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Tyrosine or Tryptophan? Modifying a Metalloradical Catalytic Site by Removal of the Cys–Tyr Cross‐Link in the Galactose 6‐Oxidase Homologue GlxA

Chaplin, AK and Bernini, C and Sinicropi, A and Basosi, R and Worrall, JAR and Svistunenko, DA (2017) 'Tyrosine or Tryptophan? Modifying a Metalloradical Catalytic Site by Removal of the Cys–Tyr Cross‐Link in the Galactose 6‐Oxidase Homologue GlxA.' Angewandte Chemie International Edition, 129 (23). 6602 - 6606. ISSN 1433-7851

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Abstract

The concerted redox action of a metal ion and an organic cofactor is a unique way to maximize the catalytic power of an enzyme. An example of such synergy is the fungal galactose 6-oxidase, which has inspired the creation of biomimetic copper oxidation catalysts. Galactose 6-oxidase and its bacterial homologue, GlxA, possess a metalloradical catalytic site that contains a free radical on a covalently linked Cys?Tyr and a copper atom. Such a catalytic site enables for the two-electron oxidation of alcohols to aldehydes. When the ability to form the Cys?Tyr in GlxA is disrupted, a radical can still be formed. Surprisingly, the radical species is not the Tyr residue but rather a copper second-coordination sphere Trp residue. This is demonstrated through the introduction of a new algorithm for Trp-radical EPR spectra simulation. Our findings suggest a new mechanism of free-radical transfer between aromatic residues and that the Cys?Tyr cross-link prevents radical migration away from the catalytic site.

Item Type: Article
Uncontrolled Keywords: copper-radical oxidases; EPR spectra simulations; through-protein radical transfer; TRSSA; Tyr?Cys motif
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Life Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 08 Jun 2017 15:41
Last Modified: 02 Sep 2019 22:15
URI: http://repository.essex.ac.uk/id/eprint/19603

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