title: Glucose oxidase stabilization against thermal inactivation using high hydrostatic pressure and hydrophobic modification.
abstract: High hydrostatic pressure (HHP) stabilized glucose oxidase (GOx) against thermal inactivation. The apparent first-order kinetics of inactivation of GOx were investigated at 0.1-300 MPa and 58.8-80.0°C. At 240 MPa and 74.5°C, GOx inactivated at a rate 50 times slower than at atmospheric pressure at the same temperature. The apparent activation energy of inactivation at 300 MPa was 281.0 ± 17.4 kJ mol-1or 1.3-fold smaller than for the inactivation at atmospheric pressure (378.1 ± 25.6 kJ mol-1). The stabilizing effect of HHP was greatest at 74.5°C, where the activation volume of 57.0 ± 12.0 cm3mol-1was highest compared to all other studied temperatures. Positive apparent activation volumes for all the treatment temperatures confirmed that HHP favors GOx stabilization. A second approach to increase GOx stability involved crosslinking with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and either aniline or benzoate. The modified enzyme remained fully active with only slight increases in KM(1.3-1.9-fold increases for aniline and benzoate modification, respectively). The thermal stability of GOx increased by 8°C with aniline modification, while it decreased by 0.9°C upon modification with benzoate. Biotechnol. Bioeng. 2017;114: 516-525. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Department of Food Science and Technology, University of Georgia, Food Science Building, 100 Cedar St., Athens, Georgia 30602.
authors.forename: Ali
authors.initials: A
authors.lastname: Halalipour
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Duff
authors.affiliation: Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Howell
authors.affiliation: Department of Food Science and Technology, University of Georgia, Food Science Building, 100 Cedar St., Athens, Georgia 30602.
authors.forename: José I
authors.initials: JI
authors.lastname: Reyes-De-Corcuera
mesh_terms: D000814:Aniline Compounds; D001234:Aspergillus niger / Q000201:enzymology; D001565:Benzoates; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D006874:Hydrostatic Pressure; D007700:Kinetics
chemical_list: D000814:Aniline Compounds; D001565:Benzoates; D005656:Fungal Proteins; D005949:Glucose Oxidase; C023650:aniline
keywords: enzyme stabilization; glucose oxidase; high hydrostatic pressure; hydrophobic modification; inactivation kinetics