Peroxidase catalytic cycles, scheme

Scheme 5 Side reactions in the peroxidase catalytic cycle... 

Figure 2-9. Reaction scheme for the complete catalytic cycle in glutathione peroxidase (left). Numbers represent calculated reaction barriers using the active-site model. The detailed potential energy diagram for the first elementary reaction, (E-SeH) + H2O2 - (E-SeOH) + H2O, calculated using both the active-site (dashed line) and ONIOM model (grey line) is shown to the right (Adapted from Prabhakar et al. [28, 65], Reprinted with permission. Copyright 2005, 2006 American Chemical Society.)...

Fig. 1 Generic scheme of the catalytic cycle of peroxidases (taken from [24])...

Scheme 1 Catalytic cycle of peroxidase. L ligand, R reduced compound. (Reprinted with permission from Gross et al. [9]. 2001, American Chemical Society)...

In the peroxidase reaction, Compound I is reduced to the Fe111 resting state via Compound II in two consecutive one-electron transfer steps which results in the formation of two substrate radicals (path B in Scheme 2.11). With respect to the whole catalytic cycle, this behavior can be described by the following equation ... 

Scheme 2.14 Catalytic cycle of peroxidase-catalyzed sulfoxidations.

As for other peroxidases, a high-valent iron-oxo entity associated with a porphyrin 7r-radical-cation, Cpd I, is generated by the addition of hydrogen peroxide (see Scheme 3 for the catalytic cycle of LiP). This green compound (Soret band at 408 nm) has UV-visible and EPR characteristics similar to that of HRP-Cpd 1. ... 

Scheme 3 Proposed catalytic cycle of heme peroxidases...

Peroxidases catalyze the two-electron reduction of H2O2 (or organic peroxides) to H2O (or alcohols) by electron-transfer proteins or small organic reagents. A general catalytic cycle for the heme-containing enzymes is shown in Scheme 7. 

Scheme 2.174 Catalytic cycles of heme-dependent peroxidases...

Successful work with peroxidases requires knowledge about the possible side reactions in the catalytic cycle. The most important are shown in Scheme 5 [39]. The pathway from 18 to 21 covers the normal catalytic cycle. If the local phenol concentration is too low and/or the local concentration of hydrogen peroxide is too high, compound I is converted into an intermediate (Scheme 5, 23) [39,69]. This intermediate can follow three different paths of decomposition. First it can react back to the na-... 

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