Direct visualization of a Fe(IV)–OH intermediate in a heme enzyme

Kwon, H, Basran, J, Casadei, CM, Fielding, AJ, Schrader, TE, Ostermann, A, Devos, JM, Aller, P, Blakeley, MP, Moody, PCE and Raven, EL (2016) Direct visualization of a Fe(IV)–OH intermediate in a heme enzyme. Nature Communications, 7. ISSN 2041-1723

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Abstract

Catalytic heme enzymes carry out a wide range of oxidations in biology. They have in common a mechanism that requires formation of highly oxidized ferryl intermediates. It is these ferryl intermediates that provide the catalytic engine to drive the biological activity. Unravelling the nature of the ferryl species is of fundamental and widespread importance. The essential question is whether the ferryl is best described as a Fe(IV)=O or a Fe(IV)–OH species, but previous spectroscopic and X-ray crystallographic studies have not been able to unambiguously differentiate between the two species. Here we use a different approach. We report a neutron crystal structure of the ferryl intermediate in Compound II of a heme peroxidase; the structure allows the protonation states of the ferryl heme to be directly observed. This, together with pre-steady state kinetic analyses, electron paramagnetic resonance spectroscopy and single crystal X-ray fluorescence, identifies a Fe(IV)–OH species as the reactive intermediate. The structure establishes a precedent for the formation of Fe(IV)–OH in a peroxidase.

Item Type: Article
Uncontrolled Keywords: MD Multidisciplinary
Subjects: Q Science > QD Chemistry
Q Science > QH Natural history > QH301 Biology
Divisions: Pharmacy and Biomolecular Sciences
Publisher: Nature Publishing Group
Date of acceptance: 5 October 2016
Date of first compliant Open Access: 26 January 2018
Date Deposited: 26 Jan 2018 09:53
Last Modified: 04 Sep 2021 10:49
DOI or ID number: 10.1038/ncomms13445
URI: https://ljmu-9.eprints-hosting.org/id/eprint/7901
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