Two-Color Valence-to-Core X-ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase

Ryan J. Martinie, Elizabeth J. Blaesi, J. Martin Bollinger, Carsten Krebs, Kenneth D. Finkelstein, Christopher J. Pollock

Research output: Contribution to journalArticle

4 Scopus citations

Abstract

Proton transfer reactions are of central importance to a wide variety of biochemical processes, though determining proton location and monitoring proton transfers in biological systems is often extremely challenging. Herein, we use two-color valence-to-core X-ray emission spectroscopy (VtC XES) to identify protonation events across three oxidation states of the O2-activating, radical-initiating manganese–iron heterodinuclear cofactor in a class I-c ribonucleotide reductase. This is the first application of VtC XES to an enzyme intermediate and the first simultaneous measurement of two-color VtC spectra. In contrast to more conventional methods of assessing protonation state, VtC XES is a more direct probe applicable to a wide range of metalloenzyme systems. These data, coupled to insight provided by DFT calculations, allow the inorganic cores of the MnIVFeIV and MnIVFeIII states of the enzyme to be assigned as MnIV(μ-O)2FeIV and MnIV(μ-O)(μ-OH)FeIII, respectively.

Original languageEnglish (US)
Pages (from-to)12754-12758
Number of pages5
JournalAngewandte Chemie - International Edition
Volume57
Issue number39
DOIs
StatePublished - Sep 24 2018

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)

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