Faculty Collaboration Database

Albumin oxidation to diverse radicals by the peroxidase activity of Cu,Zn-superoxide dismutase in the presence of bicarbonate or nitrite: diffusible radicals produce cysteinyl and solvent-exposed and -unexposed tyrosyl radicals. Biochemistry 2004 Jan 20;43(2):344-51

Date

01/14/2004

Pubmed ID

14717588

DOI

10.1021/bi035606p

Scopus ID

2-s2.0-0347724053 (requires institutional sign-in at Scopus site)   61 Citations

Abstract

The peroxidase activity of Cu,Zn-superoxide dismutase (Cu,Zn-SOD) has been extensively studied in recent years due to its potential relationship to familial amyotrophic lateral sclerosis. The mechanism by which Cu,Zn-SOD/hydrogen peroxide/bicarbonate is able to oxidize substrates has been proposed to be dependent on an oxidant whose nature, diffusible carbonate radical anion or enzyme-bound peroxycarbonate, remains debatable. One possibility to distinguish these species is to examine whether protein targets are oxidized to protein radicals. Here, we used EPR methodologies to study bovine serum albumin (BSA) oxidation by Cu,Zn-SOD/hydrogen peroxide in the absence and presence of bicarbonate or nitrite. The results showed that BSA oxidation in the presence of bicarbonate or nitrite at pH 7.4 produced mainly solvent-exposed and -unexposed BSA-tyrosyl radicals, respectively. Production of the latter was shown to be preceded by BSA-cysteinyl radical formation. The results also showed that hydrogen peroxide/bicarbonate extensively oxidized BSA-cysteine to the corresponding sulfenic acid even in the absence of Cu,Zn-SOD. Thus, our studies support the idea that peroxycarbonate acts as a two-electron oxidant and may be an important biological mediator. Overall, the results prove the diffusible and radical nature of the oxidants produced during the peroxidase activity of Cu,Zn-SOD in the presence of bicarbonate or nitrite.

Author List

Bonini MG, Fernandes DC, Augusto O

MESH terms used to index this publication - Major topics in bold

Antioxidants
Bicarbonates
Cysteine
Diffusion
Electron Spin Resonance Spectroscopy
Electron Transport
Free Radicals
Kinetics
Nitrites
Oxidants
Oxidation-Reduction
Peroxidase
Serum Albumin, Bovine
Solvents
Spin Trapping
Sulfhydryl Compounds
Superoxide Dismutase
Tyrosine