Improved catalytic performance of Bacillus megaterium epoxide hydrolase in a medium containing Tween-80.
A new epoxide hydrolase with high enantioselectivity toward (R)-glycidyl phenyl ether (R-GPE) was partially purified from Bacillus megaterium strain ECU1001. The maximum activity of the isolated enzyme was observed at 30 degrees C and pH 6.5 in a buffer system with 5% (v/v) of DMSO as a cosolvent. The enzyme was quite stable at pH 7.5 and retained full activity after incubation at 40 degrees C for 6 h. Interestingly, when the cosolvent DMSO was replaced by an emulsifier (Tween-80, 0.5% w/v) as an alternative additive to help disperse the water-insoluble substrate, the apparent activity of the epoxide hydrolase significantly increased by about 1.8-fold, while the temperature optimum shifted from 30 to 40 degrees C and the half-life of the enzyme at 50 degrees C increased by 2.5 times. The enzymatic hydrolysis of rac-GPE was highly enantioselective, with an E-value (enantiomeric ratio) of 69.3 in the Tween-80 emulsion system, which is obviously higher than that (41.2) observed in the DMSO-containing system.
Gong
Peng-Fei
PF
Laboratory of Biocatalysis and Bioprocessing, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, P. R. China.
Xu
Jian-He
JH
Tang
Yan-Fa
YF
Wu
Hui-Yuan
HY
D001410:Bacillus megaterium / Q000737:chemistry / Q000201:enzymology*; D002384:Catalysis; D003067:Coenzymes / Q000737:chemistry* / Q000378:metabolism; D004121:Dimethyl Sulfoxide / Q000737:chemistry* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D020536:Enzyme Activators / Q000737:chemistry; D004795:Enzyme Stability / Q000187:drug effects; D004851:Epoxide Hydrolases / Q000096:biosynthesis* / Q000737:chemistry*; D007536:Isomerism; D011136:Polysorbates / Q000737:chemistry* / Q000494:pharmacology; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature
D003067:Coenzymes; D020536:Enzyme Activators; D011136:Polysorbates; D012996:Solutions; D012997:Solvents; D004851:Epoxide Hydrolases; D004121:Dimethyl Sulfoxide