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Serial femtosecond zero dose crystallography captures a water‐free distal heme site in a dye‐decolourising peroxidase to reveal a catalytic role for an arginine in FeIV=O formation

DOI: 10.1002/anie.202008622 DOI Help

Authors: Marina Lucic (University of Essex) , Dimitri Svistunenko (University of Essex) , Michael Wilson (University of Essex) , Amanda Chaplin (University of Essex) , Bradley Davy (Diamond Light Source) , Ali Ebrahim (University of Essex) , Danny Axford (Diamond Light Source) , Takehiko Tosha (RIKEN Spring 8) , Hiroshi Sugimoto (RIKEN Spring 8) , Shigeki Owada (Japan Synchrotron Radiation Facility) , Florian Dworkowski (Paul Scherrer Institut) , Ivo Tews (University of Southampton) , Robin Owen (Diamond Light Source) , Michael Hough (University of Essex) , Jonathan A. R. Worrall (University of Essex)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: August 2020

Open Access Open Access

Abstract: Obtaining structures of intact redox states of metal centres derived from zero dose X‐ray crystallography can advance our mechanistic understanding of metalloenzymes. In dye‐decolourising heme peroxidases (DyPs), controversy exists regarding the mechanistic role of the distal heme residues, aspartate and arginine, in the heterolysis of peroxide to form the catalytic intermediate compound I (Fe IV =O and a porphyrin cation radical). Using serial femtosecond X‐ray (SFX) crystallography, we have determined the pristine structures of the Fe III and Fe IV =O redox states of a B‐type DyP. These structures reveal a water‐free distal heme site, which together with the presence of an asparagine, infer the use of the distal arginine as a catalytic base. A combination of mutagenesis and kinetic studies corroborate such a role. Our SFX approach thus provides unique insight into how the distal heme site of DyPs can be tuned to select aspartate or arginine for the rate enhancement of peroxide heterolysis.

Journal Keywords: bioinorganic; heme proteins; peroxidase; Structural biology

Subject Areas: Chemistry

Facility: SACLA; SLS