Cellobiose dehydrogenase (CDH) isolated from Neurospora crassa was immobilized on Au electrodes, ... more Cellobiose dehydrogenase (CDH) isolated from Neurospora crassa was immobilized on Au electrodes, covered with self-assembled monolayers (SAMs) made of different thiolic compounds bearing -OH, -COOH or -NH2 as terminal functional groups. From cyclic voltammetric measurements, performed at different pH values, the catalytic efficiencies towards lactose oxidation were estimated for the immobilized CDH. The observed variations were explained in terms of: (i) the influence of the SAM structure on the direct electron transfer (DET) between CDH and the Au electrode surface; (ii) the variation of the catalytic activity of the enzyme, induced by changes of enzyme’s conformation. The dependence on pH, found for the standard formal potential of the heme group, confirms that, when CDH is deposited on thiolic SAMs, it is able to sustain an efficient DET process.
The flavocytochrome cellobiose dehydrogenase (CDH) is secreted by wood‐decomposing fungi, and is ... more The flavocytochrome cellobiose dehydrogenase (CDH) is secreted by wood‐decomposing fungi, and is the only known extracellular enzyme with the characteristics of an electron transfer protein. Its proposed function is reduction of lytic polysaccharide mono‐oxygenase for subsequent cellulose depolymerization. Electrons are transferred from FADH2 in the catalytic flavodehydrogenase domain of CDH to haem b in a mobile cytochrome domain, which acts as a mediator and transfers electrons towards the active site of lytic polysaccharide mono‐oxygenase to activate oxygen. This vital role of the cytochrome domain is little understood, e.g. why do CDHs exhibit different pH optima and rates for inter‐domain electron transfer (IET)? This study uses kinetic techniques and docking to assess the interaction of both domains and the resulting IET with regard to pH and ions. The results show that the reported elimination of IET at neutral or alkaline pH is caused by electrostatic repulsion, which preven...
In this article we describe production and characterisation of mutant pyranose dehydrogenase – an... more In this article we describe production and characterisation of mutant pyranose dehydrogenase – an excellent enzyme for fabrication of enzyme-based biosensors and bioanodes.
The search for an enzyme as a reagent for selective bioanalytical detection of the neurotoxic ami... more The search for an enzyme as a reagent for selective bioanalytical detection of the neurotoxic amino acid, β-N-oxalyl L-alpha, β-diaminopropionic acid, β-ODAP (found in grass pea, Lathyrus sativus) led to its redox catalytic reaction by glutamate oxidase (GluOx). Homogeneous kinetic studies and an immobilized GluOx reactor-based flow-injection assay were initially made for beta-ODAP with small immobilized GluOx/catalase glutamate destroying prereactors. The method was applied to examine the toxin content in processed grass pea. The kinetics and the equilibrium of the thermal isomerization of β-ODAP to the nontoxic isomer α-ODAP established that GluOx is specific to the neurotoxin. The first ever GluOx-based amperometric biosensor for liquid chromatography (LC) detection was reported in 1997. This biosensor coupled with a refractive index detector improved LC performance. The most recent work with GluOx resulted in MnO2-based screen-printed amperometric biosensor, with offline elimina...
The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganes... more The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganese peroxidase and laccase and possibly also cellobiose dehydrogenase, is reviewed and discussed in conjunction with their basic biochemical characteristics. It is shown that long‐range electron transfer between these enzymes and electrodes can be established and their ability to degrade lignin through a direct electron transfer mechanism is discussed.
Cellobiose dehydrogenase (CDH) isolated from Neurospora crassa was immobilized on Au electrodes, ... more Cellobiose dehydrogenase (CDH) isolated from Neurospora crassa was immobilized on Au electrodes, covered with self-assembled monolayers (SAMs) made of different thiolic compounds bearing -OH, -COOH or -NH2 as terminal functional groups. From cyclic voltammetric measurements, performed at different pH values, the catalytic efficiencies towards lactose oxidation were estimated for the immobilized CDH. The observed variations were explained in terms of: (i) the influence of the SAM structure on the direct electron transfer (DET) between CDH and the Au electrode surface; (ii) the variation of the catalytic activity of the enzyme, induced by changes of enzyme’s conformation. The dependence on pH, found for the standard formal potential of the heme group, confirms that, when CDH is deposited on thiolic SAMs, it is able to sustain an efficient DET process.
The flavocytochrome cellobiose dehydrogenase (CDH) is secreted by wood‐decomposing fungi, and is ... more The flavocytochrome cellobiose dehydrogenase (CDH) is secreted by wood‐decomposing fungi, and is the only known extracellular enzyme with the characteristics of an electron transfer protein. Its proposed function is reduction of lytic polysaccharide mono‐oxygenase for subsequent cellulose depolymerization. Electrons are transferred from FADH2 in the catalytic flavodehydrogenase domain of CDH to haem b in a mobile cytochrome domain, which acts as a mediator and transfers electrons towards the active site of lytic polysaccharide mono‐oxygenase to activate oxygen. This vital role of the cytochrome domain is little understood, e.g. why do CDHs exhibit different pH optima and rates for inter‐domain electron transfer (IET)? This study uses kinetic techniques and docking to assess the interaction of both domains and the resulting IET with regard to pH and ions. The results show that the reported elimination of IET at neutral or alkaline pH is caused by electrostatic repulsion, which preven...
In this article we describe production and characterisation of mutant pyranose dehydrogenase – an... more In this article we describe production and characterisation of mutant pyranose dehydrogenase – an excellent enzyme for fabrication of enzyme-based biosensors and bioanodes.
The search for an enzyme as a reagent for selective bioanalytical detection of the neurotoxic ami... more The search for an enzyme as a reagent for selective bioanalytical detection of the neurotoxic amino acid, β-N-oxalyl L-alpha, β-diaminopropionic acid, β-ODAP (found in grass pea, Lathyrus sativus) led to its redox catalytic reaction by glutamate oxidase (GluOx). Homogeneous kinetic studies and an immobilized GluOx reactor-based flow-injection assay were initially made for beta-ODAP with small immobilized GluOx/catalase glutamate destroying prereactors. The method was applied to examine the toxin content in processed grass pea. The kinetics and the equilibrium of the thermal isomerization of β-ODAP to the nontoxic isomer α-ODAP established that GluOx is specific to the neurotoxin. The first ever GluOx-based amperometric biosensor for liquid chromatography (LC) detection was reported in 1997. This biosensor coupled with a refractive index detector improved LC performance. The most recent work with GluOx resulted in MnO2-based screen-printed amperometric biosensor, with offline elimina...
The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganes... more The electrochemistry of the ligninolytic redox enzymes, which include lignin peroxidase, manganese peroxidase and laccase and possibly also cellobiose dehydrogenase, is reviewed and discussed in conjunction with their basic biochemical characteristics. It is shown that long‐range electron transfer between these enzymes and electrodes can be established and their ability to degrade lignin through a direct electron transfer mechanism is discussed.
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