Dynamic and structural properties of glucose oxidase enzyme

Haouz, Ahmed; Twist, Charles; Zentz, Christian; Tauc, Patrick; Alpert, Bernard

doi:10.1007/s002490050106

Cited by 74 publications

(50 citation statements)

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“…The FTIR spectrum of GOx powder displayed the two adsorption peaks characteristic of enzyme molecules at 1,654 and 1,540 cm -1 , due to C=O stretching vibrations of peptide bonds, and a combination of N-H in-plane bending and C-N stretching vibrations of the peptide groups, respectively [32]. The spectrum of the reference N-f is in good agreement with previous literature reports [33], showing vibrational bands associated with C-F, SO 3 H, and OH groups in the 1,000-500, 1,350-1,000, and 4,000-1,500 cm -1 regions, respectively.…”

Section: Enzyme Fuel Cell (Efc) Assembly and Efc Testsmentioning

confidence: 99%

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

et al. 2012

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We fabricated an enzyme fuel cell (EFC) device based on glucose as fuel and glucose oxidase (GOx) as biocatalyst. As a strategy to improve GOx stability, preserving at the same time the enzyme catalytic activity, we propose an immobilization procedure to entrap GOx in a polymer matrix based on Nafion and multiwalled carbon nanotubes. Circular dichroism (CD) spectra were recorded to study changes in the 3D structure of GOx that might be generated by the immobilization procedure. The comparison between the CD features of GOx immobilized and free in solution indicates that the shape of the spectra and position of peaks do not significantly change. The bioelectrocatalytic activity toward glucose oxidation of immobilized GOx was studied by cyclic voltammetry and chronoamperometry experiments. Such electrochemical experiments allow monitoring the rate of GOx-catalyzed glucose oxidation and extrapolating GOx kinetic parameters. Results demonstrate that immobilized GOx has high catalytic efficiency, due the maintaining of regular and well-ordered structure of the immobilized enzyme, as indicated by spectroscopic findings. Once investigated the electrode structure-property relationship, an EFC device was assembled using the GOx-based bioanode, and sulfonated poly ether ether ketone as electrolyte membrane.Polarization and power density curves of the complete EFC device were acquired, demonstrating the suitability of the immobilization strategy and materials to be used in EFCs.

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Section: Enzyme Fuel Cell (Efc) Assembly and Efc Testsmentioning

confidence: 99%

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

et al. 2012

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“…In the presence of oxygen, the b-d-glucose (Glu) was reacted with GOD and oxidized to gluconolactone (GluAc) and hydrogen peroxide (H 2 O 2 ), and the reactions are expressed by Equations 1 and 2. Two protons and two electrons, transferred from the platinum substrate to the flavin moiety of the enzyme, were proposed [27]. After the reaction of glucose and GOD, the reduced-state of the enzyme reacts with ferricinium ion to form the oxidized-state of the enzyme and ferrocene.…”

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Amperometric Glucose Biosensor Based on Entrapment of Glucose Oxidase in a Poly(3,4‐ethylenedioxythiophene) Film

2006

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In this study, conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), is used as a matrix for the entrapment of glucose oxidase (GOD) and served as the working electrode for sensing glucose. The monomer, EDOT, is electropolymerized onto the platinum electrode by the cyclic voltammetric (CV) technique, scanned between 0.2 and 1.2 V (vs. Ag/AgCl/saturated KCl) in a phosphate buffer solution (PBS) containing GOD, which is entrapped into the PEDOT film simultaneously. The biosensor senses the reoxidative current of the mediator, ferricinium ions, with a constant applied potential of 0.35 V in the sensing system containing a phosphate buffer solution, ferricinium ions, and glucose. The indirect electrochemical method can efficiently reduce the sensing potential of the glucose. The sensing results show that the linear range of the calibration curve for the glucose concentration lies between 0.1 and 10.0 mM, which is a suitable level in the human body. Besides, the limit of detection and sensing sensitivity on glucose for the biosensor are 0.13 mM and 12.42 mA cm À2 M À1 , respectively. The response time of the biosensor, which is defined as the reaction current reaching 95% of the steady-state current, is about 4 -10 s. In the aspects of interferences on ascorbic acid (AA) and uric acid (UA), the sensing currents increased about 9.7% and 39.1%, respectively, when compared to the sensing current of glucose. Moreover, the biosensor shows a good stability in which the sensing current of the electrode retains 80% of its original one over a period of 18 days.

