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- Title
Mechanism of protein oxidative damage that is coupled to long-range electron transfer to high-valent haems.
- Authors
Zhongxin Ma; Williamson, Heather R.; Davidson, Victor L.
- Abstract
In the absence of its substrate, the auto-reduction of the high-valent bis-Fe(IV) state of the dihaem enzyme MauG is coupled to oxidative damage of a methionine residue. Transient kinetic and solvent isotope effect studies reveal that this process occurs via two sequential long-range electron transfer (ET) reactions from methionine to the haems. The first ET is coupled to proton transfer (PT) to the haems from solvent via an ordered water network. The second ET is coupled to PT at the methionine site and occurs during the oxidation of the methionine to a sulfoxide. This process proceeds via Compound I- and Compound II-like haem intermediates. It is proposed that the methionine radical is stabilized by a two-centre three-electron (2c3e) bond. This provides insight into how oxidative damage to proteins may occur without direct contact with a reactive oxygen species, and how that damage can be propagated through the protein.
- Subjects
CHARGE exchange; OXIDATION-reduction reaction; PROTON transfer reactions; METHIONINE sulfoxide; OXIDATIVE dehydrogenation; REACTIVE oxygen species; METHIONINE
- Publication
Biochemical Journal, 2016, Vol 473, Issue 12, p1769
- ISSN
0264-6021
- Publication type
Article
- DOI
10.1042/BCJ20160047