title: Unusual C=C bond isomerization of an α,β-unsaturated γ-butyrolactone catalysed by flavoproteins from the old yellow enzyme family.
abstract: An unexpected, redox-neutral C=C bond isomerization of a γ-butyrolactone bearing an exo-methylene unit to the thermodynamically more favoured endo isomer (k(cat) =0.076 s(-1) ) catalysed by flavoproteins from the Old Yellow Enzyme family was discovered. Theoretical calculations and kinetic data support a mechanism through which the isomerization proceeds through FMN-mediated hydride addition onto exo-Cβ, followed by hydride abstraction from endo-Cβ', which is in line with the well-established C=C bond bioreduction of OYEs. This new isomerase activity enriches the catalytic versatility of ene-reductases.
authors.affiliation: Organic & Bioorganic Chemistry, Department of Chemistry, University of Graz, Heinrichstrasse 28, 8010 Graz, Austria.
authors.forename: Katharina
authors.initials: K
authors.lastname: Durchschein
authors.forename: Silvia
authors.initials: S
authors.lastname: Wallner
authors.forename: Peter
authors.initials: P
authors.lastname: Macheroux
authors.forename: Klaus
authors.initials: K
authors.lastname: Zangger
authors.forename: Walter M F
authors.initials: WM
authors.lastname: Fabian
authors.forename: Kurt
authors.initials: K
authors.lastname: Faber
mesh_terms: D015107:4-Butyrolactone / Q000096:biosynthesis* / Q000737:chemistry; D055162:Biocatalysis; D005420:Flavoproteins / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D015394:Molecular Structure; D009252:NADPH Dehydrogenase / Q000737:chemistry / Q000145:classification / Q000378:metabolism*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D005420:Flavoproteins; D009252:NADPH Dehydrogenase; D015107:4-Butyrolactone