Epoxide hydrolase activity of Streptomyces strains.
The discovery of epoxide hydrolases within a Streptomyces sp. strain collection is described. Screening was performed in 96 well microtiter plates using a modified 4-(p-nitrobenzyl)pyridine assay with styrene oxide, 1,2-epoxy-hexane or 3-phenyl ethylglycidate (3-PEG) as substrates. Out of 120 strains investigated, S. antibioticus Tü4, S. arenae Tü495 and S. fradiae Tü27 exhibited epoxide hydrolase activity. These strains were further investigated by performing laboratory-scale biotransformations utilizing styrene oxide, 1,2-epoxy-hexane and 3-PEG followed by subsequent quantitative analysis employing chiral gas chromatography. The highest conversions were achieved with whole cells from S. antibioticus Tü4 in the presence of 10% (v/v) DMSO. However, enantioselectivity was only satisfying (E = 31) in the presence of 5% (v/v) acetone, which allowed isolation of optically pure non-hydrolyzed (R)-styrene oxide (99% enantiomeric excess (ee)) and (S)-phenyl-1,2-ethandiol (72% ee) at 55% conversion after 24 h. The resolution of 3-PEG proceeded with slightly lower enantioselectivity albeit higher reaction rates. With S. fradiae Tü27 and S. arenae Tü495 enantioselectivity towards styrene oxide was only E = 3-4.
Zocher
F
F
Institut für Technische Biochemie, Universität Stuttgart, Germany.
Enzelberger
M M
MM
Bornscheuer
U T
UT
Hauer
B
B
Wohlleben
W
W
Schmid
R D
RD
D004851:Epoxide Hydrolases / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism; D013302:Streptomyces / Q000201:enzymology*
D004852:Epoxy Compounds; C013690:styrene oxide; D004851:Epoxide Hydrolases