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MINOR CREDIT SEMINARPeroxiredoxins: Guardians against oxidative stress and modulators of peroxide signalling
Submitted by: Arya Prakash PandaRoll no-M-5687
Animal Biochemistry
Peroxiredoxin
s
Glutathione peroxidase
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…
-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?
E.C-1.11.1.15 according to HGNC.Located primarily in cytosolRecently 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…..
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
Wood ZA, et al. Trends Biochem. Sci. 28 (1): 32–40.
Mechanism
Perkins A et al. Trends in Biochem. Sci. 40 (8): 435–445
Conformational changes
Wood ZA, Schröder E, Harris JR, Trends Biochem Sci. 2003; 28:32–40.
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
OXIDATIVE STRESS
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
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 H2O2mediated Signaling process
Woojin Jeong, Tong-Shin Chang et al. Current Opinion in Cell Biology 2005, 17:183–189
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
PTP
www.fibrogenesis.com
PTEN
jcs.biologists.org
Reversible inactivation of PTPS & PTEN in cells
Kang W.S et al Current opinion in cell Bio. 17 (2): 183-189
Elimination of H2O2 by Prxs
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
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
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