Studies on the interaction of heparin with lysozyme by multi-spectroscopic techniques and atomic force microscopy

• A resonance Rayleigh scattering method was established for determination of heparin.
• Interaction between heparin with lysozyme was investigated by spectroscopic techniques.
• The conformational and topography change of lysozyme was explored before and after complexing with heparin.

The interaction between heparin (Hep) and lysozyme (Lyso) in vitro was studied by fluorescence, UV–vis, circular dichroism (CD), resonance Rayleigh scattering (RRS) spectroscopy and atomic force microscopy (AFM) under normal physiological conditions. UV–vis spectra of Lyso showed the absorbance was significantly increased with the addition of Hep. Fluorescence studies revealed that the emission quenching of Lyso with Hep was initiated by static quenching mechanism. CD spectral studies showed that Hep induced conformational changes in the secondary structure of Lyso. RRS spectra of Lyso showed the intensity of scattering was significantly increased with the addition of Hep and the enhanced RRS intensities were proportional to the concentration of Hep in a certain range. Thus, a new RRS method using Lyso as a probe could be used for the determination of Hep. The detection limit for Hep was 3.9 ng mL− 1. In addition, the shape of the complex was characterized by AFM. The possible reaction mechanism and the reasons for the enhancement of RRS intensity had been discussed through experimental results.

The interaction between heparin and lysozyme was studied by fluorescence, UV–vis, circular dichroism, resonance Rayleigh scattering spectroscopy and atomic force microscopy.Figure optionsDownload as PowerPoint slide