Epoxide hydrolysis as a model system for understanding flux through a branched reaction scheme
Janfalk Carlsson, Åsa ; Bauer, Paul ; Dobritzsch, Doreen ; Kamerlin, Shina C L LU
and Widersten, Mikael
(2018)
In IUCrJ
5(Pt 3).
p.269-282
- Abstract
The epoxide hydrolase StEH1 catalyzes the hydrolysis of trans-methylstyrene oxide to 1-phenyl-propane-1,2-diol. The (S,S)-epoxide is exclusively transformed into the (1R,2S)-diol, while hydrolysis of the (R,R)-epoxide results in a mixture of product enantiomers. In order to understand the differences in the stereoconfigurations of the products, the reactions were studied kinetically during both the pre-steady-state and steady-state phases. A number of closely related StEH1 variants were analyzed in parallel, and the results were rationalized by structure-activity analysis using the available crystal structures of all tested enzyme variants. Finally, empirical valence-bond simulations were performed in order to provide additional insight... (More)
The epoxide hydrolase StEH1 catalyzes the hydrolysis of trans-methylstyrene oxide to 1-phenyl-propane-1,2-diol. The (S,S)-epoxide is exclusively transformed into the (1R,2S)-diol, while hydrolysis of the (R,R)-epoxide results in a mixture of product enantiomers. In order to understand the differences in the stereoconfigurations of the products, the reactions were studied kinetically during both the pre-steady-state and steady-state phases. A number of closely related StEH1 variants were analyzed in parallel, and the results were rationalized by structure-activity analysis using the available crystal structures of all tested enzyme variants. Finally, empirical valence-bond simulations were performed in order to provide additional insight into the observed kinetic behaviour and ratios of the diol product enantiomers. These combined data allow us to present a model for the flux through the catalyzed reactions. With the (R,R)-epoxide, ring opening may occur at either C atom and with similar energy barriers for hydrolysis, resulting in a mixture of diol enantiomer products. However, with the (S,S)-epoxide, although either epoxide C atom may react to form the covalent enzyme intermediate, only the pro-(R,S) alkylenzyme is amenable to subsequent hydrolysis. Previously contradictory observations from kinetics experiments as well as product ratios can therefore now be explained for this biocatalytically relevant enzyme.
(Less)
- author
- Janfalk Carlsson, Åsa
; Bauer, Paul
; Dobritzsch, Doreen
; Kamerlin, Shina C L
LU
and Widersten, Mikael
- publishing date
- 2018-05-01
- type
- Contribution to journal
- publication status
- published
- in
- IUCrJ
- volume
- 5
- issue
- Pt 3
- pages
- 14 pages
- publisher
- International Union of Crystallography
- external identifiers
-
- pmid:29755743
- scopus:85046534973
- ISSN
- 2052-2525
- DOI
- 10.1107/S2052252518003573
- language
- English
- LU publication?
- no
- id
- 2d2179e5-885a-4b89-a459-c702e48c1a6f
- date added to LUP
- 2025-01-11 21:12:17
- date last changed
- 2025-01-18 03:18:29
@article{2d2179e5-885a-4b89-a459-c702e48c1a6f,
abstract = {{<p>The epoxide hydrolase StEH1 catalyzes the hydrolysis of trans-methylstyrene oxide to 1-phenyl-propane-1,2-diol. The (S,S)-epoxide is exclusively transformed into the (1R,2S)-diol, while hydrolysis of the (R,R)-epoxide results in a mixture of product enantiomers. In order to understand the differences in the stereoconfigurations of the products, the reactions were studied kinetically during both the pre-steady-state and steady-state phases. A number of closely related StEH1 variants were analyzed in parallel, and the results were rationalized by structure-activity analysis using the available crystal structures of all tested enzyme variants. Finally, empirical valence-bond simulations were performed in order to provide additional insight into the observed kinetic behaviour and ratios of the diol product enantiomers. These combined data allow us to present a model for the flux through the catalyzed reactions. With the (R,R)-epoxide, ring opening may occur at either C atom and with similar energy barriers for hydrolysis, resulting in a mixture of diol enantiomer products. However, with the (S,S)-epoxide, although either epoxide C atom may react to form the covalent enzyme intermediate, only the pro-(R,S) alkylenzyme is amenable to subsequent hydrolysis. Previously contradictory observations from kinetics experiments as well as product ratios can therefore now be explained for this biocatalytically relevant enzyme.</p>}},
author = {{Janfalk Carlsson, Åsa and Bauer, Paul and Dobritzsch, Doreen and Kamerlin, Shina C L and Widersten, Mikael}},
issn = {{2052-2525}},
language = {{eng}},
month = {{05}},
number = {{Pt 3}},
pages = {{269--282}},
publisher = {{International Union of Crystallography}},
series = {{IUCrJ}},
title = {{Epoxide hydrolysis as a model system for understanding flux through a branched reaction scheme}},
url = {{http://dx.doi.org/10.1107/S2052252518003573}},
doi = {{10.1107/S2052252518003573}},
volume = {{5}},
year = {{2018}},
}