Kinetic and thermodynamic characteristic of Aspergillus awamori EM66 levansucrase

This study is a new trial aimed to solve levansucrase high cost and levan associated problems during the purification process. Also, kinetic and thermodynamic study was done to compare between the partial pure (PP) and purified forms (PF). Within this context, Aspergillus awamori EM66 levansucrase was produced constitutively (5.44 U.mL(-1)) using rice straw as the sole medium component. The enzyme was partially purified and was eluted as single protein after two purification steps. Its molecular weight was determined to be 44.5 KDa. The optimum temperature recorded 40 degrees C for both enzyme forms. While, the purification process lowering the enzyme pH from 5.2 to 4.0. The NaCl concentrations (0.5-3.0 M) pointed to the halophilic nature of the enzyme. The PP form retained about 76% of its original activity after 1 h at 55 degrees C while the other retained about 57% after 45 min. at the same temperature. The kinetic parameters K-m and V-max concluded that the PF was more efficient than the PP. The thermodynamic parameters such as E-a, E-d, T-1/2, D-value, also, Delta G*, Delta H* and Delta S* for activation recorded that the PP had higher stability than the PF. (C) 2018 Elsevier B.V. All rights reserved.