Class Ib Ribonucleotide Reductases: Activation of a Peroxido-Mn II Mn III to Generate a Reactive Oxo-Mn III Mn IV Oxidant - Département de Chimie Moléculaire Accéder directement au contenu
Article Dans Une Revue Inorganic Chemistry Année : 2024

Class Ib Ribonucleotide Reductases: Activation of a Peroxido-Mn II Mn III to Generate a Reactive Oxo-Mn III Mn IV Oxidant

Lorna Doyle
  • Fonction : Auteur
Shuangning Xu
Erik R Farquhar
Aidan R Mcdonald

Résumé

In the postulated catalytic cycle of class Ib Mn2 ribonucleotide reductases (RNRs), a MnII2 core is suggested to react with superoxide (O2·–) to generate peroxido-MnIIMnIII and oxo-MnIIIMnIV entities prior to proton-coupled electron transfer (PCET) oxidation of tyrosine. There is limited experimental support for this mechanism. We demonstrate that [MnII2(BPMP)(OAc)2](ClO4) (1, HBPMP = 2,6-bis[(bis(2 pyridylmethyl)amino)methyl]-4-methylphenol) was converted to peroxido-MnIIMnIII (2) in the presence of superoxide anion that converted to (μ-O)(μ-OH)MnIIIMnIV (3) via the addition of an H+-donor (p-TsOH) or (μ-O)2MnIIIMnIV (4) upon warming to room temperature. The physical properties of 3 and 4 were probed using UV–vis, EPR, X-ray absorption, and IR spectroscopies and mass spectrometry. Compounds 3 and 4 were capable of phenol oxidation to yield a phenoxyl radical via a concerted PCET oxidation, supporting the proposed mechanism of tyrosyl radical cofactor generation in RNRs. The synthetic models demonstrate that the postulated O2/Mn2/tyrosine activation mechanism in class Ib Mn2 RNRs is plausible and provides spectral insights into intermediates currently elusive in the native enzyme.

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Chimie
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hal-04643496 , version 1 (10-07-2024)

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Lorna Doyle, Adriana Magherusan, Shuangning Xu, Kayleigh Murphy, Erik R Farquhar, et al.. Class Ib Ribonucleotide Reductases: Activation of a Peroxido-Mn II Mn III to Generate a Reactive Oxo-Mn III Mn IV Oxidant. Inorganic Chemistry, 2024, 63 (4), pp.2194-2203. ⟨10.1021/acs.inorgchem.3c04163⟩. ⟨hal-04643496⟩
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