title: Kinetic and thermodynamic characterization of a halotolerant β-galactosidase produced by halotolerant Aspergillus tubingensis GR1.
abstract: β-Galactosidase from halotolerant Aspergillus tubingensis GR1 was purified by two-step purification process comprising ammonium sulfate precipitation followed by size exclusion chromatography (SEC). The recovery of β-galactosidase after SEC was found to be 1.40% with 58.55-fold increase in specific activity. The molecular weight of β-galactosidase protein was found to be 93 kDa by SDS-PAGE. Activation energy for O-nitrophenol β-D-galactopyranoside (ONPG) hydrolysis was 32.88 kJ mol(-1), while temperature quotient (Q(10)) was found to be 1.375. The enzyme was found to be stable over wide pH range and thermally stable at 60-65°C up to 60 min of incubation while exhibited maximum activity at 65°C with pH 3.0. V(max), K(m), and K(cat) for ONPG were found to be 2000 U ml(-1), 8.33 mM (ONPG), and 101454 s(-1), respectively. Activation energy for irreversible inactivation Ea(d) of β-galactosidase was 100.017 kJ mol(-1). Thermodynamic parameters of irreversible inactivation of β-galactosidase and ONPG hydrolysis were also determined. However, β-galactosidase enzyme activity was activated significantly in the presence of 15% NaCl and hence shows activity up to 30% NaCl concentration.
authors: Department of Microbiology, Shri A.N. Patel P.G. Institute, Sardar Patel University, Anand, Gujarat, India.
authors: Gopalkumar G
authors: GG
authors: Raol
authors: Department of Microbiology, Shri P. H. G. Muni. Arts and Science College, Gujarat University, Kalol, Gujarat, India.
authors: B V
authors: BV
authors: Raol
authors: B.R.D. School of Biosciences, Sardar Patel University, Vallabh Vidyangar, Gujarat, India.
authors: Vimal S
authors: VS
authors: Prajapati
authors: B.R.D. School of Biosciences, Sardar Patel University, Vallabh Vidyangar, Gujarat, India.
authors: Kamlesh C
authors: KC
authors: Patel
mesh_terms: D001230:Aspergillus / Q000201:enzymology* / Q000378:metabolism; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007700:Kinetics; D008970:Molecular Weight; D009598:Nitrophenylgalactosides / Q000378:metabolism; D055049:Salt Tolerance; D012965:Sodium Chloride / Q000494:pharmacology*; D013696:Temperature; D013816:Thermodynamics; D001616:beta-Galactosidase / Q000302:isolation & purification* / Q000378:metabolism*
chemical_list: C055012:2-nitrophenylgalactoside; D009598:Nitrophenylgalactosides; D012965:Sodium Chloride; D001616:beta-Galactosidase
keywords: Aspergillus tubingensis; Halotolerant; Kinetics; Thermodynamics; β-Galactosidase