We studied the reaction kinetics of dismutation for superoxide ion by copper (Ⅱ) complex of macrocycllc dioxotetramine ligand 12- ( 4' - nitro )- benzyl-1,4,7,10- tetraazacy-clotridecane-11,13-dionato copper (Ⅱ)...We studied the reaction kinetics of dismutation for superoxide ion by copper (Ⅱ) complex of macrocycllc dioxotetramine ligand 12- ( 4' - nitro )- benzyl-1,4,7,10- tetraazacy-clotridecane-11,13-dionato copper (Ⅱ) by using pulse radiolysis. The rate constants of dismutation kcat's were measured to be 1. 78×106 mor-1 . L.s-1(at pH 7. 0) and 1. 06×106 mol-1. L. s-1(at pH 7. 8). The reaction mechanism is similar to that catalyzed by super-oxide dismutase.展开更多
The dismutation kinetics of superoxide anion by copper complex of 1,4,7,10-tetranza- cyctotridecane-11,13-dione was studied by pulse radiolysis.The dismutation rate constants at various pH and concentration of complex...The dismutation kinetics of superoxide anion by copper complex of 1,4,7,10-tetranza- cyctotridecane-11,13-dione was studied by pulse radiolysis.The dismutation rate constants at various pH and concentration of complex were obtained.展开更多
Salinity stress induces oxidative stress caused by reactive oxygen species （ROS）： superoxide radicals, hydrogen peroxide （H2O2） and hydroxyl radicals. Activities of both enzymatic and non-enzymatic components of ...Salinity stress induces oxidative stress caused by reactive oxygen species （ROS）： superoxide radicals, hydrogen peroxide （H2O2） and hydroxyl radicals. Activities of both enzymatic and non-enzymatic components of the antioxidant system and related growth parameters were studied in the roots of the salt tolerant rice variety FL478 and the sensitive variety IR29 in response to long term stress （12 d）induced by 50 mmol/L NaCI. The comparative study showed that FL478 maintained higher relative growth rate and lower Na＋/K＋ in the roots than IR29 due to a higher membrane stability index that effectively exclude Na＋. Lower TBARS （thiobarbituric acid reactive substance） content in FL478 roots indicated that its membrane was relatively unaffected by ROS despite high H2O2 content recorded under the salinity stress. Relatively higher superoxide dismutase activity along with a parallel increase in transcript level of superoxide dismutase （Os07g46990） in FL478 indicated that this protein might make a vital contribution to salt stress tolerance. Although the content of ascorbic acid remained unchanged in FL478, the activity of ascorbic peroxidases （APOXs） was reduced comparably in the both varieties. Transcriptomic data showed that a larger number of peroxidase genes were upregulated in FL478 compared to IR29 and several of which might provide engineering targets to improve rice salt tolerance.展开更多
Nearly monodisperse spherical amorphous Se colloids are prepared by the dismutation of Na_(2)SeSO_(3)solution at room temperature;by altering the pH of the solution,amorphous Se colloid spheres with sizes of about 120...Nearly monodisperse spherical amorphous Se colloids are prepared by the dismutation of Na_(2)SeSO_(3)solution at room temperature;by altering the pH of the solution,amorphous Se colloid spheres with sizes of about 120 nm,200 nm,300 nm,and 1μm can be obtained.Se@Ag2Se core/shell spheres are successfully synthesized by using the obtained amorphous Se(a-Se)spheres as templates,indicating the potential applications of these Se nanomaterials in serving as soft templates for other selenides.Meanwhile,selenium nanowires are obtained through a“solid-solution-solid”growth process by dispersing the prepared Se spheres in ethanol.This simple and environmentally benign approach may offer more opportunities in the synthesis and applications of nanocrystal materials.展开更多
The polarographic catalytic wave of oxygen reduction caused by mefenamic acid (MA) with redox properties was reported in this paper. The electrochemical process of the catalytic wave was proposed that the superoxide a...The polarographic catalytic wave of oxygen reduction caused by mefenamic acid (MA) with redox properties was reported in this paper. The electrochemical process of the catalytic wave was proposed that the superoxide anion O(?) was generated polarographically and the dismutation of the O(?) was catalyzed by MA to reproduce O_2 and H_2O_2. This explained chemically the scavenging of the O_2^- by MA im biomedical area. Based on the catalytic wave, a new method for the determination of MA by single-sweep polarography was developed.展开更多
文摘We studied the reaction kinetics of dismutation for superoxide ion by copper (Ⅱ) complex of macrocycllc dioxotetramine ligand 12- ( 4' - nitro )- benzyl-1,4,7,10- tetraazacy-clotridecane-11,13-dionato copper (Ⅱ) by using pulse radiolysis. The rate constants of dismutation kcat's were measured to be 1. 78×106 mor-1 . L.s-1(at pH 7. 0) and 1. 06×106 mol-1. L. s-1(at pH 7. 8). The reaction mechanism is similar to that catalyzed by super-oxide dismutase.
