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本文合成并表征了三种不同烷基链长度的季铵盐型阳离子表面活性剂:N-十二烷基-N-(2-羟乙基)-N,N-二甲基溴化铵(DHDAB)、N-十四烷基-N-(2-羟乙基)-N,N-二甲基溴化铵(THDAB)、N-十六烷基-N-(2-羟乙基)-N,N-二甲基溴化铵(CHDAB)。采用荧光光谱法、紫外-可见光谱法、动态光散射法和等温滴定量热法对三种表面活性剂与牛血清白蛋白(BSA)的相互作用进行研究。荧光光谱研究表明,三种表面活性剂主要与BSA分子内的色氨酸残基发生相互作用,导致蛋白质的构象发生变化,且表面活性剂烷基链越长,与BSA的相互作用就越强。BSA荧光猝灭的主要原因是静态猝灭,紫外光谱实验同样验证了静态猝灭的存在。等温滴定量热法结果表明低浓度的表面活性剂与BSA主要发生静电作用和疏水作用而放热。动态光散射结果表明高浓度的表面活性剂会使BSA结构被破坏。本文揭示了表面活性剂与BSA相互作用的机理,为表面活性剂的广泛应用提供了理论基础。
Three quaternary ammonium salt cationic surfactants of different alkyl chain lengths were synthesized and characterized in this paper: N-dodecyl-N- (2-hydroxyethyl) -N, N-dimethyl ammonium bromide DHDAB), N-tetradecyl-N- (2-hydroxyethyl) -N, N- dimethylammonium bromide (THDAB), N-hexadecyl-N- (2- hydroxyethyl) -N, N-dimethyl ammonium bromide (CHDAB). The interaction of three surfactants with bovine serum albumin (BSA) was studied by fluorescence spectroscopy, UV-Vis spectroscopy, dynamic light scattering and isothermal titration calorimetry. Fluorescence spectroscopy studies show that the three surfactants mainly interact with the tryptophan residues in the BSA molecule, resulting in the conformational changes of the protein. The longer the alkyl chain of the surfactant, the stronger the interaction with the BSA . The main reason for the fluorescence quenching of BSA is static quenching. The UV spectroscopy experiment also verifies the existence of static quenching. Isothermal titration calorimetry results show that the low concentration of surfactant and BSA mainly electrostatic interaction and hydrophobic and exothermic. Dynamic light scattering results show that the high concentration of surfactant BSA structure will be destroyed. This paper reveals the interaction between surfactant and BSA mechanism, which provides a theoretical basis for the widespread application of surfactants.