Dioxygenase copper complexes

NON-IRON MODEL STUDIES ON DIOXYGENASES 4.6. Copper Complexes... 

Peptide Amidation by Metal Complexes. 16.6 A COPPER DIOXYGENASE ENZYME... 

Mechanisms have rarely been elucidated unambiguously, especially for easily oxidizable ligands, where alternative explanations are difficult to rule out. In fact, closer examination of some of these so-called transfer reactions has revealed that free hydrogen peroxide is the oxidant (55). Moreover, this type of reaction is restricted to the heavier transition metals which form Jt-type peroxo complexes (7) with dioxygen and are therefore scarcely models for the iron- and copper-containing dioxygenases. 

Nearly all dioxygenases contain iron or copper, which in most cases is a direct constituent of the enzyme protein. Iron may also be part of ferroprotoporphyrin IX (heme, D 10.1 Table 15). The metal activates the oxygen linked to the enzyme, a process which is associated with polarization of the complex. In the case of the iron-containing enzymes this may be formulated as follows ... 

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