A Mn II Mn III -Peroxide Complex Capable of Aldehyde Deformylation

Adriana M. Magherusan, Subhasree Kal, Daniel N. Nelis, Lorna M. Doyle, Erik R. Farquhar, Lawrence Que, Aidan R. McDonald

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Abstract

Ribonucleotide reductases (RNRs) are essential enzymes required for DNA synthesis. In class Ib Mn 2 RNRs superoxide (O 2 .− ) was postulated to react with the Mn II 2 core to yield a Mn II Mn III -peroxide moiety. The reactivity of complex 1 ([Mn II 2 (O 2 CCH 3 ) 2 (BPMP)](ClO 4 ), where HBPMP=2,6-bis{[(bis(2-pyridylmethyl)amino]methyl}-4-methylphenol) towards O 2 .− was investigated at −90 °C, generating a metastable species, 2. The electronic absorption spectrum of 2 displayed features (λ max =440, 590 nm) characteristic of a Mn II Mn III -peroxide species, representing just the second example of such. Electron paramagnetic resonance and X-ray absorption spectroscopies, and mass spectrometry supported the formulation of 2 as a Mn II Mn III -peroxide complex. Unlike all other previously reported Mn 2 -peroxides, which were unreactive, 2 proved to be a capable oxidant in aldehyde deformylation. Our studies provide insight into the mechanism of O 2 -activation in Class Ib Mn 2 RNRs, and the highly reactive intermediates in their catalytic cycle.

Original languageEnglish (US)
Pages (from-to)5718-5722
Number of pages5
JournalAngewandte Chemie - International Edition
Volume58
Issue number17
DOIs
StatePublished - Apr 16 2019

Bibliographical note

Funding Information:
This publication has emanated from research supported by the Irish Research Council (IRC) under Grant Numbers GOIPG/2014/942 to A.M. and GOIPG/2017/525 to D.N. Research in the McDonald lab is supported in part by the European Union (ERC-2015-STG-678202) and research grants Science Foundation Ireland (SFI/15/RS-URF/3307, SFI/17/RS-EA/3470). Support for this research in the Que lab has been provided by the US National Institutes of Health (GM38767). XAS measurements benefited from support of SSRL by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515, as well as support of the SSRL Structural Molecular Biology Program through the DOE Office of Biological and Environmental Research and the National Institutes of Health (P41-GM-103393). E.R.F. is supported by NIH grant P30-EB-009998.

Publisher Copyright:
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Keywords

  • Mn Mn -peroxide
  • aldehyde deformylation
  • nucleophilic reactivity
  • ribonucleotide reductases
  • superoxide activation

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