利用荧光光度法研究了meso-四(4-羟基苯基)卟啉-锌金属卟啉(TPP-Zn)与牛血清白蛋白(BSA)之间的结合反应。TPP-Zn对于BSA有荧光猝灭作用,基于TPP-Zn对BSA内源荧光的猝灭机理,测定了两者之间在不同温度下的结合常数,温度在27,35和42℃时,利用荧光猝灭法测得的结合常数K分别为1.521×10₆ L·mol^-1,7.048×10₅ L·mol－1,1.473×105 L·mol^-1,各温度下的最大扩散碰撞猝灭速率常数Kq均大于2.0×1010 L·mol^-1·s^-1,由此判定猝灭类型为静态猝灭。根据Frster非辐射能量转移理论,确定了TPP-Zn与BSA之间的能量转移效率E,能量给体(BSA)与受体(TPP-Zn)之间的结合距离r=3.72<7 nm,符合非辐射能量转移条件。依据热力学参数ΔG<0,ΔH<0和ΔS>0确定了TPP-Zn与BSA之间的作用力主要是静电引力。

In the present paper,the binding reaction between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin (TPP-Zn) and bovine serum albumin (BSA) was studied at different temperatures by fluorescence method.It was shown that meso-tetra-(4-hydroxyphenyl)-Zn porphyrin has a strong ability of quenching the fluorescence of bovine serum albumin.Based on the mechanisms of fluorescence quenching of bovine serum albumin caused by meso-tetra-(4-hydroxyphenyl)-Zn porphyrin,the binding constants between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin and bovine serum albumin were measured under different temperatures.The experiment showed that meso-tetra-(4-hydroxyphenyl)-Zn porphyrin and bovine serum albumin have strong interactions.The binding constants of the reaction at 27 ℃,35 ℃ and 42 ℃ were 1.521×106 L·mol-1,7.048×105 L·mol-1 and 1.473×105 L·mol-1,respectively,and were decreased with increasing the temperature.The constants of maximum diffusion collision quenching rate-Kq were above 2.0×1010 L·mol-1·s^-1.Therefore,the sort of quenching between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin and bovine serum albumin was determined as static quenching.By the theory of Frster of non-radiation energy transfer,the binding distance and the energy transfer efficiency at 27 ℃ between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin (accepter of energy) and bovine serum albumin (donor of energy) were obtained, respectively.The binding distance was 3.72 nm,which is less than 7 nm,therefore,the interaction was similar to the non-radiation energy transfer,and the static quenching was further proved.According to the thermodynamic parameters, the main sorts of binding force between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin and bovine serum albumin could be judged as electrostatic force when ΔG＜0,ΔH＜0 and ΔS＞0.