Peroxiredoxin: Difference between revisions

Latest revision as of 11:21, 15 February 2025

Overview[edit]

Peroxiredoxins are a family of antioxidant enzymes that play a crucial role in reducing peroxides, such as hydrogen peroxide and organic hydroperoxides, to water and alcohols, respectively. They are found in a wide range of organisms, from bacteria to humans, and are involved in protecting cells from oxidative damage.

Structure[edit]

Peroxiredoxins are characterized by their cysteine-based catalytic mechanism. The active site of peroxiredoxins contains a conserved cysteine residue, known as the peroxidatic cysteine, which is essential for their enzymatic activity. Upon reaction with a peroxide substrate, this cysteine is oxidized to a sulfenic acid intermediate.

Mechanism of Action[edit]

Peroxiredoxins function through a catalytic cycle that involves the reduction of peroxides. The peroxidatic cysteine is oxidized to cysteine sulfenic acid, which is then reduced back to cysteine by a thiol-containing reducing agent, such as thioredoxin. This cycle allows peroxiredoxins to continuously detoxify peroxides in the cell.

Types of Peroxiredoxins[edit]

There are several types of peroxiredoxins, classified based on their structure and the number of cysteine residues involved in the catalytic cycle:

1-Cys Peroxiredoxins: These have only one conserved cysteine residue involved in the catalytic cycle.
2-Cys Peroxiredoxins: These have two conserved cysteine residues, forming an intermolecular disulfide bond during the catalytic cycle.
Atypical 2-Cys Peroxiredoxins: These have two cysteine residues but form an intramolecular disulfide bond.

Biological Functions[edit]

Peroxiredoxins are involved in various cellular processes, including:

Antioxidant Defense: They protect cells from oxidative stress by reducing peroxides.
Signal Transduction: They participate in redox signaling by modulating the activity of other proteins through reversible oxidation.
Cell Proliferation and Differentiation: They are involved in regulating cell growth and differentiation.

Clinical Significance[edit]

Alterations in peroxiredoxin expression and function have been associated with various diseases, including cancer, neurodegenerative disorders, and cardiovascular diseases. Their role in maintaining redox balance makes them potential targets for therapeutic intervention.

Related Pages[edit]

