Direct electron transfer of catalase

Biosensors based on direct electron transfer of catalase... 

Due to high biocompability of NiOx nanoparticles, we investigate the direct electron transfer processes of immobilized hemoglobin and catalase onto glassy carbon electrodes modified with nickel oxide nanosize materials [255,256],... 

There have been few direct electrochemical studies of peroxidase and catalase due to the highly irreversible nature of these electrode reactions. Horseradish peroxidase was found to be electroinactive at the dropping mercury electrode. Tarasevich and co-workers observed a cyclic voltam-metric response for the electron transfer of horseradish peroxidase at an amalgamated gold electrode. However, this response was ascribed to the disulfide bonds of the protein at neutral pH and not to the heme group. No response was detected at pyrolytic graphite electrodes. ... 

As with AuNP electrodes, electrodes that consist of collections of CNTs prepared by adsorption of SWCNTs or MWCNTs on a conductive substrate or CNT electrodes prepared by screen printing of CNT-based conductive inks °° have been used as platforms for observing direct electron transfer in proteins, such as cyt and catalase. " CNT electrodes... 

The direct electron transfer from the coenzyme NADH to the electrode can be facilitated using organic conducting salts such as NMP+TCNQ" (see 3.3.l.f). These salts reduce the cofactor redox potential required, which limits any interference phenomena and fouling up of the electrodes [43]. These problems can also be overcome using an electrode with a hydrophobic membrane (p02 electrode) on which alcohol oxidase and catalase [170] can be immobilized. These enzymes catalyse the following reactions ... 

Moreover, it has been demonstrated that CNTs promote the direct electrochemistry of enzymes. Dong and coworkers have reported the direct electrochemistry of microperoxidase 11 (MP-11) using CNT-modified GC electrodes [101] and layer-by-layer self-assembled films of chitosan and CNTs [102], The immobilized MP-11 has retained its bioelectrocatalytic activity for the reduction of H202 and 02, which can be used in biosensors or biofuel cells. The direct electrochemistry of catalase at the CNT-modified gold and GC electrodes has also been reported [103-104], The electron transfer rate involving the heme Fe(III)/Fe(II) redox couple for catalase on the CNT-modified electrode is much faster than that on an unmodified electrode or other... 

The generation of reactive catalase in its oxidized stage can also be achieved by direct electrochemical oxidation (transfer of electrons from ferric protoporphyrin IX to the electrode). Thus, catalase immobilized on graphite electrodes has been used for the hydrogen peroxide-free oxidation of phenol [168l... 

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