Thermal inactivation of immobilized enzymes: A kinetic study

Fischer, Jens Malte; Ulbrich, Renate; Ziemann, Romana; Flatau, S.; Wolna, Peter; Schleiff, M.; Pluschke, Volker; Schellenberger, Alfred

doi:10.1007/bf02995866

Cited by 25 publications

(4 citation statements)

References 17 publications

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“…In such cases and at a fixed potential, the enzyme deactivation kinetics is often of first order and can be described using an exponential decay equation. 30 The immobilized Bp BOD half-life at 25 °C estimated from a monoexponential fit was approximately 7 days, demonstrating that CF-CNT provides a friendly host-matrix for this enzyme immobilization.…”

Section: D Porous Materials For Biocatalyst Protection?mentioning

confidence: 90%

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell

Mazurenko

Monsalve

Infossi

et al. 2017

Energy Environ. Sci.

102

107

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International audienceUsing redox enzymes as biocatalysts in fuel cells is an attractive strategy for sustainable energy production. Once hydrogenase for H2 oxidation and bilirubin oxidase (BOD) for O2 reduction have been wired on electrodes, the enzymatic fuel cell (EFC) thus built is expected to provide sufficient energy to power small electronic devices, while overcoming the issues associated with scarcity, price and inhibition of platinum based catalysts. Despite recent improvements, these biodevices suffer from moderate power output and low stability. In this work, we demonstrate how substrate diffusion and enzyme distribution in the bioelectrodes control EFC performance. A new EFC was built by immobilizing two thermostableenzymes in hierarchical carbon felt modified by carbon nanotubes. This device displayed very high power and stability, producing 15.8 mW h of energy after 17 h of continuous operation. Despite the large available electrode porosity, mass transfer was shown to limit the performance. To determine the optimal geometry of the EFC, a numerical model was established, based on a finite element method (FEM). This model allowed an optimal electrode thickness of less than 100 mm to be determined, with a porosity of 60%. Thanks to very efficient enzyme wiring and high enzyme loading, non-catalytic signals for both enzymes were detected and quantified, enabling the electroactive enzyme distribution in the porouselectrode to be fully determined for the first time....

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Section: D Porous Materials For Biocatalyst Protection?mentioning

confidence: 90%

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell

Mazurenko

Monsalve

Infossi

et al. 2017

Energy Environ. Sci.

102

107

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“…The observed biphasic nature of the denaturation plots in milk may be due to a series-type inactivation mechanism (Gianfreda et al, 1984) or to the presence of isozymes of different stability which denature concurrently (Fischer et al, 1980). Both electrophoresis and isoelectric focusing indicated the presence of one major and one minor isozyme, with the latter exhibiting an average of 9.4 & 1.2% (n = 4) of the total activity.…”

Section: Resultsmentioning

confidence: 93%

Enhanced Thermostability of Lactase (Escherichia coli) in Milk

Mahoney

Wilder

1987

Journal of Food Science

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Denaturation of lactase in phosphate buffer was a first‐order process with a half‐life of 1.12 min at 60°C. Denaturation in milk was a biphasic first‐order process with a half‐life of 115 min at 60°C. Electrophoresis, isoelectric focusing and kinetic analysis all indicated the presence of two isozymes. The minor isozyme exhibited 9% of the total activity and was less thermostable in milk than the major isozyme. In the temperature range 53.5–60°C, the rate of denaturation of the major isozyme in milk was more than 100 times less than the rate in buffer. Arrhenius plots of denaturation in milk and buffer were biphasic. Above 56°C, Ea denaturation in milk and buffer was 187 Kcals/mole and 19.8 Kcals/mole, respectively; below 56°C Ea denaturation in milk and buffer was 36.8 Kcals/mole and 158 Kcals/mole, respectively.

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“…Other studies utilizing silicon dioxide as a support for immobilizing enzymes include kinetic studies on the thermal inactivation of various enzymes bound to silica as compared with other immobilizing supports 28 and stability of silica immobilized enzymes with respect to microbial growth." This latter group also studied various reactor designs such as the more conventional packed-column or stirred-tank reactors as well as a fluidized bed reactor.…”

Section: F Excipients and Immobilized Enzymesmentioning

confidence: 99%

Food applications and the toxicological and nutritional implications of amorphous silicon dioxide

Villota

Hawkes

Cochrane

1986

C R C Critical Reviews in Food Science and Nutrition

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The chemical and physical characteristics of the different types of amorphous silicon dioxide contribute to the versatility of these compounds in a variety of commercial applications. Traditionally, silicas have had a broad spectra of product usage including such areas as viscosity control agents in inks, paints, corrosion-resistant coatings, etc. and as excipients in pharmaceuticals and cosmetics. In the food industry, the most important application has been as an anticaking agent in powdered mixes, seasonings, and coffee whiteners. However, amorphous silica has multifunctional properties that would allow it to act as a viscosity control agent, emulsion stabilizer, suspension and dispersion agent, desiccant, etc. The utilization of silicas in these potential applications, however, has not been undertaken, partially because of the limited knowledge of their physiochemical interactions with other food components and partially due to their controversial status from a toxicological point of view. The main goal of this review is to compile current information on the incorporation of amorphous silicon dioxide as a highly functional and viable additive in the food processing industry as well as to discuss the most recent toxicological investigations of silica in an attempt to present some of the potential food applications and their concomitant toxicological implications. Some of the more significant differences between various silicas and their surface chemistries are presented to elucidate some of their mechanisms of interaction with food components and other biological systems and to aid in the prediction of their rheological or toxicological behavior.

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Thermal inactivation of immobilized enzymes: A kinetic study

Cited by 25 publications

References 17 publications

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell

Enhanced Thermostability of Lactase (Escherichia coli) in Milk

Food applications and the toxicological and nutritional implications of amorphous silicon dioxide

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Thermal inactivation of immobilized enzymes: A kinetic study

Cited by 25 publications

References 17 publications

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H2/O2enzymatic fuel cell

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H2/O2enzymatic fuel cell

Enhanced Thermostability of Lactase (Escherichia coli) in Milk

Food applications and the toxicological and nutritional implications of amorphous silicon dioxide

Contact Info

Product

Resources

About

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell

Impact of substrate diffusion and enzyme distribution in 3D-porous electrodes: a combined electrochemical and modelling study of a thermostable H₂/O₂enzymatic fuel cell