Bacterial cytochrome c peroxidases, exemplified by the enzyme from Pseudomonasaeruginosa, contain a high potentialheme, which accepts electrons and subsequently transfers them to a lowpotential heme, where substrate binds. In order for catalysis the HP heme mustfirst undergo a one-electron reduction to the ferrous state. This causes astructural rearrangement of the LP heme so H2O2 can bind.Sequence analysis has revealed a unique bacterial peroxidase from Escherichiacoli which contains a thirdheme binding motif in the N-terminal domain. Kinetic assays have shown that theputative Ec cytochrome c peroxidase does indeed demonstrated peroxidaseactivity, with a Km = 8 �M. Unlike the Pa enzyme Ec CcP does not requirepre-reduction of the high potential heme, nor inclusion of excess Ca2+.Electronic absorption and EPR measurements have also revealed unique featurespotentially associated with the third heme, whose function remains unknown.

Electrochemical
investigation of cytochrome <i>c</i> peroxidase from <i>Escherichia coli</i>

239th National Meeting (2010)

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Electrochemical investigation of cytochrome c peroxidase from Escherichia coli