First report on electrocatalytic oxidation of oxytetracycline by horse radish peroxidase: Application in developing a biosensor to oxytetracycline determination

Electrocatalytic Properties of Immobilized Heme Proteins: Basic Principles and Applications

“…In a short time scale, typical of a CV measurement, the protein transfers electrons with the electrode without diffusing through the film. [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] Substrate turn-over or electron transfer rate can heavily affect the kinetics of biocatalyzed reactions. [42][43][44][45][46][47] In electron-hopping mechanism, the ET from or to the single protein molecule can be extended sequentially from the electrode surface to protein molecules far away from the surface by successive electron exchange (hopping) among adjacent protein molecules in the films (see Figure 1 in ref.…”

“…[42][43][44][45][46][47] In electron-hopping mechanism, the ET from or to the single protein molecule can be extended sequentially from the electrode surface to protein molecules far away from the surface by successive electron exchange (hopping) among adjacent protein molecules in the films (see Figure 1 in ref. [5,33,[56][57][58][59][60][61][62][63][64][65][66] Electrocatalysis based on direct electron transfer (DET) is yielded by several enzymes regardless of whether or not the redox center coincides with the catalytic center. The electron transfer process in the film, however, must be accompanied by the diffusion of counterions from or to the external solution to compensate the charge acquired by the film due to the electron transfer.…”

“…[15,26,29,31] Higher surface concentration of enzyme active sites yields higher rates of substrate turn-over and therefore higher currents: for this reason, small enzymes or mutated ET proteins (which are in general much smaller than enzymes), would be better suited to electrocatalysis as they allow for more active sites per unit electrode surface. [56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] Substrate turn-over or electron transfer rate can heavily affect the kinetics of biocatalyzed reactions. The electrocatalytic performance, however, can also be conditioned by the conductivity and dispersion state of the electrodic material.…”

“…High-surface carbon materials, nanoparticles and metal oxides have been extensively used for this purpose and found effective to enhance electrical conductivity, increase dispersion and, ultimately, improve the electrochemical efficiency of the bioelectrocatalytic processes. [5,33,[56][57][58][59][60][61][62][63][64][65][66] Electrocatalysis based on direct electron transfer (DET) is yielded by several enzymes regardless of whether or not the redox center coincides with the catalytic center. [2,15,29,31] An alternative procedure to facilitate ET between the redox enzyme and the electrode is to use redox mediators.…”

“…Peroxidases were adsorbed on organic (lypopolissaccaride, polyaniline, DNA, glutaraldehyde) [158][159][160] or inorganic (titanium or manganese oxides) [161,162] components or directly included in carbon nanotubes or nanoparticles. [60,145,163] Peroxidases show high versatility and good analytical responses (low detection limit and large linear range) towards hydroperoxides also under severe conditions like high temperatures. [164] The significant variability of their reduction potentials (À 0.2 V � À 0.4 V) when adsorbed on a surface depends on the procedure used for enzyme immobilization.…”