ABSTRACT
The mutation had dramatic effect on the kinetic and thermodynamic parameters inferring thermostability of endo-glucanase from Cellulomonas biazotea mutant 51 SM(r). The denaturation activation energies of native and mutated enzymes were 73.3 and 68.8 kJ/mol respectively. They showed compensation effect at 55 degrees C. Both enthalpy and entropy values of irreversible thermal inactivation for mutated enzyme were decreased suggesting that the mutation partly stabilized the enzyme.
Subject(s)
Cellulomonas/enzymology , Glucosidases/chemistry , Cells, Cultured , Cellulase/chemistry , Cellulase/metabolism , Cellulomonas/chemistry , Endopeptidases , Enzyme Stability , Extracellular Space/chemistry , Extracellular Space/enzymology , Glucosidases/genetics , Glucosidases/metabolism , Hot Temperature , Kinetics , Mutation , Protein Conformation , Thermodynamics , Urea , beta-Glucosidase/chemistry , beta-Glucosidase/metabolismABSTRACT
The maximum product yield of endo-glucanase (650 IU g(-1) substrate) from Cellulomonas biazotea mutant 51 Sm(r) was 1.5- to 2.5-fold more than was produced by the wild type cells and was twice that reported by previous researchers. Mutation substantially improved the enthalpy (DeltaH (*)) and entropy of activation (DeltaS (*)) for product formation, turnover number, specificity constant activation energy, free energies for transition state formation and substrate binding for CMC hydrolysis respectively.