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Figure 7
Calculated free-energy profiles for the StEH1-catalyzed hydrolysis of 1a bound in the preferred of the two binding modes shown in Fig. 2[link]. RS, TS1, ISalk, TS2 and ISTD indicate the Michaelis complex, the transition state for nucleophilic attack on the epoxide, the alkylenzyme intermediate, the transition state for the hydrolysis of this intermediate and the resulting tetrahedral intermediate, respectively. All values are averages over 30 individual trajectories at each reacting state. Shown here are the reactions catalyzed by wild-type StEH1 (a, b) and R-C1 (c, d) for the (R,R)-enantiomer (a, c) and the (S,S)-enantiomer (b, d). The absolute energies for each reacting state are shown in black, and the relative energies for TS2 (relative to ISalk) are shown in red and blue for attack on C1 and C2, respectively. Finally, the experimentally observed regioselectivity for each system is shown at the bottom left of each plot (see Table 1[link]). The corresponding raw data are shown in Table 3[link] and bar charts of the activation free energies are shown in Fig. 8[link].

IUCrJ
Volume 5| Part 3| May 2018| Pages 269-282
ISSN: 2052-2525
https://doi.org/10.1107/S2052252518003573