Mechanism of Action of Sulforaphane as a Superoxide Radical Anion and Hydrogen Peroxide Scavenger by Double Hydrogen Transfer: A Model for Iron Superoxide Dismutase

2015 ◽  
Vol 119 (25) ◽  
pp. 7825-7836 ◽  
Author(s):  
Ajit Kumar Prasad ◽  
P.C. Mishra
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Dismutase ◽  
Mechanism Of Action ◽  
Radical Anion ◽  
Hydrogen Transfer ◽  
Superoxide Radical ◽  
Iron Superoxide Dismutase ◽  
Superoxide Radical Anion ◽  
Double Hydrogen

Catalytic role of iron-superoxide dismutase in hydrogen abstraction by super oxide radical anion from ascorbic acid

RSC Advances ◽  
2016 ◽  
Vol 6 (89) ◽  
pp. 86650-86662 ◽  
Author(s):  
Manish K. Tiwari ◽  
Phool C. Mishra
Keyword(s):  
Ascorbic Acid ◽  
Superoxide Dismutase ◽  
Active Site ◽  
Radical Anion ◽  
Superoxide Radical ◽  
Hydrogen Abstraction ◽  
Iron Superoxide Dismutase ◽  
Superoxide Radical Anion ◽  
Catalytic Role

The catalytic role of iron-superoxide dismutase (Fe-SOD) in the working of ascorbic acid (AA) as a superoxide radical anion scavenger has been studied by employing a model developed recently for the active site of the enzyme.

scholarly journals Oxidative denitrification of Nω-hydroxy-l-arginine by the superoxide radical anion

1996 ◽  
Vol 317 (1) ◽  
pp. 17-21 ◽  
Author(s):  
Steven A. EVERETT ◽  
Madeleine F. DENNIS ◽  
Kantilal B. PATEL ◽  
Michael R. L. STRATFORD ◽  
Peter WARDMAN
Keyword(s):  
Nitric Oxide ◽  
Superoxide Dismutase ◽  
Catalytic Activity ◽  
Radical Anion ◽  
Superoxide Radical ◽  
Superoxide Radical Anion ◽  
Prototropic Equilibrium ◽  
Ph Dependent ◽  
Oxide Synthase ◽  
Cytochrome P 450

The superoxide radical anion (O2-•) produced during the catalytic activity of nitric oxide synthase (NOS) and cytochrome P-450 has been implicated in the oxidative denitrification of hydroxyguanidines (> C = NOH). The reactivity of the radiolytically generated O2-• radical with Nω-hydroxy-l-arginine (NHA) is pH dependent and appears to parallel the prototropic equilibrium of the hydroxyguanidino group (> C = NOH ⇌ > C = NO- + H+; pK = 8). The Nω-hydroxyguanidino group is more reactive towards O2-• when deprotonated but exhibits negligible reactivity when protonated. Based on a model, the rate constant for the reaction of the O2-• with NHA was estimated as k (O2-•+ > C = NO-) ≈ 200–500 M-1·s-1, which is probably too low to compete with O2-• reactions with NO• or superoxide dismutase, which occur many orders of magnitude faster. The oxidative elimination of NO from NHA by O2-• was not accompanied by the formation of l-citrulline. Since only 21% of NHA will exist in the deprotonated > C = NO- form at physiological pH, it is unlikely that oxidative denitrification of NHA by cytochrome P-450 or NOS-derived O2-• radicals will prove a major free-radical pathway to NO• and l-citrulline.

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