Synthesis and characterisation of magnetic κ-carrageenan nanocomposites for chitinase33 enzyme immobilisation

Abstract

Chitinases are chitin-degrading enzymes that have wide biotechnological applications in the fields of medicine, agriculture and the industry. Production of chitinase on an industrial scale requires high protein expression. Pichia pastoris yeast is an important host for the rapid production and high levels of recombinant proteins. In this project, the fungal chit33 enzyme was expressed and purified in Pichia pastoris X-33, and the purified enzyme was immobilised to enhance the sustainability, activity, and reuse on the magnetite κ-carrageenan/chitosan nanocomposite as a biocatalyst. The synthesised nanoparticle was characterised using FTIR, SEM and EDS analysis. According to the results of enzyme activity measurement under different pH conditions, the temperature and time of the stabilised enzyme showed better activity and stability than the free enzyme. Compared to free enzyme and chitosan beads, in the magnetic κ-carrageenan/chit36 substrate the specific activity, pH tolerance, optimum temperature of the enzyme was improved. The enzyme stabilised in the magnetic cariogenic/chit33 substrate at 70°C maintains about 80% of its enzyme activity relative to the magnetic chitosan/chit36 bead and maintains about 40% of its activity after eight cycles of re-use of the enzyme.