Stabilization of bovine lactoperoxidase in the presence of ectoine

Lactoperoxidase (LPO) is a heme peroxidase with various applications in industry and medicine. In this study, the effects of ectoine, as a compatible solute, on the structure, thermal stability, thermodynamic parameters, activity, and stability of LPO have been investigated. The results showed that the catalytic activity of LPO was improved by increasing ectoine concentration. The UV-visible absorption spectroscopy and FTIR spectra studies indicated that ectoine could bind to the LPO spontaneously. Moreover, ectoine increased the enzyme Tm and Gibbs free energy. The fluorescence measurements showed that LPO fluorescence was quenched in the presence of ectoine. The quenching mechanism was probably a static quenching by forming a ground state complex. The thermodynamic parameters indicated that hydrogen bonding and Vander Waals forces played a key role in the LPO-ectoine interaction process. The findings suggest that ectoine could be used as a lactoperoxidase stabilizing agent for industrial or medical purposes.