title: Reactivity of superoxide anion radical with a perchlorotriphenylmethyl (trityl) radical.
abstract: The reaction of superoxide radical with a tricarboxylate derivative of perchlorotriphenylmethyl radical (PTM-TC) is studied. PTM-TC is a stable ("inert") free radical, which gives a single sharp electron paramagnetic resonance (EPR) peak in aqueous solutions. PTM-TC also gives a characteristic optical absorption at 380 nm. Superoxide, on reaction with PTM-TC, induced a decrease in the intensity of the EPR signal and optical absorption of PTM-TC at 380 nm. The signal loss was specific to superoxide and linearly dependent on the superoxide flux in the system. Competitive kinetics experiments revealed that PTM-TC reacts with superoxide with an apparent second-order rate constant of 8.3x10(8) M(-1) s(-1). Electrochemical and mass spectrometric analyses of the reaction suggested the formation of perchlorotriphenylmethane and molecular oxygen as products. The high sensitivity of detection of PTM-TC combined with the high rate constant of the reaction of superoxide with PTM-TC may offer a potential opportunity for measurement of superoxide in biological systems. In conclusion, the PTM-TC molecule has high sensitivity and specificity for superoxide radicals and thus may enable quantitative detection of superoxide generation in biological systems using EPR and/or spectrophotometric methods.
authors: Center for Biomedical EPR Spectroscopy and Imaging, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, Ohio 43210, USA.
authors: Vijay Kumar
authors: VK
authors: Kutala
authors: Frederick A
authors: FA
authors: Villamena
authors: Govindasamy
authors: G
authors: Ilangovan
authors: Daniel
authors: D
authors: Maspoch
authors: Nans
authors: N
authors: Roques
authors: Jaume
authors: J
authors: Veciana
authors: Concepció
authors: C
authors: Rovira
authors: Periannan
authors: P
authors: Kuppusamy
mesh_terms: D002713:Chlorine / Q000737:chemistry*; D045304:Cytochromes c / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D007962:Leukocytes / Q000737:chemistry / Q000201:enzymology; D008745:Methylation; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012996:Solutions; D013481:Superoxides / Q000737:chemistry*
chemical_list: D012996:Solutions; D013481:Superoxides; D002713:Chlorine; D045304:Cytochromes c; D006861:Hydrogen Peroxide