Modeling Enzymes Inhibition During Microparticles Formation

A mathematical model of enzymes inhibition during microparticles formation has been developed. The model is based on radial substrate diffusion through diffusion layer that surrounds microparticle. The inhibition of enzymes was explained by enzyme adsorption on surface of the microparticles and substrate diffusion limitation through the diffusion layer. The diffusion module is dependent on dimensions of the microparticle. The microparticles with diameter 2 µm may ensure 50% of an apparent activity decrease if half of peroxidase has been adsorbed. Further adsorption of peroxidase and aggregation of the microparticles increases the apparent inhibition

Modeling Enzymes Inhibition During Microparticles Formation

A mathematical model of enzymes inhibition during microparticles formation has been developed. The model is based on radial substrate diffusion through diffusion layer that surrounds microparticle. The inhibition of enzymes was explained by enzyme adsorption on surface of the microparticles and substrate diffusion limitation through the diffusion layer. The diffusion module is dependent on dimensions of the microparticle. The microparticles with diameter 2 µm may ensure 50% of an apparent activity decrease if half of peroxidase has been adsorbed. Further adsorption of peroxidase and aggregation of the microparticles increases the apparent inhibition

Biosensor Response at Mixed Enzyme Kinetics and External Diffusion Limitation in Case of Substrate Inhibition

The action of a biosensor containing non Michaelis-Menten enzyme was modeled at mixed enzyme kinetics and external diffusion limitation in the case of substrate inhibition. The calculations show that at the electrode surface multi steady-state concentrations of substrate may be generated if diffusion module is much larger than 1 and the substrate bulk concentration is much bigger than Michaelis-Menten parameter. The multi steady-state concentration generates multi response of the biosensor. The production of the multi steadystate may cause the biosensor response oscillation

Kinetics of Biocatalytical Synergistic Reactions

Kinetics of biocatalytical synergistic reactions has been analyzed at non-stationary state (NSS) and at quasi steady state (QSS) conditions. The application to the model kinetic constants taken from the first type of the experiments shows that QSS can be established for the enzyme and the mediator at time less than 1 s. Therefore, the analytical solution of the initial rate (IR) may be produced at relevant to an experiment time, and the dependence of the IR on substrates concentration may be analyzed rather easy. The use of kinetic constants from the second type of reactions shows that QSS is formed for the enzyme but not for the mediator. For this reason the modeling of the synergistic process was performed by solving the ordinary differential equations (ODE). For this purpose the novel program KinFitSim (c) was used

Modeling Trienzyme Biosensor at Internal Diffusion Limitation

A model of biosensor containing three immobilized enzymes utilizing consecutive substrate conversion in the chain was developed. The modeling was performed at an internal diffusion limitation and a steadystate condition. The calculations showed that significant response of biosensors was produced if diffusion modules were larger than 1 for all enzyme reactions. Due to diffusion limitation the apparent stability of biosensor response increased many times in comparison to stability of the most labile enzyme of the chain

The Effectiveness of Synergistic Enzymatic Reaction with Limited Mediator

Kinetics of biocatalytical synergistic reactions has been analyzed with special emphasis on stability and reactivity of mediators. The application to the model of kinetic constants taken from the experiments showed that the quasi steady state (QSS) for reduced and oxidized enzyme was achieved in 0.001 s. However, the QSS for the mediator was not established during measurable time. For this reason the kinetics of biocatalytical synergistic reactions was modeled by solving the ordinary differential equations using software package KinFitSim©. The calculations showed the increase of an apparent life-time of the mediator in the synergistic reaction. The apparent life-time was most affected by reactivity of mediator. The change of the mediator reactivity from 1 M−1s−1 to 105 M−1s−1 increased the apparent life-time from 19 s to 1538 s. This mediator reactivity can be achieved even for strongly endothermic reaction when difference of redox potential of substrate and mediator is 0.35 V. The increase of mediator life-time increased product yield

Macrokinetic Model of Catalase Electrode with Biphasic Enzyme Inhibition

Macrokinetics of catalase based enzyme electrode was investigated in presence of enzyme inhibitor – hydroxylamine. The modeling of the electrode was performed using biphasic scheme of enzyme inhibition and external diffusion limitation. The maximal enzyme electrode sensitivity was indicated at transition from diffusion to kinetically controlled mode. The fitting of experimental data demonstrated that the enzyme electrode had 70% of maximal sensitivit

Electronic Structure of Dodecyl Syringate Radical Suitable for ESR Molecular Quantum Computers

The neutral radical of dodecyl syringate is suggested as a candidate for molecular Electron Spin Resonance (ESR) quantum computers. The first principle of quantum chemical calculations indicates that this molecule with a stable delocalised electron spin may represent a qubit in quantum information processing. The spin density analysis exhibits that unpaired spin of the radical is delocalised in the region of not-compensated valence bond. Isotropic Fermi contact coupling constants and anisotropic spin dipole couplings was investigated and indicated the largest hyperfine splitting (HFS) of ESR spectra on atoms of the above mentioned region of not-compensated valence bond

Numerical Simulation of Electrochemical Processes at a Tubular Electrode. Application to Spectroscopy

A model of spectroelectrochemical cell design based on a tubular working electrode with optical fibers connected to a spectrometer entering it from two ends is built. Both current and absorbance responses of the cell are numerically simulated and the operation regimes are determined in terms of ranges of governing parameters for chronoamperometry and linear sweep voltammetry

Modelling of a microreactor on heterogeneous surface and an influence of microreactor geometry

A model of an action of the amperometric biosensors based on carbon paste electrodes encrusted with single microreactor is analyzed. The model is based on non stationary diffusion equations containing non-linear term related to the enzymatic reaction. The biosensors current, which is a function of the concentration gradient of the reaction product on the electrodes, is used for analyzing of dynamics of the reaction. An influence of a size of microreactor, a geometrical form of microreactor and a position of microreactor on the biosensors action is investigated