Immobilization of cycloisomaltooligosaccharide glucanotransferase for the production of cycloisomaltooligosaccharides from dextran

Immobilization of cycloisomaltooligosaccharide glucanotransferase (CITase) and its application in the production of cycloisomaltooligosaccharides (CIs ) from dextran were studied. Among Various carrier materials examined, the enzyme adsorbed physically on Chitopearl BCW-3505 showed the highest activi ty (1.75 U/ml carrier). The activity remaining was 35%. The maximum CI yiel d in batch reactions at 0.2, 2 and 10% dextran was 28, 24 and 12%, respecti vely. The maximum CI yield at 2% dextran (24%) was slightly less than that with the free enzyme under the same conditions (26%). The concentration of linear oligosaccharides, the byproducts in the reaction mixture, was greate r with the immobilized CITase than the free enzyme. The immobilized CITase was less thermostable than the free enzyme by about 10 degreesC. The patter n of influence of Ca2+ concentration on the thermostability differed betwee n the free and immobilized CITase. A Ca2+ concentration of 50-100 mM was op timum for the thermostability of the immobilized CITase, 10-50 mM for the f ree enzyme. CIs were produced continuously by a column system packed with t he immobilized enzyme at 40 degreesC with a space Velocity (SV) of 6 h(-1). The three quarters life time was 4 weeks. We think that relatively long li fe time at fast SV was accomplished and CI production cost by this method s hould be lower than the batch reaction. This is the first report on immobil ization of CITase. (C) 2001 Elsevier Science Inc. All rights reserved.