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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

Lucic, Marina and Svistunenko, Dimitri and Wilson, Michael and Chaplin, Amanda and Davy, Bradley and Ebrahim, Ali and Axford, Danny and Tosha, Takehiko and Sugimoto, Hiroshi and Owada, Shigeki and Dworkowski, Florian and Tews, Ivo and Owen, Robin and Hough, Michael and Worrall, Jonathan AR (2020) '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.' Angewandte Chemie International Edition. ISSN 1433-7851

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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.

Item Type: Article
Uncontrolled Keywords: bioinorganic, heme proteins, peroxidase, Structural biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Elements
Date Deposited: 07 Sep 2020 07:00
Last Modified: 29 Sep 2020 16:15
URI: http://repository.essex.ac.uk/id/eprint/28653

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