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-'''Peroxiredoxin''' (Prx) is a family of [[antioxidant]] enzymes that play a critical role in cellular defense against [[oxidative stress]] by reducing [[peroxide]]s, including [[hydrogen peroxide]] (H<sub>2</sub>O<sub>2</sub>), organic hydroperoxides, and peroxynitrite. These enzymes are ubiquitous, found in a wide range of living organisms from [[bacteria]] to [[mammals]], and are essential for protecting cells from oxidative damage, which can lead to various diseases such as [[cancer]], [[neurodegenerative diseases]], and [[aging]].
+{{DISPLAYTITLE:Peroxiredoxin}}
-== Structure and Mechanism ==
+== Overview ==
-Peroxiredoxins are small [[protein]]s, typically consisting of 150-200 [[amino acid]]s. They can be classified into three major classes based on their catalytic mechanism: 1-Cys, 2-Cys, and atypical 2-Cys Prx. The classification is based on the number and position of [[cysteine]] residues involved in the catalytic cycle. The 2-Cys Prx, the most common type, forms a disulfide bond during the reduction of peroxides, which is then reduced back by [[thioredoxin]], completing the catalytic cycle.
+[[File:Peroxiredoxin.png|thumb|right|Structure of Peroxiredoxin]]
+'''Peroxiredoxins''' are a family of antioxidant [[enzyme]]s that play a crucial role in reducing [[peroxide]]s, such as [[hydrogen peroxide]] and organic hydroperoxides, to water and alcohols, respectively. They are found in a wide range of organisms, from bacteria to humans, and are involved in protecting cells from oxidative damage.
-The mechanism of action of peroxiredoxins involves the reduction of peroxide substrates by a peroxidatic cysteine (C<sub>P</sub>), leading to the formation of a sulfenic acid intermediate. In 2-Cys Prx, this intermediate then forms a disulfide bond with a resolving cysteine (C<sub>R</sub>) from another Prx molecule or the same one, depending on the specific type of Prx. This disulfide bond is subsequently reduced by thioredoxin, regenerating the active form of Prx.
+== Structure ==
+Peroxiredoxins are characterized by their [[cysteine]]-based catalytic mechanism. The active site of peroxiredoxins contains a conserved cysteine residue, known as the peroxidatic cysteine, which is essential for their enzymatic activity. Upon reaction with a peroxide substrate, this cysteine is oxidized to a sulfenic acid intermediate.
+== Mechanism of Action ==
+Peroxiredoxins function through a catalytic cycle that involves the reduction of peroxides. The peroxidatic cysteine is oxidized to cysteine sulfenic acid, which is then reduced back to cysteine by a thiol-containing reducing agent, such as [[thioredoxin]]. This cycle allows peroxiredoxins to continuously detoxify peroxides in the cell.
+== Types of Peroxiredoxins ==
+There are several types of peroxiredoxins, classified based on their structure and the number of cysteine residues involved in the catalytic cycle:
+* '''1-Cys Peroxiredoxins''': These have only one conserved cysteine residue involved in the catalytic cycle.
+* '''2-Cys Peroxiredoxins''': These have two conserved cysteine residues, forming an intermolecular disulfide bond during the catalytic cycle.
+* '''Atypical 2-Cys Peroxiredoxins''': These have two cysteine residues but form an intramolecular disulfide bond.
 == Biological Functions ==
-Peroxiredoxins play several vital roles in cellular physiology beyond their antioxidant function. They are involved in the regulation of [[cell proliferation]], [[apoptosis]] (programmed cell death), and [[signal transduction]] pathways related to the cellular response to oxidative stress. By controlling the levels of H<sub>2</sub>O<sub>2</sub>, Prxs modulate the activity of various [[transcription factors]] and signaling molecules, influencing gene expression and cell fate decisions.
+Peroxiredoxins are involved in various cellular processes, including:
+* '''Antioxidant Defense''': They protect cells from oxidative stress by reducing peroxides.
+* '''Signal Transduction''': They participate in redox signaling by modulating the activity of other proteins through reversible oxidation.
+* '''Cell Proliferation and Differentiation''': They are involved in regulating cell growth and differentiation.
 == Clinical Significance ==
-Alterations in peroxiredoxin expression and function have been linked to a variety of human diseases. Overexpression of certain Prxs has been observed in various cancers, where they may contribute to tumor progression by protecting cancer cells from oxidative damage and apoptosis. Conversely, reduced Prx activity is associated with increased susceptibility to oxidative stress-related diseases, such as neurodegenerative disorders (e.g., [[Alzheimer's disease]], [[Parkinson's disease]]), suggesting that Prxs could be potential targets for therapeutic intervention.
+Alterations in peroxiredoxin expression and function have been associated with various diseases, including cancer, neurodegenerative disorders, and cardiovascular diseases. Their role in maintaining redox balance makes them potential targets for therapeutic intervention.
-== Types of Peroxiredoxins ==
+== Related Pages ==
-There are six known isoforms of peroxiredoxin in mammals, Prx I-VI, each with distinct cellular localizations and functions. For example, Prx I-IV are typically located in the cytosol and nucleus, Prx V is found in mitochondria and peroxisomes, and Prx VI is present in the cytosol and lysosomes.
+* [[Antioxidant]]
+* [[Enzyme]]
-== Research and Future Directions ==
+* [[Oxidative stress]]
-Research on peroxiredoxins continues to uncover their complex roles in cellular physiology and their potential as biomarkers and therapeutic targets for various diseases. Understanding the precise mechanisms by which Prxs regulate oxidative stress and cell signaling could lead to the development of novel strategies for the prevention and treatment of diseases associated with oxidative damage.
+* [[Thioredoxin]]
+[[Category:Enzymes]]
 [[Category:Antioxidants]]
-[[Category:Enzymes]]
-[[Category:Cell biology]]
-{{enzyme-stub}}