The solubility of nonivamide in dimethyl sulfoxide, methanol, acetone, ethyl acetate, methyl tert-butyl ether, acetonitrile, n-hexane and water over the temperature range of 293.2 K to 323.2 K was measured. The result...The solubility of nonivamide in dimethyl sulfoxide, methanol, acetone, ethyl acetate, methyl tert-butyl ether, acetonitrile, n-hexane and water over the temperature range of 293.2 K to 323.2 K was measured. The results reveal that the solubility of nonivamide is greatly influenced by the hydrogen-bond basicity of solvent and increases with temperature. The experimental data were correlated with the modified Apelblat equation. The dissolution enthalpy and entropy of nonivamide in different solvents were obtained from the correlation of lnx with 1/T using the van't Hoff equation. The calculated nonivamide solubility is in good agreement with experimental data for most of the solvents.展开更多
Thermodynamic properties of complexes of Con ?go Red (CR) dye with amyloid ? (A?) peptides were studied by both absorption spectroscopy and isothermal titration calorimetry (ITC). Based on the absorption spectrum for ...Thermodynamic properties of complexes of Con ?go Red (CR) dye with amyloid ? (A?) peptides were studied by both absorption spectroscopy and isothermal titration calorimetry (ITC). Based on the absorption spectrum for the formation of CRAβ complexes in phosphate buffered saline solution (pH 7.4), van’t Hoff plots over a temperature range of 10oC to 70oC were created for CRAβ140, Aβ1228, and Aβ142. The plot for CR Aβ1228 complex showed a relatively linear feature within the given temperature range with ?H = –10.1 ?0.6 kJ/mol and ?S = + 0.128 ? 0.002 kJ/(mol K). However, the plot for CRAβ140 and CRAβ142 complexes exhibited two distinct linear regions with opposite slopes centered at a specific temperature, Ts, which was 54.7 ? 0.2℃ and 34.8 ? 0.2℃, respectively. The ITC experiments conducted at 25℃in water exhibited quite a different situation from the above mentioned spectroscopic approach. The ITC studies yielded a ?H of –85.3 ? 0.2 kJ/mol for the CRAβ1228 complex with negative entropy change –0.152 kJ/mol K). For CRAβ140, the ITC studies indicated the presence of two binding sites with ?H1 = –81.8 ? 0.3 kJ/mol and ?H2 = –119.5 ? 0.2 kJ/mol with K1 = 5.5 ? 0.7 ? 106 M1 and K2 = 6.9 ? 2.4 ? 108 M1, respectively. These binding constants are consistent with the model suggested by several studies. Both binding sites showed negative entropy changes suggesting that the formation of the complex is enthalpically driven. The disagreement in thermochemical values between two different methods confirmed that the enthalpy and entropy are heavily dependent on temperature and buffer/salt environment, and may involve inherently different reaction paths.展开更多
A novel approach has been developed to determine the amount of residual water in human erythrocyte at room temperature by electronic particle counter. Nacl solutions of 13 osmolalities were prepared and the equilibriu...A novel approach has been developed to determine the amount of residual water in human erythrocyte at room temperature by electronic particle counter. Nacl solutions of 13 osmolalities were prepared and the equilibrium cell volumes in which were measured one by one.The isotonic volume, V0, was obtained under the isotonic condition. The mean RBC volumes of 5 donors at each osmolality were fitted according to Boyle van’t Hoff relationship, and the osmotically inactive volume, Vb, of erythrocyte was then determined. The results show that Vb50% V0. More importantly, the final cell volume with regard to the solution of the highest concentration found to be kept at about 0.5 V0. The difference between these two volumes is unconspicuous. According to the published data that non-water volume of human erythrocyte is about 28.3% of its isotonic volume, residual water of human erythrocyte can be gained by subtracting V dry from Vf, that is V rw =21.7% V0. Then it was concluded that the residual water of human lays in 2 states, one is bound water, and the other is free water.展开更多
基金Supported by the National Natural Science Foundation of China(20936005,21222601)the National High Technology Research and Development Program of China(2012AA040211)
文摘The solubility of nonivamide in dimethyl sulfoxide, methanol, acetone, ethyl acetate, methyl tert-butyl ether, acetonitrile, n-hexane and water over the temperature range of 293.2 K to 323.2 K was measured. The results reveal that the solubility of nonivamide is greatly influenced by the hydrogen-bond basicity of solvent and increases with temperature. The experimental data were correlated with the modified Apelblat equation. The dissolution enthalpy and entropy of nonivamide in different solvents were obtained from the correlation of lnx with 1/T using the van't Hoff equation. The calculated nonivamide solubility is in good agreement with experimental data for most of the solvents.
文摘Thermodynamic properties of complexes of Con ?go Red (CR) dye with amyloid ? (A?) peptides were studied by both absorption spectroscopy and isothermal titration calorimetry (ITC). Based on the absorption spectrum for the formation of CRAβ complexes in phosphate buffered saline solution (pH 7.4), van’t Hoff plots over a temperature range of 10oC to 70oC were created for CRAβ140, Aβ1228, and Aβ142. The plot for CR Aβ1228 complex showed a relatively linear feature within the given temperature range with ?H = –10.1 ?0.6 kJ/mol and ?S = + 0.128 ? 0.002 kJ/(mol K). However, the plot for CRAβ140 and CRAβ142 complexes exhibited two distinct linear regions with opposite slopes centered at a specific temperature, Ts, which was 54.7 ? 0.2℃ and 34.8 ? 0.2℃, respectively. The ITC experiments conducted at 25℃in water exhibited quite a different situation from the above mentioned spectroscopic approach. The ITC studies yielded a ?H of –85.3 ? 0.2 kJ/mol for the CRAβ1228 complex with negative entropy change –0.152 kJ/mol K). For CRAβ140, the ITC studies indicated the presence of two binding sites with ?H1 = –81.8 ? 0.3 kJ/mol and ?H2 = –119.5 ? 0.2 kJ/mol with K1 = 5.5 ? 0.7 ? 106 M1 and K2 = 6.9 ? 2.4 ? 108 M1, respectively. These binding constants are consistent with the model suggested by several studies. Both binding sites showed negative entropy changes suggesting that the formation of the complex is enthalpically driven. The disagreement in thermochemical values between two different methods confirmed that the enthalpy and entropy are heavily dependent on temperature and buffer/salt environment, and may involve inherently different reaction paths.
基金This research is supported by NSFC(5 0 10 6 0 16 ) ,NSF of Anhui Province(0 0 0 4 75 2 0 ,0 30 4 3717)
文摘A novel approach has been developed to determine the amount of residual water in human erythrocyte at room temperature by electronic particle counter. Nacl solutions of 13 osmolalities were prepared and the equilibrium cell volumes in which were measured one by one.The isotonic volume, V0, was obtained under the isotonic condition. The mean RBC volumes of 5 donors at each osmolality were fitted according to Boyle van’t Hoff relationship, and the osmotically inactive volume, Vb, of erythrocyte was then determined. The results show that Vb50% V0. More importantly, the final cell volume with regard to the solution of the highest concentration found to be kept at about 0.5 V0. The difference between these two volumes is unconspicuous. According to the published data that non-water volume of human erythrocyte is about 28.3% of its isotonic volume, residual water of human erythrocyte can be gained by subtracting V dry from Vf, that is V rw =21.7% V0. Then it was concluded that the residual water of human lays in 2 states, one is bound water, and the other is free water.
