Dehaloperoxidase (DHP) from the marine worm Amphitrite ornata is a hemoglobin with dual physiological role.  Its known functions are as a respiratory protein and as peroxidase dehalogenating 2,4,6-tribromophenol, a defense chemical.  The active site of DHP is a heme center, which is coordinated by a histidine residue in the proximal position and exhibits an internal distal cavity.  Purified recombinant 57Fe-DHP samples were studied with M�ssbauer spectroscopy in order to obtain a characterization of the enzyme in the resting state and throughout its catalytic cycle.  Rapid mixing of ferric DHP and H2O2 yielded an FeIV-oxo state, similar to Compound II.  The ferryl, ferrous and two distinct ferric states were studied with variable-field variable-temperature Mossbauer spectroscopy, in search of electronic features of the heme that might correlate with the dual function.  Elucidation of the electronic structure and mechanism is of this peroxidase is of general interest for its fundamental importance and for applications to environmental remediation.

M�ssbauer studies of the ferryl, ferrous, and ferric states of the dehaloperoxidase from Amphitrite ornata

248th National Meeting (2014)

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