Novel encapsulation of horseradish peroxidase and its activity

Horseradish peroxidase (HRP) was chemically modified to get unsaturated double bonds at the surface by N-acryloxysuccinimide. The free radical polymerization was initiated in a copolymer system, which contained acrylamide and one of four kinds of monomers, PEG400-diacrylate ester (A), PEG400-dimethacrylate ester (B), PEG200-diacrylate ester (C) and PEG200-dimethacrylate ester (D). Four novel encapsulated HRP were obtained and there were multipoint connected network and thin shell structure at the surface of enzymes. Results show that the activity of encapsulated enzymes with PEG200(400)-diacrylate ester remains high and the stability is enhanced. C-HRP retains 47.9%, 39.7%, 76.5% of its relative activity under conditions of pH 3.0, 11.0 and 70°C, respectively. When C-HRP was reused by five times, C-HRP was retained 62.1% of its initial activities. When encapsulated HRP was soaked for 30 days in SDS and urea solution, the relative activities of four encapsulated HRP were 36% of their initial activities, which showed that the novel encapsulated method can retain higher activity and stability.