Two‐Color Valence‐to‐Core X‐ray Emission Spectroscopy Tracks Cofactor Protonation State in a Class I Ribonucleotide Reductase
Year: 2018
Type: article
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.
Language: English
Subfield: Radiation
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: Mechanisms of Radical Translocation in Class I Ribonucleotide Reductases, G3087285872, G3525367178, Mechanistic Determination of the Non-heme Iron Enzyme Hyoscyamine-6-hydroxylase, G5356207468, OPERATION OF CORNELL HIGH ENERGY SYNCHROTRON SOURCE (CHESS), Oxygen Activation and Radical Transfer in Ribonucleotide Reductase from Pathogens, Graduate Research Fellowship Program (GRFP)
OpenAlex ID: W2886567318