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1.
FEBS Lett ; 230(1-2): 155-8, 1988 Mar 28.
Article in English | MEDLINE | ID: mdl-2832212

ABSTRACT

In the sera and synovial fluid of patients with rheumatoid arthritis, part of the IgG fraction is found in an aggregated and fluorescent form. Oxygen-free radicals have been implicated in this denaturation, although the precise radical species responsible is unknown. In this work, oxygen-free radicals generated radiolytically were allowed to attack polyclonal IgG in solution. OH radicals induced aggregation of the monomer and a new fluorescence appeared in the visible region (Ex 360 nm, Em 454 nm). The superoxide radical anion was found to be inert in both these respects, whilst peroxy radicals induced autofluorescence without concomitant aggregation. The results suggest that OH.and/or peroxy radical attack may be an in vivo mechanism for IgG denaturation.


Subject(s)
Hydroxides/pharmacology , Immunoglobulin G , Peroxides/pharmacology , Superoxides/pharmacology , Chromatography, Gel , Chromatography, High Pressure Liquid , Fluorescence , Free Radicals , Gamma Rays , Humans , Hydroxyl Radical , Macromolecular Substances , Spectrometry, Fluorescence
2.
Biochem J ; 246(3): 725-9, 1987 Sep 15.
Article in English | MEDLINE | ID: mdl-2825650

ABSTRACT

In neutral solutions, desferrioxamine (Desferal) can react with the superoxide free radical, O2.- (possibly through its protonated form HO2.), to form a relatively stable nitroxide free radical, which can have a half-life of approx. 10 min at room temperature. The formation of the radical can be largely prevented by the presence of superoxide dismutase. The radical reacts rapidly with cysteine, methionine, glutathione, vitamin C and a water-soluble derivative of vitamin E. It also reacts rapidly with alcohol dehydrogenase, causing a loss of enzyme activity. The implications of these findings for mechanistic free-radical biochemistry and iron-chelation therapy could be considerable.


Subject(s)
Deferoxamine/pharmacology , Nitrogen Oxides/metabolism , Superoxides/metabolism , Alcohol Dehydrogenase/antagonists & inhibitors , Antioxidants/pharmacology , Electron Spin Resonance Spectroscopy , Free Radicals
3.
Philos Trans R Soc Lond B Biol Sci ; 311(1152): 545-63, 1985 Dec 17.
Article in English | MEDLINE | ID: mdl-2869516

ABSTRACT

The reactions of organic free radicals, acting as either reductants or oxidants, have been studied by pulse radiolysis in neutral aqueous solution at room temperature. Manyhydroxyl-substituted aliphatic carbon-centred radicals and one-electron adducts have been shown to be good one-electron reductants, while several oxygen-, sulphur- and nitrogen- (but not carbon-) centred free radicals have been shown to be good one-electron oxidants. Several carbon-centred radicals can be reduced rapidly by hydrogen transfer, from undissociated thiol compounds which can thus act as catalysts facilitating the overall reduction of a carbon-centred radical by an electron-donating molecule. Kinetic considerations influenced by the one-electron redox potentials of the radical-molecule couples involved, determine whether a particular reaction predominates. In this paper examples of such reactions, involving a water-soluble derivative of vitamin E (Trolox C) and the coenzyme NADH, are described, together with studies showing (a) that even in complex multi-solute systems some organic peroxy radicals can inactiviate alcohol dehydrogenase under conditions where the superoxide radical does not, and (b) the superoxide radical can be damaging if urate is also present, and this damage can be reduced by the presence of superoxide dismutase.


Subject(s)
Proteins/radiation effects , Alcohol Dehydrogenase , Alcohol Oxidoreductases , Free Radicals , Hydroxides , Iron , Muramidase/radiation effects , NAD , Oxidation-Reduction , Peroxides , Sulfhydryl Compounds , Superoxides , Uric Acid
4.
Br J Radiol ; 58(687): 251-6, 1985 Mar.
Article in English | MEDLINE | ID: mdl-2933117

ABSTRACT

In vitro studies have shown that in the presence of the DNA base thymine, the enzyme alcohol dehydrogenase can be extensively damaged by exposure to only 1 gray of cobalt-60 gamma radiation. When irradiated solutions are purged with oxygen-free nitrogen or contain the enzyme superoxide dismutase or various antioxidants, the extent of inactivation of the dehydrogenase is considerably reduced. Peroxy free radicals are considered to be responsible for the inactivation and cysteine and methionine residues are considered the most likely sites of initial damage. The results presented, with those obtained with ADP and urate instead of thymine and with various amino acids and foreign compounds, are discussed in the light of previous statements concerning the relevance of enzyme damage in radiobiology and the role of oxygen free radicals in tissue injury generally.


Subject(s)
Alcohol Oxidoreductases/radiation effects , Radiation-Protective Agents , Radiation-Sensitizing Agents , Alcohol Dehydrogenase , Antioxidants , Cobalt Radioisotopes , Dose-Response Relationship, Radiation , Free Radicals , Gamma Rays , Oxygen , Superoxide Dismutase
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