Abstract:

Recombinant dextransucrase was immobilized with sodium alginate and agar. The immobilization conditions and enzymological properties of the enzyme were also investigated. Results indicated that immobilized dextransucrase could retain high activity via the immobilization using 4% sodium polymannuronate mixed with 1% gelatin at the ratio of 1:1 mixing. The transformation efficiency of the immobilized dextransucrase still retained 40% after repeated transformation for 6 times. The optimal volume ratio between mixed carrier and enzyme solution was 2:1, which achieved the highest enzyme activity. The optimal reaction temperature, pH and sucrose concentration as the substrate for the immobilized recombinant dextransucrase were 40 ℃, 5.4 and 5 g/100mL, respectively. The enzyme activity remained 44% after storage at 35 ℃ for 1 h. The thermal stability of the immobilized enzyme was better than that of the free enzyme. The Km value of this immobilized dextransucrase was 28.35 mmol/L.

Key words: dextransucrase, immobilization, sodium alginate, enzymological property