The interaction between apoCopC and cupric was investigated by fluorescence spectra, in phosphate (20 mmol/L) buffer at pH 6.0. Results suggest that the environ- ment is measured to be hydrophobic completely around tr...The interaction between apoCopC and cupric was investigated by fluorescence spectra, in phosphate (20 mmol/L) buffer at pH 6.0. Results suggest that the environ- ment is measured to be hydrophobic completely around tryptophan (83). At the same time, apoCopC fluorescence at 320 nm was significantly quenched with the addition of cu- pric and the 1:1 stoichiometric ratio of apoCopC to cupric was confirmed by fluorescence. In addition, the conditional binding constants were calculated to be KCu-Copc = (1.8±0.58)× 1013 mol?1 L on the basis of the results of fluorescence titra- tion curves. The apoCopC has the ability to bind specifically cupric ion.展开更多
The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer （10 mmol·L^-1） at pH 7.4. The results suggest that mercur...The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer （10 mmol·L^-1） at pH 7.4. The results suggest that mercuric ion can bind to C- and N-terminal binding sites of apoCopC, and the conditional binding constants were calculated to be kN=（6.79± 1.12）× 10^6 mol^-1·L and kc=（3.06±0.05）× 10^5 mol^-1·L. Using urea as a chemical agent, the conformational stabilities of apoCopC and HgN^2＋ -CopC-Hgc^2＋ were monitored by fluorescence spectrum in Hepes buffer （50 mmol·L^-1） at pH 7.4. The free energy of stabilization is （14.69±0.85） and （16.66±0.55） kJ.mol^-1, respectively. HgN^2＋ -CopC-Hgc^2＋ is more stable than apoCopC.展开更多
The CopC protein from pseudomonas syringae pathovar tomato is expressed as one of four proteins encoded by the operon CopABCD that is responsible for copper resistance. And there are one trypto-phan (83), one tyrosine...The CopC protein from pseudomonas syringae pathovar tomato is expressed as one of four proteins encoded by the operon CopABCD that is responsible for copper resistance. And there are one trypto-phan (83), one tyrosine (79), and three phenylalanines (35, 43, 99) in apoCopC. The fluorescence peak of apoCopC is located near 320 nm, and the peak shifts toward 353 nm in the presence of 10 mmol·L^(-1) urea with excitation at 280 nm. Using urea as a chemical agent, the conformational stabilities of apoCopC and Cu_N^(2+) -CopC were monitored by fluorescence spectrum in 20 mmol·L^(-1) phosphate buffer and 100 mmol·L^(-1) sodium chloride at pH 6.0. The free energy of stabilization for apoCopC and Cu_N^(2+)-CopC is 16.29±0.65 kJ·mol^(-1) and 26.26±0.35 kJ·mol^(-1), respectively. The distance between the tryptophan residue and the Cu^(2+) in Cu_N^(2+) -CopC has been studied by observing Frster type nonradia-tive energy transfer. And it is calculated to be 11.6 .展开更多
基金supported by the National Natural Science Foundation of China(Grant No.20371031)the Natural Science Foundation of Shanxi Province(Grant No.20031017).
文摘The interaction between apoCopC and cupric was investigated by fluorescence spectra, in phosphate (20 mmol/L) buffer at pH 6.0. Results suggest that the environ- ment is measured to be hydrophobic completely around tryptophan (83). At the same time, apoCopC fluorescence at 320 nm was significantly quenched with the addition of cu- pric and the 1:1 stoichiometric ratio of apoCopC to cupric was confirmed by fluorescence. In addition, the conditional binding constants were calculated to be KCu-Copc = (1.8±0.58)× 1013 mol?1 L on the basis of the results of fluorescence titra- tion curves. The apoCopC has the ability to bind specifically cupric ion.
基金Project supported by the National Natural Science Foundation of China （No. 20371031） and the Natural Science Foundation of Shanxi Province （No. 20031017）.
文摘The interaction between mercuric ion and apoCopC in the absence or presence of cupric ion was investigated through difference UV spectra in Hepes buffer （10 mmol·L^-1） at pH 7.4. The results suggest that mercuric ion can bind to C- and N-terminal binding sites of apoCopC, and the conditional binding constants were calculated to be kN=（6.79± 1.12）× 10^6 mol^-1·L and kc=（3.06±0.05）× 10^5 mol^-1·L. Using urea as a chemical agent, the conformational stabilities of apoCopC and HgN^2＋ -CopC-Hgc^2＋ were monitored by fluorescence spectrum in Hepes buffer （50 mmol·L^-1） at pH 7.4. The free energy of stabilization is （14.69±0.85） and （16.66±0.55） kJ.mol^-1, respectively. HgN^2＋ -CopC-Hgc^2＋ is more stable than apoCopC.
基金Supported by the National Natural Science Foundation of China (Grant No.20371031)the Natural Science Foundation of Shanxi Province (Grant No.20031017)
文摘The CopC protein from pseudomonas syringae pathovar tomato is expressed as one of four proteins encoded by the operon CopABCD that is responsible for copper resistance. And there are one trypto-phan (83), one tyrosine (79), and three phenylalanines (35, 43, 99) in apoCopC. The fluorescence peak of apoCopC is located near 320 nm, and the peak shifts toward 353 nm in the presence of 10 mmol·L^(-1) urea with excitation at 280 nm. Using urea as a chemical agent, the conformational stabilities of apoCopC and Cu_N^(2+) -CopC were monitored by fluorescence spectrum in 20 mmol·L^(-1) phosphate buffer and 100 mmol·L^(-1) sodium chloride at pH 6.0. The free energy of stabilization for apoCopC and Cu_N^(2+)-CopC is 16.29±0.65 kJ·mol^(-1) and 26.26±0.35 kJ·mol^(-1), respectively. The distance between the tryptophan residue and the Cu^(2+) in Cu_N^(2+) -CopC has been studied by observing Frster type nonradia-tive energy transfer. And it is calculated to be 11.6 .
