Enantioselective hydrolysis of styrene oxide with the epoxide hydrolase of Sphingomonas sp. HXN-200
2006; Elsevier BV; Volume: 17; Issue: 1 Linguagem: Inglês
10.1016/j.tetasy.2005.11.018
ISSN1362-511X
AutoresZeya Liu, Johannes Ehrenreich Josef Michel, Zunsheng Wang, Bernard Witholt, Zhi Li,
Tópico(s)Pharmacogenetics and Drug Metabolism
ResumoThe soluble bacterial epoxide hydrolase (EH) from Sphingomonas sp. HXN-200 catalyzed the enantioselective hydrolysis of racemic styrene oxide to give (S)-styrene oxide with an enantiomeric ratio (E) of 21–23 in aqueous buffer, better than any reported native EHs. The ring opening of the styrene oxide with this EH was only at the terminal position for the (S)-enantiomer and at the terminal and benzylic position in an 87:13 ratio for the (R)-enantiomer. Enzymatic hydrolysis of the styrene oxide in a two-liquid phase system significantly reduced autohydrolysis, thus improving the E to 26–29. Hydrolysis of 160 mM styrene oxide with cell-free extract (CFE) of Sphingomonas sp. HXN-200 (10 mg protein/mL) in aqueous buffer and n-hexane (1:1) for 30.7 h afforded 39.2% (62.7 mM) of (S)-styrene oxide in >99.9% ee. The lyophilized CFE was proven to be stable, while the rehydrated lyophilized CFE powder was successfully used for the hydrolysis of 320 mM styrene oxide in the two-liquid phase system, yielding 40.2% (128.6 mM) of (S)-styrene oxide in >99.9% ee after 13.8 h. No inhibitory effect of the diol product on the hydrolysis was observed when the diol concentration was lower than 476 mM, suggesting a straightforward process for the hydrolysis of up to 1 M styrene oxide.
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