Room temperature X-ray absorption spectroscopy of metalloenzymes with drop-on-demand sample delivery at XFELs.

Isabel Bogacz Hiroki Makita Philipp S Simon Miao Zhang Margaret D Doyle Ruchira Chatterjee Thomas Fransson Clemens Weninger Franklin D Fuller Leland B Gee Takahiro Sato Matthew H Seaberg Roberto Alonso Mori Uwe Bergmann Vittal K Yachandra Jan F Kern Junko Yano

Published in: Pure and applied chemistry. Chimie pure et appliquee (2023)

X-ray crystallography and X-ray spectroscopy using X-ray free electron lasers plays an important role in understanding the interplay of structural changes in the protein and the chemical changes at the metal active site of metalloenzymes through their catalytic cycles. As a part of such an effort, we report here our recent development of methods for X-ray absorption spectroscopy (XAS) at XFELs to study dilute biological samples, available in limited volumes. Our prime target is Photosystem II (PS II), a multi subunit membrane protein complex, that catalyzes the light-driven water oxidation reaction at the Mn 4 CaO 5 cluster. This is an ideal system to investigate how to control multi-electron/proton chemistry, using the flexibility of metal redox states, in coordination with the protein and the water network. We describe the method that we have developed to collect XAS data using PS II samples with a Mn concentration of <1 mM, using a drop-on-demand sample delivery method.

Keyphrases