[Study on interaction mechanism between meso-tetra-(4-hydroxyphenyl)-Zn porphyrin and bovine serum albumin by fluorescence method].

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 ΔG0,ΔH0 and ΔS0.