Stabilization of horseradish peroxidase in silk materials

Abstract

Horseradish peroxidase (HRP) is widely used as an indicator enzyme in enzyme immunoassays, enzyme electrodes, effluent treatment and synthetic organics. Previous studies showed that HRP was not stable in solution especially for low concentration solutions. It is important to prevent HRP from losing its activity. In the present study, we describe HRP stabilization in silk fibroin solution and in silk films. The results showed that HRP activity increased 30%―40% after being added into silk solution. The half-life time of HRP activity was 25 days at room temperature and 1h at 60°C in silk solution while it was only 2.5h at room temperature and 0.3h at 60°C in PBS buffer. The HRP activity in silk film still remained at 24%, 22%, 17%, when compared with the original amount of activity, after being immobilized in silk films stored at 4°C, room temperature and 37°C for 5 months, respectively. Electrostatic interactions and hydrophobic interactions between silk and HRP might account for this improved stabilization. Silk fibroin can be used as an HRP protecting reagent in solution and in films.

Keywords

stabilization / horseradish peroxidase (HRP) / enzyme / silk fibroin