic cycle has been derived for typical 2-Cys Prxs, including a model for the redox-regulated oligomeric state proposed to control enzyme activity. Inactivation of these enzymes by over-oxidation of the active thiol to sulfinic acid can be reversed by sulfiredoxin. Peroxiredoxins are frequently referred to as alkyl hydroperoxide reductase (AhpC) in bacteria. Other names include thiol specific antioxidant (TSA). This family contains AhpC and TSA, as well as related proteins. Mammals express six peroxiredoxins: * 1-Cys enzymes: PRDX6 * 2-Cys enzymes: PRDX1, PRDX2, PRDX3, PRDX4, and PRDX5 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Peroxiredoxin」の詳細全文を読む スポンサード リンク
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