Abstract: Sodium alginate and chitosan were used as the carriers for immobilizing linoleate isomerase by entrapment and cross-linking entrapment methods. The immobilization conditions of linoleate isomerase and properties of immobilized linoleate isomerase were investigated. The results indicated that the optimal conditions for immobilizing linoleate isomerase were 3 g/100 mL sodium alginate, 2 g/100 mL CaCl2 and 0.3 g/100 mL glutaraldehyde. The optimal temperature and pH for the conversion of linoleic acid (LA) to conjugated linoleic acid (CLA) were 50 ℃ and 5.0, respectively. The thermal and pH stabilities of immobilized linoleate iosmerase were better than those of native enzyme in the range of 20－60 ℃ and pH 2－8. The Km of immobilized linoleate iosmerase was 0.36 mg/mL. After sixth repeated use, the immobilized enzyme remained 70.6% of its original activity. It could increase CLA production by 50% when compared with native linoleate isomerase.

Key words: linoleate isomerase, sodium alginate, immobilization, conjugated linoleic acid (CLA)