SPIN STATE CHARACTERIZATION OF METALLOEMZYMES VIA X-RAY EMISSION SPECTROSCOPY

Emamian, Sahand

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Description

Title

SPIN STATE CHARACTERIZATION OF METALLOEMZYMES VIA X-RAY EMISSION SPECTROSCOPY

Author(s)

Emamian, Sahand

Contributor(s)

• Davis, Katherine M
• Pushkar, Yulia N
• Maximova, Olga
• McWhorter, Kirklin L
• Purohit, Vatsal
• Ireland, Kendra A

Issue Date

2023-06-20

Keyword(s)

Mini-symposium: Spectroscopy at Large-scale Facilities

Abstract

Enzyme reactivity is often enhanced by changes in oxidation state, spin state, and metal-ligand covalency of associated metallocofactors. The development of spectroscopic methods for studying these processes coincidentally with structural rearrangements is essential for elucidating metalloenzyme mechanisms. Herein, we demonstrate the feasibility of collecting X-ray emission spectra of metalloenzyme crystals at a third-generation synchrotron source. In particular, we report the development of a von Hamos spectrometer for the collection of Fe Kβ emission optimized for analysis of dilute biological samples. We further showcase the application of this high-resolution, "DIY" mini-spectrometer in crystals of the immunosuppressive heme-dependent enzyme indoleamine 2,3-dioxygenase (IDO). Spectra obtained from reference compounds were compared to catalytically-relevant states of IDO via integrated absolute difference analysis to determine their spin numbers. Complementary density functional calculations assessing covalency support our spectroscopic analysis and identify active site conformations that correlate to high- and low-spin systems. These experiments validate the suitability of an X-ray emission approach for determining spin states of previously uncharacterized metalloenzyme reaction intermediates.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122699

DOI

https://doi.org/10.15278/isms.2023.7252

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