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“…A significant effort has been made to increase the stability of GOX. It is known that both the thermal stability and the dynamic properties of the enzyme depend on its redox state (11,12). Protein glycosylation affects the conformational dynamics of the active site and thus the activity of the enzyme (13).…”

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confidence: 99%

Irreversible Thermal Denaturation of Glucose Oxidase from Aspergillus niger Is the Transition to the Denatured State with Residual Structure

Žoldák

Zubrik

Musatov

et al. 2004

Journal of Biological Chemistry

127

105

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Glucose oxidase (GOX; ␤-D-glucose:oxygen oxidoreductase) from Aspergillus niger is a dimeric flavoprotein with a molecular mass of 80 kDa/monomer. Thermal denaturation of glucose oxidase has been studied by absorbance, circular dichroism spectroscopy, viscosimetry, and differential scanning calorimetry. Thermal transition of this homodimeric enzyme is irreversible and, surprisingly, independent of GOX concentration (0.2-5.1 mg/ml). It has an apparent transition temperature of 55.8 ؎ 1.2°C and an activation energy of ϳ280 kJ/mol, calculated from the Lumry-Eyring model. The thermally denatured state of GOX after recooling has the following characteristics. (i) It retains ϳ70% of the native secondary structure ellipticity; (ii) it has a relatively low intrinsic viscosity, 7.5 ml/g; (iii) it binds ANS; (iv) it has a low Stern-Volmer constant of tryptophan quenching; and (v) it forms defined oligomeric (dimers, trimers, tetramers) structures. It is significantly different from chemically denatured (6.67 M GdmHCl) GOX. Both the thermal and the chemical denaturation of GOX cause dissociation of the flavin cofactor; however, only the chemical denaturation is accompanied by dissociation of the homodimeric GOX into monomers. The transition temperature is independent of the protein concentration, and the properties of the thermally denatured protein indicate that thermally denatured GOX is a compact structure, a form of molten globulelike apoenzyme. GOX is thus an exceptional example of a relatively unstable mesophilic dimeric enzyme with residual structure in its thermally denatured state.Glucose oxidase (GOX 1 ; ␤-D-glucose:oxygen oxidoreductase, EC 1.1.3.4) is a flavoenzyme that catalyzes oxidation of ␤-Dglucose by molecular oxygen to ␦-gluconolactone, which subsequently hydrolyzes spontaneously to gluconic acid and hydrogen peroxide. The enzyme contains one tightly, noncovalently bound FAD cofactor per monomer and is a homodimer with a molecular mass of 160 kDa, depending on the extent of glycosylation (1). Glucose oxidase from Aspergillus niger is glycosylated by neutral sugars (mostly mannose-like sugars) and by amino sugars (2). Several reports find that the sugar content may vary from 11 up to 30% (3-5).GOX is of considerable commercial importance. The enzyme has applications in the food and fermentation industry, in the textile industry, and as a molecular diagnostic and analytical tool in medical and environmental monitoring applications (6 -10).The study of GOX and its applications is limited by its conformational instability. A significant effort has been made to increase the stability of GOX. It is known that both the thermal stability and the dynamic properties of the enzyme depend on its redox state (11, 12). Protein glycosylation affects the conformational dynamics of the active site and thus the activity of the enzyme (13). However, the way in which glycosylation affects the stability of GOX is not known. On the other hand, modification of the glucose oxidase surface by artificial long polyethylene-glycol ...

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Dynamic and structural properties of glucose oxidase enzyme

Cited by 74 publications

References 0 publications

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

Development of glucose oxidase-based bioanodes for enzyme fuel cell applications

Amperometric Glucose Biosensor Based on Entrapment of Glucose Oxidase in a Poly(3,4‐ethylenedioxythiophene) Film

Irreversible Thermal Denaturation of Glucose Oxidase from Aspergillus niger Is the Transition to the Denatured State with Residual Structure

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