【摘要】 目的研究咖啡因(CAF)与人血清白蛋白(HSA)间非共价结合特征,探讨CAF在血液中的存在方式。方法在模拟人体生理条件下,应用分子光谱技术,确定CAF与HSA相互作用方式、主要作用力类型及热力学参数。结果 CAF通过动态猝灭机制导致HSA荧光猝灭。当作用温度为298K和310K时,CAF与HSA表观结合常数(Kb)分别为3.35×105和9.53×104L·mol-1,结合位点数分别为1.23和1.09;二者结合距离为4.76 nm;主要作用力为氢键或范德华力;同步荧光图谱表明色氨酸、苯丙氨酸残基所处微环境极性增强。结论 CAF与HSA相互作用并形成超分子化合物,该结合作用是一自发过程。更多还原

【Abstract】 ObjectiveTo study the characteristic of noncovalent binding between caffeine(CAF) and human serum albumin(HSA),and discuss the way of existence in the blood of the caffeine. MethodsThe interaction mode and predominant intermolecular forces of CAF binding to HSA,and thermodynamic constant were studied in simulating physiological condition(pH7.40) by ultraviolet absorption and fluorescence spectra. ResultsCAF quenched the endogenous fluorescence of HSA via a dynamic quenching procedure.Apparent binding constants(Kb) were 3.35×105 L·mol-1(298K) and 9.53×104 L·mol-1(310K),and the number of binding-sites were 1.23(298K) and 1.09(310K),which decreased with a rise in temperature.The distance between the HSA and CAF was 4.76 nm,and predominant intermolecular forces between them were hydrogen bonding or Van Der Waals force interactions.The polarity around the Trp and Phe residues was increased and the hydrophobicity was decreased by synchronous fluorescence techniques. ConclusionCAF and HSA interact each other and form supermolecular compounds.The negative value of thermodynamic free energy change was taken as the evidence for the spontaneity of the binding of CAF to HSA.更多还原