Abstract

The densities of solutions of L-tryptophan (Trp) in water and sodium dodecyl sulfate (SDS) in Trp aqueous solutions are measured in a wide range of temperatures (293.15, 298.15, 303.15, 308.15, and 313.15) K using a DMA 5000 М density meter (Anton Paar).The apparent molar volumes (\({{V}_{{\varphi ,{\text{SDS}}}}}\)) of sodium dodecyl sulfate in the 0.0010–0.0199 mol kg⁻¹ range of concentrations and its limiting apparent molar volumes at infinite dilution (\(V_{{\varphi ,{\text{SDS}}}}^{^\circ }\)) in solutions containing the amino acid (at a fixed concentration of 0.01 mol kg^–1) are determined. A rise in the first critical micelle concentration from m = 0.0080 for SDS solutions in water to m = 0.0099 for SDS solutions with Trp is observed. Values of derivatives (\(\partial V_{{\varphi ,{\text{SDS}}}}^{^\circ }\)/∂T)_p and (\({{\partial }^{2}}V_{{\varphi ,{\text{SDS}}}}^{^\circ }\)/∂T ²)_p, and the partial molar volumes of SDS transfer from water to amino acid aqueous solutions, are calculated. Results are discussed by considering different types of intermolecular interaction in the given solutions. Quantum-chemical DFT/B97D modeling of the complexes between SDS and L-tryptophan zwitterion is done using a combination of basis set 6-311++G(2d,2p) and Grimme’s functional hybrid exchange correlation with a dispersion correction. The polarizable continuum model (PCM) is used to determine the structure and energies of formation of the SDS…Trp complexes with allowance for hydration effects.

中文翻译：

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通过密度测定法和计算机建模研究十二烷基硫酸钠和 L-色氨酸之间的相互作用

摘要

L-色氨酸 (Trp) 的水溶液和十二烷基硫酸钠 (SDS) 的 Trp 水溶液的密度在很宽的温度范围（293.15、298.15、303.15、308.15 和 313.15）K 下使用 DMA 5000 进行测量密度计 (Anton Paar)。十二烷基硫酸钠在 0.0010–0.0199 mol kg ^{-1 中的}表观摩尔体积 ( \({{V}_{{\varphi ,{\text{SDS}}}}}\)在含有氨基酸（固定浓度）的溶液中无限稀释（\(V_{{\varphi ,{\text{SDS}}}}^{^\circ }\)）的浓度范围及其限制表观摩尔体积0.01 mol kg ^–1 ) 被确定。第一临界胶束浓度从 SDS 水溶液的m = 0.0080上升到m 观察到含有 Trp 的 SDS 溶液 = 0.0099。导数的值 ( \(\partial V_{{\varphi ,{\text{SDS}}}}^{^\circ }\) /∂ T ) _p和 ( \({{\partial }^{2}}计算 V_{{\varphi ,{\text{SDS}}}}^{^\circ }\) /∂ T ² ) _p和 SDS 从水转移到氨基酸水溶液的偏摩尔体积。通过考虑给定溶液中不同类型的分子间相互作用来讨论结果。使用基组 6-311++G(2 d ,2 p) 和具有色散校正的 Grimme 功能混合交换相关性。极化连续介质模型 (PCM) 用于确定 SDS…Trp 复合物的结构和形成能量，并考虑水合效应。