TY - JOUR
T1 - Two-Color Valence-to-Core X-ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase
AU - Martinie, Ryan J.
AU - Blaesi, Elizabeth J.
AU - Bollinger, J. Martin
AU - Krebs, Carsten
AU - Finkelstein, Kenneth D.
AU - Pollock, Christopher J.
N1 - Publisher Copyright:
© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/9/24
Y1 - 2018/9/24
N2 - 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.
AB - 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.
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U2 - 10.1002/anie.201807366
DO - 10.1002/anie.201807366
M3 - Article
C2 - 30075052
AN - SCOPUS:85052936302
SN - 1433-7851
VL - 57
SP - 12754
EP - 12758
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 39
ER -