Immobilization of Candida sp. Lipase on Nylon Net and Its Enzymatic Characteristics

Lipase(Candida sp.99-125) was immobilized on nylon net by glutaraldehyde as cross-linking agent.Effects of various parameters on the activity of immobilized lipase and characteristics of immobilized lipase were investigated.The maximum enzyme activity achieved at the following conditions: glutaraldehyde concentration of 3%,cross-linking time of 60 min,enzyme concentration of 10 mg/mL,and immobilized time of 6 h.The optimal temperature of immobilized lipase shifted from 45 ℃ to 50 ℃,compared with free lipase.The immobilized lipase maintained high activity in a broad pH range of 5.0 to 7.0,with optimum pH at 7.0,which was identical to that of the free lipase.Thermal,pH,and operational stabilities of lipase were greatly improved after immobilization onto nylon net.Immobilized lipase retained about 80% of the initial activity after fifth repeated use.The Km(0.57 mol/L) and Vmax(0.29 × 10-3mol/(L.s)) of immobilized lipase using olive oil as substrate was significantly higher as compared to free lipase.The immobilization of lipase decreased its affinity to substrate as compared to free lipase.