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Evidence for a Proton‐Coupled Electron Transfer Mechanism in a Biomimetic System for Monoamine Oxidase B Catalysis
Author(s) -
Nakamura Akiko,
Latif Marwa Abdel,
Deck Paul A.,
Castagnoli Neal,
Tanko James M.
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201904634
Subject(s) - proton coupled electron transfer , chemistry , electron transfer , catalysis , deprotonation , monoamine oxidase , electron transport chain , combinatorial chemistry , stereochemistry , photochemistry , organic chemistry , enzyme , biochemistry , ion
Mechanistic studies with 5‐ethyl‐3‐methyllumiflavinium (Fl + ) perchlorate, a biomimetic model for flavoenzyme monoamine oxidase B (MAO‐B) catalysis, and the tertiary, allyl amine 1‐methyl‐4‐(1‐methyl‐1 H ‐pyrrol‐2‐yl)‐1,2,3,6‐tetrahydropyridine (MMTP) reveal that proton‐coupled electron transfer (PCET) may be an important pathway for MAO catalysis. The first step involves a single‐electron transfer (SET) leading to the free radicals Fl . and MMTP . , the latter produced by deprotonation of the initially formed and highly acidic MMTP .+ . Molecular oxygen (O 2 ) is found to play a hitherto unrecognized role in the early steps of the oxidation. MMTP and several structurally similar tertiary amines are the only tertiary amines oxidized by MAO, and their structural/electronic properties provide the key to understanding this behavior. A general hypothesis about the role of SET in MAO catalysis, and the recognition that PCET occurs with appropriately substituted substrates is presented.