Rates of Oxidation of Phenols by Compound U of Horseradish Peroxidase and Lactoperoxidase and Their Dependence on the Redox Potentials
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Thyroid peroxidase selects the mechanism of either 1- or 2-electron oxidation of phenols, depending on their substituents.
Unlike lactoperoxidase and horseradish peroxidase, thyroid peroxidase catalyzed the oxidation of hydroquinone mostly by way of 2-electron transfer. This conclusion could be derived from three independent experiments: ESR measurements of p-benzosemiquinone, trapping the unpaired electron by cytochrome c, and spectrophotometric analysis of catalytic intermediates of the enzymes. The 1-electron fl...
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Horseradish peroxidase was encapsulated in calcium alginate for the purpose of phenol removal. Considering enzyme encapsulation efficiency, retention activity and enzyme leakage of the capsules, the best gelation condition was found to be 1 % w/v of sodium alginate solution and 5.5 % w/v of calcium chloride hexahydrate. Upon immobilization, pH profile of enzyme activity changes as it shows ...
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Myeloperoxidase, eosinophil peroxidase and lactoperoxidase are heme-containing oxidoreductases, which undergo a series of redox reactions. Though sharing functional and structural homology, reflecting their phylogenetic origin, differences are observed regarding their spectral features, substrate specificities, redox properties and kinetics of interconversion of the relevant redox intermediates...
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Lignin peroxidase oxidizes non-phenolic substrates by one electron to give aryl-cation-radical intermediates, which react further to give a variety of products. The present study investigated the possibility that other peroxidative and oxidative enzymes known to catalyse one-electron oxidations may also oxidize non-phenolics to cation-radical intermediates and that this ability is related to th...
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The steady state kinetic parameters Km and kcat for the oxidation of phenolic substrates by lignin peroxidase correlated with the presteady state kinetic parameters Kd and k for the reaction of the enzyme intermediate compound II with the substrates, indicating that the latter is the rate-limiting step in the catalytic cycle. ln Km and ln Kd values for phenolic substrates correlated with redox ...
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