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酰胺是肽的基本结构单元, 而且在蛋白质的二级结构中与酰胺联系的氢键对蛋白质的稳定起着十分重要的作用. 作为蛋白质模型化合物热力学性质研究的一部分, 报道了甲酰胺在乙二醇水溶液中的稀释焓. 相似文献
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The effect of pH on the dilution enthalpies of D-p-hydroxyphenylglycine in phosphate buffer solutions has been investigated by isothermal titration microcalorimetry at 298.15 K. The corresponding homogeneous enthalpic interaction coefficients have been calculated according to the excess enthalpy concept. The results show that the enthalpies of dilution of D-p-hydroxyphenylglycine in phosphate buffer solutions at different pH are all positive. The overall trend is that enthalpies of dilution become more positive with an increase of pH, but there is a minimum of the enthalpy of dilution at pH = 7.0. The enthalpic pair interaction coefficients, h
2, all have negative values. The results are interpreted from the point of view of solute-solute and solute-solvent interactions involved in the solvent effects. 相似文献
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The enthalpy changes, entropy changes and equilibrium constants of coordination reactions of 18-crown-6 with the alkali ions Na+ and K+ at 298.15K were measured by using RD-496 microcalorimeter with methanol, ethanol, n-propanol and n-butanol as solvents respectively. The results indicated that the enthalpy changes △rHm, entropy changes △rSm, and the stability of the complexes are closely related with the polarity of the solvents, and the order of the stability is ethanol>methanol>n-propanol>n-butanol>H2O for the same complex in the solvents investigated. The stability order was reasonably explained by relating the stability constants of the complexes with the dielectric constants of these solvents, and by using the model of solvated-desolvated ions and ion pair in the coordination reactions. 相似文献
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采用在多孔氧化铝支撑体上预涂纳米丝光沸石晶种,再用水热晶化的方法制备丝光沸石复合膜.系统考察了反应母液陈化、碱度、盐以及反应温度等因素对丝光沸石晶体在预涂晶种支撑体上成膜化过程的影响.研究发现,膜表面晶体间空隙随反应母液陈化时间的增加而略有增大;高碱度的反应母液不利于连续丝光沸石复合膜的形成;反应母液中盐的浓度对丝光沸石晶体沿各个轴方向上的生长速率有不同程度的影响,膜表面晶体间空隙随盐浓度的增加而增大;晶化温度过高,容易形成细棒状晶体,导致晶体间空隙增大. 相似文献
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根据傅立叶定律径向系统的一维传热模型结合Tian's方程建立了一套高温流动型热量计,用于吸热型碳氢燃料的热沉测定和引发剂筛选;考察了系统的热稳定性能,用电标定的方法对仪器在500、550、600、650、700、750、800 ℃时的量热系数进行了标定,绘制了正庚烷在800 ℃、载气流速为0.04 m3/h条件下热裂解的热谱曲线,以正庚烷为模型化合物测定了其热沉.实验证明仪器基线稳定,数据可靠,复现性能良好,有较高的灵敏度和测量精度,能够满足实验需要和工作要求. 相似文献
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荧光猝灭法和动态光散射法研究1-丙醇和2-丙醇对水溶液中 蛋白质构象的影响 总被引:1,自引:0,他引:1
应用荧光猝灭法和动态光散射技术测定牛血清白蛋白(BSA)与荧光素在正丙醇-水和异丙醇-水混合溶剂中的相互作用距离和BSA的流体动力学半径, 研究正丙醇和异丙醇对水溶液中蛋白质构象的影响. 结果显示, 正丙醇-水和异丙醇-水混合溶剂中BSA与荧光素的相互作用距离和BSA的流体动力学半径随着正丙醇和异丙醇浓度的增加而先减小后增大, 表明低浓度的正丙醇和异丙醇有利于蛋白质形成紧密的构象, 而较高浓度的正丙醇和异丙醇则破坏蛋白质的紧密构象. 试验中观察到BSA与荧光素在正丙醇-水混合溶剂中的结合距离大于同浓度的异丙醇-水混合溶剂中的结合距离, 而BSA在前者的流体动力学半径小于后者, 说明无支链的正丙醇分子易于与蛋白质的疏水基团产生较强的疏水相互作用, 而带支链的异丙醇分子的疏水性较弱, 有利于与蛋白质分子的亲水基团相互作用而积聚在蛋白质表面. 相似文献
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