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Chembiochem. 2018 Jan 4;19(1):53-57. doi: 10.1002/cbic.201700594. Epub 2017 Dec 12.

Flavin-N5 Covalent Intermediate in a Nonredox Dehalogenation Reaction Catalyzed by an Atypical Flavoenzyme.

Author information

1
Department of Biochemistry, Virginia Tech, 360 West Campus Drive, Blacksburg, Virginia, 24061, USA.
2
Department of Biochemistry, University of Missouri, Columbia, Missouri, 65211, USA.
3
Department of Chemistry, University of Missouri, Columbia, Missouri, 65211, USA.

Abstract

The flavin-dependent enzyme 2-haloacrylate hydratase (2-HAH) catalyzes the conversion of 2-chloroacrylate, a major component in the manufacture of acrylic polymers, to pyruvate. The enzyme was expressed in Escherichia coli, purified, and characterized. 2-HAH was shown to be monomeric in solution and contained a non-covalent, yet tightly bound, flavin adenine dinucleotide (FAD). Although the catalyzed reaction was redox-neutral, 2-HAH was active only in the reduced state. A covalent flavin-substrate intermediate, consistent with the flavin-acrylate iminium ion, was trapped with cyanoborohydride and characterized by mass spectrometry. Small-angle X-ray scattering was consistent with 2-HAH belonging to the succinate dehydrogenase/fumarate reductase family of flavoproteins. These studies establish 2-HAH as a novel noncanonical flavoenzyme.

KEYWORDS:

covalent adduct; dehalogenation; flavin; iminium adduct; non-redox reactions

PMID:
29116682
DOI:
10.1002/cbic.201700594
[Indexed for MEDLINE]

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