Catalytic and thermodynamic properties of immobilized Bacillus amyloliquefaciens cyclodextrin glucosyltransferase on different carriers

Bacillus amyloliquefaciens cyclodextrin glucosyltransferase (CGTase) was immobilized on 35 supports by different methods of immobilization. The immobilized enzymes were prepared by physical adsorption on chitin, ionic binding onto Amberalite IRA-45, covalent binding on Duolite D761, and entrapment in polyacrylamide had the highest recovered activity. The immobilized preparations retained 12.08-43.5% of the original specific activity exhibited by the free enzyme. Compared to the free enzyme, the immobilized preparations exhibited higher optimum temperature, lower activation energy, lower deactivation constant rate, higher half-life (T-1/2) values, and resistance to chemical denaturation. The values of thermodynamic parameters for irreversible inactivation indicated that immobilization significantly decreased entropy (Delta S*) and enthalpy of deactivation (Delta H*). The immobilized enzyme displayed higher K-m and lower V-max values. After using for 10 cycles, the retained catalytic activity were 30.0, 35.0, 69, and 54% of the initial values of the immobilized enzyme on chitin, Amberlite IRA-45, Duolite XAD761, and polyacrylamide respectively. (C) 2015 Elsevier B.V. All rights reserved.