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Laboratory-Evolved Enzymes Provide Snapshots of the Development of Enantioconvergence in Enzyme-Catalyzed Epoxide Hydrolysis

DOI: 10.1002/cbic.201600330 DOI Help

Authors: Åsa Janfalk Carlsson (Uppsala University) , Paul Bauer (Uppsala University) , Doreen Dobritzsch (Uppsala University) , Mikael Nilsson (Uppsala University) , S. C. Lynn Kamerlin (Uppsala University) , Mikael Widersten (Uppsala University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chembiochem , VOL 17 , PAGES 1693 - 1697

State: Published (Approved)
Published: September 2016
Diamond Proposal Number(s): 11265 , 8492

Open Access Open Access

Abstract: Engineered enzyme variants of potato epoxide hydrolase (StEH1) display varying degrees of enrichment of (2R)-3-phenylpropane-1,2-diol from racemic benzyloxirane. Curiously, the observed increase in the enantiomeric excess of the (R)-diol is not only a consequence of changes in enantioselectivity for the preferred epoxide enantiomer, but also to changes in the regioselectivity of the epoxide ring opening of (S)-benzyloxirane. In order to probe the structural origin of these differences in substrate selectivity and catalytic regiopreference, we solved the crystal structures for the evolved StEH1 variants. We used these structures as a starting point for molecular docking studies of the epoxide enantiomers into the respective active sites. Interestingly, despite the simplicity of our docking analysis, the apparent preferred binding modes appear to rationalize the experimentally determined regioselectivities. The analysis also identifies an active site residue (F33) as a potentially important interaction partner, a role that could explain the high conservation of this residue during evolution. Overall, our experimental, structural, and computational studies provide snapshots into the evolution of enantioconvergence in StEH1-catalyzed epoxide hydrolysis.

Journal Keywords: enantioselectivity; epoxide hydrolysis; evolutionary snapshots; laboratory evolution; protein engineering

Subject Areas: Biology and Bio-materials, Chemistry

Instruments: I02-Macromolecular Crystallography , I03-Macromolecular Crystallography , I04-Macromolecular Crystallography

Other Facilities: European Synchrotron Radiation Facility