1,721,006 research outputs found
Effects of hypotaurine on carbonate radical anion and nitrogen dioxide radical generated by peroxidase activity of Cu,Zn-superoxide dismutase
No full textCysteine sulfinate (CSA) and hypotaurine are recognized as key intermediates in the metabolic pathway leading from cysteine to taurine. The oxidation of sulfinic group to the respective sulfonate is a crucial point for generation of taurine in mammalian tissues. The mechanism of sulfinic group oxidation could not be related to specific enzymatic activities. However, oxidizing agents, such as hydroxyl radical, photochemically generated singlet oxygen and peroxynitrite have been reported to accomplish such oxidation in good yield.
Carbonate radical anion (CO3 radical) is receiving increasing attention as important mediator of biological processes and is a potent one-electron oxidant that is able to oxidize a variety of biotargets. Nitrogen dioxide radical (NO2) is well known as a reactive species capable to initiate both oxidation and nitration reactions. The pathogenic role of radical NO2 has been related mostly to the increased level of nitrated proteins detected under many disease
"Spontaneous" endoreduplication in Chinese hamster cell cultures. I: Effect of growth conditions.
No full textSome new details of the copper-hydrogen peroxide interaction
No full textThe addition of neocuproine (NC) or bathocuproine-disulphonate at the end of the autooxidation of Cu-I in phosphate buffer, pH 7.4, regenerates almost entirely the O-2 consumed. Other chelating agents assayed, including o-phenanthroline, cannot replace NC in promoting the O-2 formation. O-2 is also produced by adding NC to a mixture of Cu-II and H2O2 Concomitant with the O-2 evolution, the typical absorbance of the (NC)(2)Cu-I complex appears to account for the complete reduction of Cu-II to Cu-I. It is concluded that the addition of H2O2 with Cu-II produces the equilibrium Cu-II(O2H)(-) (CdO2H)-O-I.. Addition of NC shifts the equilibrium to the right side by binding CuI. The released O-2(.-) then reacts with the remaining Cu-II yielding, in the presence of NC, the net reaction of 4 NC + 2 Cu-II + H2O2 --> 2 (NC)(2)Cu-I + O-2 + 2 H+. O-2 is also released in the absence of added NC provided the H2O2 concentration is increased. In these conditions the Cu-II(O2H)(-) complex undergoes other reactions leading to the copper-catalysed decomposition of H2O2. (C) 1997 Academic Press
Preparation and properties of the decarboxylated dimer of aminoethylcysteine ketimine
No full textA simple procedure for the preparation of the aminoethylcysteine ketimine decarboxylated dimer in gram amounts is presented and some relevant properties of the product are reported
Regulation of polymorphonuclear leukocyte function by nitroenkephalin, a nitrated biomolecule formed by activated human neutrophils.
No full textThe protective effect of hypotaurine and cysteine sulphinic acid on peroxynitrite-mediated oxidative reactions
No full textThe protective activity of hypotaurine (HTAU) and cysteine sulphinic acid (CSA) on peroxynitrite-mediated oxidative damage has been assessed by monitoring different target molecules, i.e. tyrosine, dihydrorhodamine-123 (DHR) and glutathione (GSH). The inhibition of tyrosine oxidation exerted by HTAU and CSA both in the presence and the absence of bicarbonate can be ascribed to their ability to scavenge hydroxyl ((OH)-O-center dot) and carbonate (CO3 center dot-) radicals. HTAU and CSA also reduce tyrosyl radicals, suggesting that this repair function of sulphinates might operate as an additional inhibiting mechanism of tyrosine oxidation. In the peroxynitrite-dependent oxidation of DHR, the inhibitory effect of HTAU was lower than that of CSA. Moreover, while HTAU and CSA competitively inhibited the direct oxidation of GSH by peroxynitrite, HTAU was again poorly effective against the oxidation of GSH mediated by peroxynitrite-derived radicals. The possible involvement of secondary reactions, which could explain the difference in antioxidant activity of HTAU and CSA, is discussed
Antioxidant properties of the decarboxylated dimer of aminoethylcysteine ketimine: assessment of its ability to scavenge peroxynitrite.
No full textThe natural sulfur compound aminoethylcysteine ketimine decarboxylated dimer (AECK dimer) has been investigated for its ability to act as peroxynitrite scavenger. It has been found that the product efficiently protects against the nitration of tyrosine and the inactivation of oz-antiproteinase by peroxynitrite. The tyrosine nitration can be completely prevented by 100 mu M AECK dimer which appears as effective as the antioxidants glutathione and N-acetylcysteine. The AECK dimer was also found to limit surface charge alteration of low density lipoprotein induced by peroxynitrite. These findings indicate that the AECK dimer is a strong protective agent against peroxynitrite damage and that it could play an important role in the defence against oxidative stress in human diseases
Aminoethylcysteine ketimine decarboxylated dimer inhibits mitochondrial respiration by impairing electron transport at complex I level.
No full textThe product of the spontaneous dimerization and decarboxylation of aminoethylcysteine ketimine (simply named the dimer in this note) has been investigated for a possible biochemical activity. It has been found that the dimer inhibits the ADP-dependent oxidation of NAD+-linked substrates in rat liver mitochondria and electron transport from NADH to O2 in bovine heart submitochondrial particles (SMP). Oxidation of succinate by SMP is not impaired by concentrations of the dimer inhibiting almost totally NADH oxidation. Furthermore, the dimer did not affect the rotenone-insensitive electron transfer from NADH to menadione. These results give a preliminary indication suggesting that the dimer inhibits electron flow from NADH dehydrogenase to ubiquinone at or near the rotenone binding site(s). The dimer inhibition falls in the same range exibited by some neurotoxins which are known to interact with the rotenone binding site
INFLUENCE OF DIET ON CYSTATHIONINE KETIMINE AND LANTHIONINE KETIMINE CONTENT IN HUMAN URINE
No full text[No abstract available
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