文摘The dismutation kinetics of superoxide anion by copper complex of 1,4,7,10-tetranza- cyctotridecane-11,13-dione was studied by pulse radiolysis.The dismutation rate constants at various pH and concentration of complex were obtained.
基金funded by Asian Development Bank’s-Distance Education Modernization Programme at the Open University of Sri Lanka to Prasad SENADHEERA
文摘Salinity stress induces oxidative stress caused by reactive oxygen species （ROS）： superoxide radicals, hydrogen peroxide （H2O2） and hydroxyl radicals. Activities of both enzymatic and non-enzymatic components of the antioxidant system and related growth parameters were studied in the roots of the salt tolerant rice variety FL478 and the sensitive variety IR29 in response to long term stress （12 d）induced by 50 mmol/L NaCI. The comparative study showed that FL478 maintained higher relative growth rate and lower Na＋/K＋ in the roots than IR29 due to a higher membrane stability index that effectively exclude Na＋. Lower TBARS （thiobarbituric acid reactive substance） content in FL478 roots indicated that its membrane was relatively unaffected by ROS despite high H2O2 content recorded under the salinity stress. Relatively higher superoxide dismutase activity along with a parallel increase in transcript level of superoxide dismutase （Os07g46990） in FL478 indicated that this protein might make a vital contribution to salt stress tolerance. Although the content of ascorbic acid remained unchanged in FL478, the activity of ascorbic peroxidases （APOXs） was reduced comparably in the both varieties. Transcriptomic data showed that a larger number of peroxidase genes were upregulated in FL478 compared to IR29 and several of which might provide engineering targets to improve rice salt tolerance.
基金This work was supported by NSFC(90606006)the State Key Project of Fundamental Research for Nanoscience and Nanotechnology(2006CB932300)the Key Grant Project of Chinese Ministry of Education.(NO.306020).
文摘Nearly monodisperse spherical amorphous Se colloids are prepared by the dismutation of Na_(2)SeSO_(3)solution at room temperature;by altering the pH of the solution,amorphous Se colloid spheres with sizes of about 120 nm,200 nm,300 nm,and 1μm can be obtained.Se@Ag2Se core/shell spheres are successfully synthesized by using the obtained amorphous Se(a-Se)spheres as templates,indicating the potential applications of these Se nanomaterials in serving as soft templates for other selenides.Meanwhile,selenium nanowires are obtained through a“solid-solution-solid”growth process by dispersing the prepared Se spheres in ethanol.This simple and environmentally benign approach may offer more opportunities in the synthesis and applications of nanocrystal materials.
文摘The polarographic catalytic wave of oxygen reduction caused by mefenamic acid (MA) with redox properties was reported in this paper. The electrochemical process of the catalytic wave was proposed that the superoxide anion O(?) was generated polarographically and the dismutation of the O(?) was catalyzed by MA to reproduce O_2 and H_2O_2. This explained chemically the scavenging of the O_2^- by MA im biomedical area. Based on the catalytic wave, a new method for the determination of MA by single-sweep polarography was developed.
