硫唑嘌呤和巯嘌呤与牛血清白蛋白作用的荧光光谱研究

Study on the Binding Interaction of Azathioprine and 6-Mercaptopurine with Bovine Serum Albumin by Fluorescence Spectroscopy

采用荧光光谱法和紫外可见光谱法研究了硫唑嘌呤(AZP)和巯嘌呤(6-MP)与牛血清白蛋白(BSA)的结合反应特性。测定了不同温度下的结合常数KA及结合位点数n,研究证明AZP和6-MP对BSA内源荧光的猝灭机理均为静态猝灭,且主要以疏水作用力与BSA作用;利用同步荧光技术发现AZP和6-MP对BSA的构象均有影响;AZP和6-MP与BSA摩尔比为1∶1时,根据F rster偶极-偶极非辐射能量转移理论,计算出作用距离rAZP=2.94,r6-MP=4.10,说明AZP和6-MP与BSA的猝灭过程中都存在能量转移效应。

The binding characteristics of azathioprine （AZP） and 6-mercaptopurine （6-MP） with bovine serum albumin （BSA） were studied by fluorescence and absorption spectroscopy. The binding constant KA and binding sites were determined at different temperature. It was found that the fluorescence quenching mechanism of BSA was static quenching, due to AZP and 6-MP which were interacted with BSA mainly by hydrophobic force. It was showed by synchronal fluorescence technique that AZP and 6- MP had effect on the conformation of BSA. When they were combined with BSA by 1： 1, both UVabsorption and fluorescence spectrum of BSA were overlapped. According to F6rster non-radiation energy transfer theory, the interaction distances were less than 7 nm （rAZP ~ 2. 94, r6-Mp = 4. 10）, which showed there existed energy transfer effect during the quenching process of the interaction between AZP and 6-MP with albumin.