title: Enhanced thermal stability and pH behavior of glucose oxidase on electrostatic interaction with polyethylenimine.
abstract: Electrostatic interactions, mediated by ionic-exchange, between polyethylenimine (PEI) and glucose oxidase (GOx) were used to form GOx-PEI macro-complex, which were evaluated for pH and thermal stability of GOx. Under the experimental conditions, the complex had a dominant GOx presence on its surface and a hydrodynamic diameter of 205 ± 16 nm. Activity was evaluated from 40 to 75 °C, and at pH from 2 to 12. GOx activity in complex was maintained up to 70 °C and it was lost at 75 °C. In contrast, free GOx showed a maximum activity at 50 °C, which was completely lost at 70 °C. This difference, observed by fluorescence analysis, was associated with the compact unfolded structure of GOx in the complex. This GOx stability was not observed under pH variations, and complex formation was only possible at pH ≥ 5 where enzymatic activity was diminished by the presence of PEI.
authors: Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., Mexico.
authors: Silvia G
authors: SG
authors: Padilla-Martínez
authors: Facultad de Ciencias Químicas, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., Mexico.
authors: Lucía
authors: L
authors: Martínez-Jothar
authors: Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., Mexico.
authors: José G
authors: JG
authors: Sampedro
authors: Departamento de Ciencias Naturales - DCNI, Universidad Autónoma Metropolitana Unidad Cuajimalpa, Av. Vasco de Quiroga 4871, Cuajimalpa, Santa Fe, 05348 Mexico City, Mexico.
authors: Ferdinando
authors: F
authors: Tristan
authors: Instituto de Física, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, 78000 San Luis Potosí, S.L.P., Mexico. Electronic address: elias@ifisica.uaslp.mx.
authors: Elías
authors: E
authors: Pérez
mesh_terms: D001230:Aspergillus / Q000201:enzymology; D004795:Enzyme Stability; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005949:Glucose Oxidase / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D009391:Nephelometry and Turbidimetry; D011094:Polyethyleneimine / Q000378:metabolism*; D012996:Solutions; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D013696:Temperature
chemical_list: D012996:Solutions; D005182:Flavin-Adenine Dinucleotide; D011094:Polyethyleneimine; D005949:Glucose Oxidase
keywords: Enzymatic activity; Glucose oxidase; Polyelectrolyte complex