Peroxiredoxins guardians against oxidative stress
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Peroxiredoxins are ubiquitous group of cysteine dependent antioxidant enzymes found in both prokaryotes and eukaryotes help in regulating oxidative stress and modulates peroxide signaliing transduction.
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Peroxiredoxins guardians against oxidative stress
- 1. MINOR CREDIT SEMINAR Peroxiredoxins: Guardians against oxidative stress and modulators of peroxide signalling Submitted by: Arya Prakash Panda Roll no-M-5687 Animal Biochemistry
- 4. O2 + e− → ·O2 − (Reduction of molecular oxygen) 2H+ + ·O2 − + ·O2 − → H2O2 + O2 (Peroxidation) H2O2 → HO · + ·OH (Partial Reduction) H2O2 + H2O2 → H2O + H2O + O2 (Fully Reduced) Chemistry of Peroxides…
- 5. -Peroxiredoxins (Prxs) :Ubiquitous enzymes that have emerged as most important and widespread peroxide scavenging enzymes in all of biology. -Cysteine based peroxidase enzymes that play a dominant role in regulating cell peroxide levels. Karplus,P.A(2014)Free Radic. Biol,Med. 80, 183-190 -Thiol specific antioxidant proteins termed as thiol redoxin peroxidase. -Not only acts as antioxidants but also appear to regulate H2O2 mediated signal transduction. Wood, Z.A. et al(2003) Science 300,650-653 What are Peroxiredoxins?
- 6. E.C-1.11.1.15 according to HGNC. Located primarily in cytosol Recently cellular roles include modulation of H2O2 levels, which have been shown to mediate signaling cascades leading to cell Apoptosis. Wood,Z.A.et al. Science 300,650-653 Additional informations…..
- 7. Prxs exist in six evolutionary subfamilies like Prx1, Prx5, Prx6,Tpx, PrxQ, and AhpE. Prx1-highly expressed -0.1–1% of the soluble protein in the cell -typical 2-Cys Prxs (original type of ‘2-Cys Prx’having both a CP and CR In mammals, Prx1 subfamily enzymes divided into 6 groups( Prxs I-VI) PrxI and PrxII (cytosol and nucleus ) PrxIII (mitochondria), PrxIV(ER), PrxV(peroxisomes, mitochondria, and cytosol) PrxVI, which is cytosolic . PrxQ,Prx5-Bacteria, Plant Tpx & AhpE-Bacteria Prx(I-IV)-Typical 2-Cys, PrxV-Atypical 2-Cys, PrxVI-1 Cys Rhee S, Chae H, Kim K (2005). Free Radic .Biol Med 38 (12): 1543–52. Classification
- 8. Wood ZA, et al. Trends Biochem. Sci. 28 (1): 32–40.
- 9. Mechanism Perkins A et al. Trends in Biochem. Sci. 40 (8): 435–445
- 10. Conformational changes Wood ZA, Schröder E, Harris JR, Trends Biochem Sci. 2003; 28:32–40.
- 12. It is the state in which oxidation exceeds the antioxidant systems in the body secondary to a loss of the balance between them. Imbalance between oxidants(ROS) and antioxidants(Prx, catalase, Gpx) Oxidative stress
- 13. OXIDATIVE STRESS
- 14. Reduce >90% of cellular peroxides. Can detect less concentration like 10 μM H2O2 in cell. Some eukaryotic Prxs are inherent to hyperoxidative inactivation by H2O2 Prxs in Stress… Perkins A et al. Trends Biochem. Sci. 40 (8): 435–445
- 15. Not only oxidative stress defense enzymes but also regulators of peroxide levels in cells in stress response signaling. Act as 2nd messenger in GF signalling, angiogenesis. NADPH oxidase complex(Nox) are the source. Localization of H2O2 mediated Signaling process Woojin Jeong, Tong-Shin Chang et al. Current Opinion in Cell Biology 2005, 17:183–189
- 16. Protein tyrosine phosphatase(PTP) and Phosphatase Tensin homolog lipid phosphatase (PTEN) which is regulated by Prxs. PTPs-Proteins of low pKa of 4.7-5.4 Cysteine residues. It Undergoes H2O2 dependent inactivation in cells (Cys–S to Cys–SOH). PTEN is a member of PTP family oxidised by H2O2 to intramolecular disulfide with Cys71 So oxidative inhibition of PTEN. Target molecules Sue Goo Rhee et al Current opinion in cell Bio. 17 (2): 183-189
- 19. Reversible inactivation of PTPS & PTEN in cells Kang W.S et al Current opinion in cell Bio. 17 (2): 183-189
- 20. Elimination of H2O2 by Prxs
- 21. Prxs ubiquitous group of antioxidant enzymes contain conserved Cys residues present in cytosol,mitochondria, ER as well as Nucleus. Plays important role in maintaining peroxide levels in cell as well as function as a guard against oxidative stress. Plays a key role in signaling. Conclusion
- 22. Karplus,P.A, A primer on perxiredoxin biochemistryFree Radic. Biol,Med. 80, 183-190(2014) Wood, Z.A, Peroxiredoxin evolution and the regulation of hydrogen peroxide signaling. Science 300, 650–653(2003) Woo, H.A., Reversing the inactivation of peroxiredoxins caused by cysteine sulfinic acid formation. Science 300, 653– 656 ( 2003) Perkins A, Peroxiredoxins: guardians against oxidative stress and modulators of peroxide signaling Trends Biochem. Sci. 40 (8): 435–445(2015) Rhee S.G., Intracellular messenger function of hydrogen peroxide and its regulation by peroxiredoxins, Current opinion in cell Bio. 17 (2): 183-189(2005) REFERENCES
Notas do Editor
- also found in Mitochondria, Choloroplast & peroxisome associated with nuclei. Prxs are produced at high levels in cells: they are among the ten most abundant proteins in E. coli, the second or third most abundant protein in erythrocytes and composed of 0.1–0.8% of the soluble protein in other mammalian cells.
- Prxs were recognized to exist in ‘1-Cys’ and ‘2-Cys’ groups based on the presence or absence of the C-terminal CR now known to be largely characteristic of the Prx1 group ( typical 2-Cys’ group containing both CP & CR) CP termed as Peroxidatic Cysteine which is conserved and reactive Cys residue in the N-terminal region, and are capable of serving as a peroxidase and involve thioredoxin as the electron donor, CR is termed as Resolving Cysteine in PrxI to PrxIV( Cys residue in the conserved C-terminal region). PrxVI has only one unique Cys.
- Dimeric 2-Cys Prxs (individual monomers colored gray or green) in which the peroxidatic cysteine (SP ) is present as an overoxidized sulfinic acid (ball and stick) or in a disulfide with the resolving cysteine (SR)