Study on the interaction between salicylic acid and catalase by spectroscopic methods

The interaction between catalase (CAT) and salicylic acid (SA) was studied by fluorescence and UV–vis spectroscopic techniques. The quenching mechanism of fluorescence of BSA by CAT was discussed to be a static quenching procedure. The number of binding sites n and apparent binding constant K was measured by fluorescence quenching method. The thermodynamics parameter ΔH, ΔG, ΔS were calculated. The results indicate the binding reaction was both entropy-driven and the enthalpy-driven, and the hydrogen bond and van der Waals force played major role in the binding reaction. The binding sites of SA with CAT was investigated to be approached the microenvironment of Trp by the synchronous fluorescence spectrometry. The distance r between donor (CAT) and acceptor (SA) was obtained according to Förster theory of non-radioactive energy transfer.