伊文思蓝作荧光探针研究牛血清白蛋白与氨苄青霉素之间的竞争反应

Studies on Competitive Reaction Between Bovine Serum Albumin and Ampicillin with Evans Blue as Fluorescent Probe by Fluorescence Spectroscopy

用伊文思蓝(Evans blue,EB)作荧光探针研究了氨苄青霉素(Ampicillin,A)对牛血清白蛋白(Bovine serum albumin,BSA)的竞争反应.伊文思蓝与牛血清白蛋白作用,使牛血清白蛋白荧光发生猝灭,根据Stern-Volmer方程及荧光寿命研究了荧光猝灭的类型及机理.结果表明,猝灭类型为静态猝灭,即伊文思蓝和牛血清白蛋白形成了一种稳定的复合物.伊文思蓝与牛血清白蛋白的结合常数KBSA-EB=1.122×106L/mol,结合点数n=0.9935,并确定了EB和BSA之间的热力学常数及作用力类型.当加入氨苄青霉素后,牛血清白蛋白的相对荧光强度恢复.这表明氨苄青霉素与伊文思蓝对牛血清白蛋白发生了竞争反应.探讨了该竞争反应的相关机理,求出了伊文思蓝与氨苄青霉素的结合常数为K=7.131×105L/mol.

The competitive reaction between ampicillin and bovine serum albumin （BSA） was studied with Evans blue（EB） as a fluorescence probe by the fluorescence spectroscopy. Fluorescence quenching occurred between the bovine serum albumin and Evans blue. The static fluorescence quenching process was confirmed on the basis of the Stern-Volmer plot. The binding constant（KBSA-EB = 1. 122 × 10^6 L/mol） and the number of binding sites （ n = 0. 9935 ） were obtained. The enthalpy change, entropy change and free energy change were calculated, and the types of interaction force between EB and BSA were investigated. The relative fluorescence intensity of BSA was recovered gradually with increasing the concentration of ampicillin. The results indicate that there was a competitive interaction between ampicillin and EB for BSA, and the interaction mechanism was studied, the binding constant of EB with ampicillin, KEB-A =7. 131 × 10^5 L/mol, was obtained.