Three tridentate imine ligands containing N2S donors were synthesized via Schiff condensation between derivatives of both amino triazine and 2-carbonyl pyridine.The reaction of these ligands with CuCl2 in a molar rati...Three tridentate imine ligands containing N2S donors were synthesized via Schiff condensation between derivatives of both amino triazine and 2-carbonyl pyridine.The reaction of these ligands with CuCl2 in a molar ratio of 1:1 provides three Cu(II) complexes with the general formula [CuLn·Cl_(2)].Analytical,electrical,magnetic,and spectroscopic studies were used to assign the molecular formulae of these metallic chelates.Density function theory (DFT) calculations confirmed the structural analysis results obtained from spectroscopic studies.The various characterization techniques used demonstrated the penta-coordinated slightly distorted square pyramidal structure for the present Cu(II) complexes 1,2,and 3.Measurements of cyclic voltammetry were done in methanol to define the electrochemical behavior of the current Cu(II) complexes.The biomimetics of catechol oxidase (C.O.);phenoxazinone synthase (PHS) have been studied in the aerobic oxidation of some phenolic substrates,such as 3,5-di-tert-butylcatechol (3,5-DTBCH2);ortho-aminophenol (o-APH3).The three candidate oxidase mimetics showed promising activity in the order 3 > 1 > 2.The catalytic activity related to the structural properties of existing oxidase mimetics was discussed.The driving force (-ΔG°) controlling the redox reactions of the present biomolecules was calculated from the redox data of Cu(II) complexes 1,2,and 3.The potential catalytic reaction pathway for the oxidation of the studied phenolic substrates was discussed.展开更多
Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxi...Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.展开更多
基金the Deanship of Graduate Studies and Scientific Research,Taif University for funding this work.
文摘Three tridentate imine ligands containing N2S donors were synthesized via Schiff condensation between derivatives of both amino triazine and 2-carbonyl pyridine.The reaction of these ligands with CuCl2 in a molar ratio of 1:1 provides three Cu(II) complexes with the general formula [CuLn·Cl_(2)].Analytical,electrical,magnetic,and spectroscopic studies were used to assign the molecular formulae of these metallic chelates.Density function theory (DFT) calculations confirmed the structural analysis results obtained from spectroscopic studies.The various characterization techniques used demonstrated the penta-coordinated slightly distorted square pyramidal structure for the present Cu(II) complexes 1,2,and 3.Measurements of cyclic voltammetry were done in methanol to define the electrochemical behavior of the current Cu(II) complexes.The biomimetics of catechol oxidase (C.O.);phenoxazinone synthase (PHS) have been studied in the aerobic oxidation of some phenolic substrates,such as 3,5-di-tert-butylcatechol (3,5-DTBCH2);ortho-aminophenol (o-APH3).The three candidate oxidase mimetics showed promising activity in the order 3 > 1 > 2.The catalytic activity related to the structural properties of existing oxidase mimetics was discussed.The driving force (-ΔG°) controlling the redox reactions of the present biomolecules was calculated from the redox data of Cu(II) complexes 1,2,and 3.The potential catalytic reaction pathway for the oxidation of the studied phenolic substrates was discussed.
文摘Polyamines （PA）, polyamine oxidases, copper amine oxidases, and nitric oxide （NO） play important roles in physiology and stress responses in plants. NO biosynthesis as a result of catabolism of PA by polyamine oxidases and copper amine oxidases may explain in part PA-mediated responses. Involvement of a copper amine oxidase gene, COPPER AMINE OXIDASEI （CuAO1）, of Arabidopsis was tested for its role in stress responses using the knockouts cuao1-1 and cuaol-2. PA-induced and ABA-induced NO production investigated bY fluorometry and fluorescence microscopy showed that the cuaol-1 and cuaol-2 are impaired in NO production, suggesting a function of CuAO1 in PA and ABA-mediated NO production. Furthermore, we found a PA-dependent increase in protein S-nitrosylation. The addition of PA and ABA also resulted in H2O2 increases, cuao1-1 and cuao1-2 showed less sensitivity to exogenous ABA supplementation during germination, seedling establishment, and root growth inhibition as compared to wild-type. In response to ABA treatment, expression levels of the stress-responsive genes RD29A and ADH1 were significantly lower in the knockouts. These observations characterize cuao1-1 and cuao1-2 as ABA-insensitive mutants. Taken together, our findings extend the ABA signal transduction network to include CuAO1 as one potential contributor to enhanced NO production by ABA.
