How does the push/pull effect of the axial ligand influence the catalytic properties of Compound I of catalase and cytochrome P450?

Modification of the heme active site to increase the peroxidase activity of thermophilic cytochrome P450: A rational approach

“…The present observation that incorporation of the hydrogen bonding residues enhances the rates of the catalysis, possibly indicate that the H 2 O 2 bound heme is indeed involved in the process. Heterolytic cleavage of the peroxide complex by the 'Push-Pull' mechanism is the accepted pathway of formation of the ferryl heme species of the compound I of the peroxidases, which seems to be obeyed in the present case also [54,55]. The results in the present studies suggest that the change in the values of the k cat on introduction of hydrogen bonding residues (histidine or glutamine) at Leu80 site possibly arises due to facilitation of heterolytic cleavage of the O-O bond in the peroxide complex of the iron of heme.…”

Catalases versus peroxidases: DFT investigation of H2O2 oxidation in models systems and implications for heme protein engineering

“…De Visser and coworkers [56] compared the reactivity of catalase and peroxidase models towards propene. The first step of the hydroxylation of propene, i.e.…”

How Does the Axial Ligand of Cytochrome P450 Biomimetics Influence the Regioselectivity of Aliphatic versus Aromatic Hydroxylation?

“…[22,27] However, this is not always the rule, as a concerted reaction mechanism was also found, for example, for a catalase CpdI model, which indicates that the lifetime of the radical is ultrashort and will lead to products almost instantaneously. [28] As can be seen from Figure 2, the axial ligand has little effect on the exothermicities of benzylic or phenylic hydroxylation since the relative energies between CpdI and the product complexes are virtually the same regardless of the axial ligand. This is as expected, since essentially the same reaction is catalysed.…”