Mono-electronic peroxidase-catalyze

However, meta hydroxyl groups (in C3 or in C5) of stilbenes could not be directly oxidized by peroxidase [143], so the M03 (or Mos) mesomer cannot arise directly fi"om a mono-electronic peroxidase-catalyzed oxidation in C3 (or in C5). The M03 (or Mos) mesomer, like Mp, could be formed by... 

Perhaps the most well-known peroxidase-catalyzed reactions are those involving electron transfer, in which an aromatic substrate is oxidized in a mono-electronic oxidation up to its mono-radical, Eq. (1), which is capable of participating further in a variety of non-enzymatic reactions such as disproportionation, polymerization and electron transfer. These types of reactions are very common during the peroxidase-catalyzed oxidation of phenols and, in some cases, during the oxidation of alkaloids. For example, peroxidase is capable of dimerizing jatrorrhizine (IV) to 4,4 -bis-jatrorrhizine (V) in the presence of H2O2 (Scheme III) [50]. 

As is the case for other phenols, the peroxidase-catalyzed oxidation of (+)-catechin involves a one-electron oxidation [36] and yields unstable mono-radical species, R ... 

The coupling reaction by which the aromatic group from one residue of mono- or diiodotyrosine is joined in ether linkage with a second residue is also catalyzed readily by peroxidases. One dehydroalanine residue is formed for each molecule of hormone released.108 A possible mechanism involves formation of an electron-deficient radical, which can undergo (3 elimination to produce a dehydroalanine residue and an aromatic radical. The latter could couple with a second radical to form triiodothyronine or thyroxine. However, as depicted in Eq. 25-6, the radical coupling may occur prior to chain cleavage. While P elimination (pathway... 

There are many oxidoreductase enzymes, i.e. enzymes able to catalyze redox reactions oxidases, dehydrogenases, peroxidases, superoxide dismutases and finally the mono- and dioxygenases. All of them contain active sites that are able to transfer electrons using mediators or redox catalysts that can be classified into four categories ... 

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