title: Purification and characterization of a novel lichenase from Bacillus licheniformis GZ-2.
abstract: A novel lichenase from Bacillus licheniformis GZ-2 was purified to homogeneity by two steps ion-exchange chromatography with a specific activity of 8231.3 U/mg. The purified enzyme showed as a single protein band with a molecular mass of 25 kDa. The optimum pH and temperature for the enzyme activity were 6.5 and 60 °C, respectively. The enzyme exhibited strict specificity for β-1,3-1,4-d-glucans. The kinetic parameters Km and Vmax were 5.11 mg/mL and 2097 µmol/Min/mg for lichenan and 7.42 mg/mL and 1440 µmol/Min/mg for barley β-glucan. Compared to most of the reported β-1,3-1,4-glucanases (lichenase), the activity of the purified enzyme for lichenan was much higher than that for barley β-glucan. The main products of β-glucan hydrolyzed by the lichenase were cellubiosyltriose (DP3) and cellutriosyltraose (DP4). The lichenase gene from B. licheniformis GZ-2 was cloned and sequenced. The open reading frame of gene gz-2 contained 642 bp coding for a 214 amino acid mature protein. The gene was cloned into an expression vector pET 28a and expressed in Escherichia coli BL21. The activity in cell lysate supernatant was 137.9 U/mg.
authors.affiliation: College of Biotechnology and Pharmaceutical Engineering, Nanjing University of Technology, Nanjing, People's Republic of China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gao
mesh_terms: D000069976:Bacillus licheniformis / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D004789:Enzyme Activation; D004926:Escherichia coli / Q000166:cytology / Q000378:metabolism; D006026:Glycoside Hydrolases / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013696:Temperature
chemical_list: D006026:Glycoside Hydrolases; C028020:licheninase
keywords: Bacillus licheniformis; characterization; lichenase