Abstract

Interaction between L-methionine (Met) and nicotinic acid (NA) in an aqueous buffer solution (pH 7.4) is studied via dissolution calorimetry and densimetry. The thermodynamic characteristics of the formation of a 1 : 1 molecular complex between Met and L at Т = 298.15 K are determined. The experimental density of the Met–L–buffer system is measured at T = 288.15, 298.15, 303.15, 308.15, and 313.15 K in the 0.0036 to 0.0367 mol/kg range of NA concentrations at a constant Met concentration (0.01249 mol/kg). It is shown that the extreme character of apparent molar volume–concentration dependences suggests the structure-strengthening effect NA has on solutions containing the amino acid (Met) with a slight shift of maxima with increasing temperature. The results are discussed in the context of the Gurney model.

中文翻译：

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L-蛋氨酸和烟酸在缓冲水溶液中的热力学性质

摘要

通过溶解量热法和比重法研究了缓冲液（pH 7.4）中L-蛋氨酸（Met）和烟酸（NA）之间的相互作用。一个1的形成的热力学特性：Met和L与在1分子复合物Т = 298.15 K的确定。Met–L–缓冲液系统的实验密度在T时测量在恒定的Met浓度（0.01249 mol / kg）下，NA浓度在0.0036至0.0367 mol / kg的范围内为288.15、298.15、303.15、308.15和313.15 K. 结果表明，表观摩尔体积-浓度依赖性的极端特征表明NA对含氨基酸（Met）的溶液具有结构强化作用，随着温度的升高，其最大值会有轻微变化。在Gurney模型的上下文中讨论了结果。