Dissection of the binding of hydrogen peroxide to trypsin using spectroscopic methods and molecular modeling

• The fluorescence of trypsin was quenched by hydrogen peroxide in a static quenching.
• Van der Waals forces and hydrogen bonding interactions are main forces during their binding process.
• No distinct activity change of trypsin occurs with the concentration of hydrogen peroxide less than 0.12 M.
• The toxicity of hydrogen peroxide to trypsin was reported at the molecular level.

Studies on the effects of environmental pollutants to protein in vitro has become a global attention. Hydrogen peroxide (H2O2) is used as an effective food preservative and bleacher in industrial production. The toxicity of H2O2 to trypsin was investigated by multiple spectroscopic techniques and the molecular docking method at the molecular level. The intrinsic fluorescence of trypsin was proved to be quenched in a static process based on the results of fluorescence lifetime experiment. Hydrogen bonds interaction and van der Waals forces were the main force to generate the trypsin-H2O2 complex on account of the negative ΔH0 and ΔS0. The binding of H2O2 changed the conformational structures and internal microenvironment of trypsin illustrated by UV–vis absorption, fluorescence, synchronous fluorescence, three-dimensional (3D) fluorescence and circular dichroism (CD) results. However, the binding site was far away from the active site of trypsin and the trypsin activity was only slightly affected by H2O2, which was further explained by molecular docking investigations.

Van der Waals forces and hydrogen bonds play the major role in the interaction of trypsin and hydrogen peroxide. The two hydrogen bonds are 1.901 Å and 1.682 Å formed between hydrogen peroxide and the GLN 210.A residue.Figure optionsDownload as PowerPoint slide