How many superoxide dismutase (SOD) genes are in E. coli, B

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How many superoxide dismutase (SOD) genes are in E. coli, B
Antioxidant enzymes
Group members
Arunakumar Gangaplara
Cecilia Jädert
Chandirasegaran Massilamany
Mohammad Pirmoradian N
How many superoxide dismutase
(SOD) genes are in E. coli, B. subtilis,
S. cerevisiae and humans? Where are
the SODs localized?
Arunakumar Gangaplara
University of Nebraska-Lincoln
Organism
Gene/Product
Localization
E. coli
SodA/Mn-SOD
Cytoplasm/interacting
with bacterial DNA
SodB/Fe-SOD
Inner membrane
SodC/Cu, Zn-SOD
Periplasm
SodA/Mn-SOD
Cytoplasm
B. subtilis
S. cervisiae Sod1/Cu, Zn-SOD
H. sapiens
Cytoplasm
Sod2/Mn-SOD
Mitochondrial matrix
Sod1/Cu, Zn-SOD
Cytosol
Sod2/Mn-SOD
Mitochondria
Sod3/Extracellular Extracellular space
Cu, Zn-SOD
(Miller AF, 2012; Inaoka T et al, 1998; Park J et al, 1998)
Note: Orange-FeSOD, Magenta-MnSOD, Blue-Cu,ZnSOD and Green-NiSOD
(Miller AF, 2012)
How many catalase genes are in E.
cole, B. subtilis, S. cervisiae, and
humans? What cofactor does catalase
require? Where are the different
catalase enzymes localized?
Cecilia Jädert
Karolinska Institutet
Catalase cofactors
• Key antioxidant enzyme in defense against oxidative stress
• Overall reaction 
• Heme-containing enzyme
• Monofunctional – most common
• Bifunctional
• Mn-containing enzyme (dimanganese)
• NADPH – not sure about function
(Chelikani P, Cell Mol Life Sci, 2004)
Genes of catalase
• E. coli (Uhlich GA, Microbiology, 2009)
– KatE, KatF, KatG, KatP
– cytosol
• B. subtilis (Naclerio G, Appl Environ Microbiol, 1995) (Bagyan I, J Bacteriology, 1998)
– KatA, KatX (after sporulation)
– Extracellular
• S. cerevisiae (Bayliak M, Biochemistry, 2008)
– CTA1 cytosol
– CTT1 peroxisome
• H. Sapiens
– CAT peroxisome
How do peroxiredoxins protect cells
against oxidative stress? Describe the
reaction catalyzed by peroxiredoxins.
Chandirasegaran Massilamany
University of Nebraska-Lincoln
Peroxiredoxins
Peroxiredoxins are group of thiol-based enzymes
They protect the cells against oxidative stress by catalyzing
the reduction of hydrogen peroxide (H2O2), organic
hydroperoxides (ROOH) and peroxynitrites (ONOO-)
Divided into three major subclasses:
 2-cys peroxiredoxins (Prx I-IV)
 Atypical 2-cys peroxiredoxins (Prx V)
 1-cys peroxiredoxins (Prx VI)
Tavender and Bulleid, 2010; Immenschuh and Baumgart-Vogt, 2005; Rhee, et al., 2005
Peroxiredoxins
Distribution of Peroxiredoxins within the cell:
Prx I, II – cytosol
Prx III – mitochondria
Prx IV – extracellular space
Prx V – mitochondria and peroxisomes
Prx VI – cytosol
Tavender and Bulleid, 2010; Immenschuh and Baumgart-Vogt, 2005; Rhee, et al., 2005
Reaction catalyzed by peroxiredoxins:
Poole, L.B., Peroxiredoxins. In Redox Biochemistry, 2007 (Ed) Banerjee, R
What is the function and mechanism
of glutathione peroxidase?
Where is it localized in mammalian
cells?
Mohammad Pirmoradian N.
Karolinska Institutet
1/16/12
M. Pirmoradian
12
function and mechanism
• Peroxidase:
– ROOR' + electron donor (2 e-) + 2H+ → ROH +
R'OH
• Glutathione peroxidase
– 2GSH + H2O2 → GS–SG + 2H2O
• They mostly reduces:
– lipid hydroperoxides to alcohols
– hydrogen peroxide to water.
• GPx1 to 6 (except 5) are selenoprotein
– Active site is at the selenocysteine site
• GPx1 to 3 are homotetramer, and GPx4 is a
monomer
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M. Pirmoradian
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function and mechanism
Kakihana T. et al.(2012) Antioxid. Redox Signal. 16, 763–771.
1/16/12
M. Pirmoradian
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Location in mammalian cells
• Glutathione peroxidase 1 (GPx1):
– the most abundant version
– Located in the cytoplasm of nearly all
mammalian tissues
– The substrate is hydrogen peroxide
• Glutathione peroxidase 2 (GPx2):
– is an intestinal and intracellular enzyme
• Glutathione peroxidase 3 (GPx3):
– is extracellular, especially in plasma
• Glutathione peroxidase 4 (GPx4):
– The substrate is lipid hydroperoxides
1/16/12– expressed in nearly M.
Pirmoradianmammalian cell
every
15
Location in mammalian cells
Florian L. et al. (2007). Free Radical Biology and Medicine, 43:4, 477-503
1/16/12
M. Pirmoradian
16

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