Objective:To investigate the effect of oxidized transitional metal（ferric and cupric） ions on the amino acids.Methods:25 mmol/L hydroxyproline and 25 mmol/L histidine were incubated with 50μL Fe<sup>3+</su...Objective:To investigate the effect of oxidized transitional metal（ferric and cupric） ions on the amino acids.Methods:25 mmol/L hydroxyproline and 25 mmol/L histidine were incubated with 50μL Fe<sup>3+</sup> and Cu<sup>2+</sup> ions at pH 7.4 and 37℃for 30 mins in separate test tubes.Then 500μL of 1% thiobarbituricacid（TBA） was added to the incubated amino acids followed by addition of 500μL of glacial acetic acid.The resultant mixture was vortexed and heated at 100℃for 30 min.Absorbance readings were noted after cooling to room temperature.The experiment was repeated in the presence of various reagents,like hydroxyl radical scavengers,antioxidant enzymes,and reducing agents and metal ion chelators.Results:The pink chromogen formed with the absorbance maxima at 524 nm,AND shifted to 560 nm in alkaline pH.The absorbance was expressed as TBAadduct in MDA units.The TBA-adduct decreased in the presence of reducing agents and metal ion chelators.Antioxidant enzymes and hydroxyl radical scavengers did not show any effect. Conclusion:Transitional metal ions in their oxidized state showed significant damage to amino acids,hydroxyproline and histidine.The results indicate the possible role played by high-valent oxo-iron species,ferryl and perferry radicals in damaging biomolecules.展开更多
During the oxidative degradation of nonbiodegradable Malachite green (MG) by means of H2O2 /FeIIIR (iron supported on ion-exchage resin) in a dynamic column,the binding energy of the Fe(2p3/2) region for XPS spectra w...During the oxidative degradation of nonbiodegradable Malachite green (MG) by means of H2O2 /FeIIIR (iron supported on ion-exchage resin) in a dynamic column,the binding energy of the Fe(2p3/2) region for XPS spectra was found to be different between the top layer and the bottom layer in this column. Based on the data from XPS spectra and DMPO-OH·signal by EPR spectra,it is shown that the formation of ferryl (IV) is the key step for the oxidation of MG. The ferryl (IV) species can oxidize MG,and its redox potential is about 0. 739 - 0. 803 V measured by cyclic voltammograms (CV) . The catalytic capability of ferryl (IV) species was also evaluated,and it is found that it can promote the decomposition of H2O2 more efficiently than ferric iron. The removal rate of MG mainly depends on the adsorption of catalyst. Both ferryl (IV) and HO·radicals are the reactive species in the system. The oxidation of HO·is only a small part of the overall removal rate. Based on the obtained results,a possible mechanism for a resin-supported Fenton-like oxidation reaction is proposed.展开更多
文摘Objective:To investigate the effect of oxidized transitional metal（ferric and cupric） ions on the amino acids.Methods:25 mmol/L hydroxyproline and 25 mmol/L histidine were incubated with 50μL Fe<sup>3+</sup> and Cu<sup>2+</sup> ions at pH 7.4 and 37℃for 30 mins in separate test tubes.Then 500μL of 1% thiobarbituricacid（TBA） was added to the incubated amino acids followed by addition of 500μL of glacial acetic acid.The resultant mixture was vortexed and heated at 100℃for 30 min.Absorbance readings were noted after cooling to room temperature.The experiment was repeated in the presence of various reagents,like hydroxyl radical scavengers,antioxidant enzymes,and reducing agents and metal ion chelators.Results:The pink chromogen formed with the absorbance maxima at 524 nm,AND shifted to 560 nm in alkaline pH.The absorbance was expressed as TBAadduct in MDA units.The TBA-adduct decreased in the presence of reducing agents and metal ion chelators.Antioxidant enzymes and hydroxyl radical scavengers did not show any effect. Conclusion:Transitional metal ions in their oxidized state showed significant damage to amino acids,hydroxyproline and histidine.The results indicate the possible role played by high-valent oxo-iron species,ferryl and perferry radicals in damaging biomolecules.
基金Sponsored by the National High Technology Research and Development Program of China(863 Program) (Grant No.2006AA06Z306)the Natural Science Foundation of China under the Scheme of Innovation Group Fund
文摘During the oxidative degradation of nonbiodegradable Malachite green (MG) by means of H2O2 /FeIIIR (iron supported on ion-exchage resin) in a dynamic column,the binding energy of the Fe(2p3/2) region for XPS spectra was found to be different between the top layer and the bottom layer in this column. Based on the data from XPS spectra and DMPO-OH·signal by EPR spectra,it is shown that the formation of ferryl (IV) is the key step for the oxidation of MG. The ferryl (IV) species can oxidize MG,and its redox potential is about 0. 739 - 0. 803 V measured by cyclic voltammograms (CV) . The catalytic capability of ferryl (IV) species was also evaluated,and it is found that it can promote the decomposition of H2O2 more efficiently than ferric iron. The removal rate of MG mainly depends on the adsorption of catalyst. Both ferryl (IV) and HO·radicals are the reactive species in the system. The oxidation of HO·is only a small part of the overall removal rate. Based on the obtained results,a possible mechanism for a resin-supported Fenton-like oxidation reaction is proposed.
