Evidence for Two Ferryl Species in Chloroperoxidase 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-II suggests the presence of two distinct ferryl species in an ∼70:30 ratio. Density functional calculations and cryogenic reduction...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2006-05, Vol.128 (18), p.6147-6153
Main Authors: Stone, Kari L, Hoffart, Lee M, Behan, Rachel K, Krebs, Carsten, Green, Michael T
Format: Article
Language:English
Subjects:
Biological and medical sciences
Chloride Peroxidase - chemistry
Electronic structure
Fundamental and applied biological sciences. Psychology
Iron - chemistry
Molecular biophysics
Quantum Theory
Spectroscopy, Mossbauer
Structure in molecular biology
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Summary:Using a combination of density functional calculations and Mössbauer spectroscopy, we have examined chloroperoxidase compound II (CPO-II). The Mössbauer spectrum of CPO-II 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-II's visible absorption spectrum, which shows no change over the enzyme's range of pH stability.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja057876w