RESUMO
The time course of dextransucrase production by immobilized cells of Leuconostoc mesenteroides DSMZ 20241 in calcium alginate beads, the concentration of alginate gel, the size of bead inoculum and the successive reuse of beads were studied. Isolation and partial purification of the crude dextransucrase were carried out by fractional precipitation with acetone or ammonium sulfate separately. The fraction obtained at 75% ammonium sulfate saturation was most active. Further purification was conducted by gel filtration on sephadex G-100 and the most active protein peak was rechromatographed on CM-sephadex C-50. Immobilization of the purified enzyme on various supports was carried out. The enzyme had a relatively low thermostability, but the immobilized enzyme was more resistant to different heat treatments than the free enzyme. Some ions as Zn+2 and lead partially inhibited the activities of different purified dextransucrase preparations, while other ions as Ca+2 and Fe+3 enhanced their activities