Amyloid Nano-biofibrils as a New Nano-Scaffold for Lipase Immobilization.

Abstract

Amyloids could be created under destabilizing conditions from various proteins. Having high chemical reactive groups makes the amyloid fibers suitable for enzyme stabilization. Imobilization of lipase as one of the stable classes of high catalytic power enzymes could be very valuable. In the present study, the lipase from Pseudomonas cepacia was immobilized on BSA amyloid nano-biofibrils and the kinetic parameters were compared with those of its free counterpart. The possibility of using this nano-material as a new nano-scaffold for lipase immobilization was investigated. Response surface methodology was used in this study to produce the maximum amounts of amyloid fibrils using Design Expert 7 software. Transmission electron microscopy was employed to confirm the presence of amyloid fibers. The stabilization process was performed by glutaraldehyde mediated covalent cross-links between the enzyme and amyloid fibers. Kinetic parameters including activity, specific activity, optimal pH and temperature and thermal stability of immobilized enzyme were compared with the free counterpart. The optimum conditions for fibrillogenesis were obtained at 4.36 mg.ml-1 of protein after 72 hours of mild agitation in a mixed citrate-phosphate buffer at the pH of 4.5 and the temperature of 80 ºC. The kinetic parameters of the immobilized lipase were improved in terms of activity, specific activity, Km and Vmax, optimal pH and temperature and thermal stability at 40 ºC. Amyloid fibrils with a diameter of less than 100 nm, as a new nano-scaffold, increased both the stability of lipase and other kinetic properties of the enzyme. Amyloid fibrils as a new chemically-rich nano-scaffold could be an appropriate matrix for lipase immobilization.