Preparation and characterization of gelatin hydrogel support for immobilization of Candida Rugosa lipase

Abstract

A series of gelatin hydrogels were prepared by crosslinking method using glutaraldehyde (GA). The hydrogels were characterized by gel formation, swelling/degradation tests, and FTIR analysis. The variations of swelling percentages (S%) with time, temperature, and pH were determined. It is found that the increasing amount of GA causes the decreasing in S% values from 366 to 213% and G-1 was found to be the most swollen hydrogel at pH 7.4 and 37°C. Degradation tests of hydrogel samples were carried out and G-1 hydrogel, which contained the least amount of GA, degraded more rapidly than the others. G-2 hydrogel was chosen for immobilization studies and this procedure was carried out by activation of the hydrogel disc with N-(3-dimethylaminopropyl)-N-ethylcarbodiimid (CDI) coupling agent. The kinetic parameters, K_m and V_max, were calculated. K_m values of free and immobilized lipases were found to be 0.290, 0.422 mM while V_max values were calculated as 0.089, 0.080 mM.min⁻¹, respectively. For the free and immobilized system, the enzymes retained 32% and 92% of their initial activities, respectively, at the end of 48 days of storage. After using the mentioned immobilized system repeatedly 10 times, it retained 68% of its original activities.

Keywords::

• Hydrogels
• gelatin
• swelling
• degradation
• lipase immobilization