title: Effects of high pressure homogenization on the activity, stability, kinetics and three-dimensional conformation of a glucose oxidase produced by Aspergillus niger.
abstract: High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5-6.0 and a remarkable activity increase (30-300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO.
authors: Department of Food Technology (DTA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors: Alline Artigiani Lima
authors: AA
authors: Tribst
authors: Department of Food Science (DCA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Campinas, SP, Brazil; Brazilian Bioethanol Science and Technology Laboratory (CTBE/CNPEM), Campinas, SP, Brazil.
authors: Júnio
authors: J
authors: Cota
authors: Brazilian Biosciences National Laboratory (LNBio/CNPEM), Campinas, SP, Brazil.
authors: Mario Tyago
authors: MT
authors: Murakami
authors: Department of Food Technology (DTA), School of Food Engineering (FEA), University of Campinas (UNICAMP), Campinas, SP, Brazil.
authors: Marcelo
authors: M
authors: Cristianini
mesh_terms: D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000201:enzymology*; D002458:Cell Fractionation; D004795:Enzyme Stability; D005656:Fungal Proteins / Q000737:chemistry* / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D008969:Molecular Sequence Data; D011312:Pressure; D011487:Protein Conformation; D011489:Protein Denaturation
chemical_list: D005656:Fungal Proteins; D005949:Glucose Oxidase