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Preparation and characterization of tyrosinase immobilized gelatin films
In this work, tyrosinase enyzme was immobilized on gelatin films by using entrapment and adsorption. In entrapment method, glutaraldehyde was used to crosslink the gelatin matrix. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), contact angle were used for characterization of the films; UV spectrophotometer was used for measurement of the catalytic activity of the tyrosinase immobilized films in catechol oxidation reaction. The pH and temperature, enyzme and substrate concentration effects on the activity of enzyme were investigated. Immobilization of enyzme to gelatin support increases the pH, temperature and operational stability due to the appropriate flexibility and structural rigidity. Activity of immobilized enyzme has decreased compared to free enyzme activity due to the steric hinderance effect and mass transfer limitations. The reusability of the enzyme entrapped gelatin film was also investigated; there was almost 60% decrease in activity of the film after fifth usage. During activity measurement, the color of the gelatin films becomes brown showing that quinone produced with enyzmatic reaction was bound on the film.