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Evidence for Two Ferryl Species in Chioroperoxidase Compound II.

Using a combination of density functional calculations and Mössbauer spectroscopy, we have examined chloroperoxidase compound II (CPO-II). The Mössbauer spectrum of CPO-ll suggests the presence of two distinct ferryl species in an ~70:30 ratio. Density functional calculations and cryogenic reduction...

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Published in:Journal of the American Chemical Society Vol. 128; no. 18; pp. 6147 - 6154
Main Authors: Stone, Karl L., Hoffart, Lee M., Behan, Rachel K., Krebs, Carsten, Green, Michael T.
Format: Article
Published: American Chemical Society 5/10/2006
Subjects:
Peroxidase
Iron compounds
Mössbauer spectroscopy
Chlorine compounds
Density functionals
Hydrogen-ion concentration
Online Access:View this record in EBSCOhost
Summary:Using a combination of density functional calculations and Mössbauer spectroscopy, we have examined chloroperoxidase compound II (CPO-II). The Mössbauer spectrum of CPO-ll suggests the presence of two distinct ferryl species in an ~70:30 ratio. Density functional calculations and cryogenic reduction and annealing experiments allow us to assign the major species as an Fe(IV)OH intermediate. The Mössbauer parameters of the minor component are indicative of an authentic iron(IV)oxo species, but we have found the 70:30 ratio to be pH invariant. The unchanging ratio of component concentrations is in agreement with CPO-ll's visible absorption spectrum, which shows no change over the enzyme's range of pH stability.