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

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.