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许建和, P.-F. Gong
Appl Microbiol Biotechnol (2002) 58: 728~734,-0001,():
-1年11月30日
The yeast strain CGMCC 0573 was identified as Citeromyces matriensis and shown to be capable of enantioselectively hydrolyzing ethyl ester of (R)-Ketoprofen (2-(3-benzoylphenyl)propionic acid). The strain was isolated for the first time from soil samples through a new and efficient screening procedure in which the probability of obtaining active strains was greatly increased by using ethanol and Tween-80 alternatively as additives during the enrichment culture. Studies of the culture conditions and catalytic performance of Citeromyces matriensis CGMCC 0573 showed that the enzyme occurs constitutively in the cells and its production is enhanced by feeding with Tween-80 during the early period of cultivation. Yeast extract was found to be beneficial both for growth and for esterase production. The optimal temperature and pH for the bioconversion were 40℃ and pH 8.0, respectively. Biotransformation using resting cells cultured in a flask with baffles and magnetic stirring and in the presence of 50mM substrate resulted in the production of (R)-ketoprofen at 93% ee (enantiomeric excess) and at 42.6% conversion.
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许建和, Li Gao
Ind Microbiol Biotechnol (2004) 31: 525~530,-0001,():
-1年11月30日
Lipase production and cell growth of Serratia marcescens ECU1010 were optimized in shake flasks, with lipase production being enhanced 9.5-fold (4,780 U/l) compared with the initial activity (500 U/l). Optimal carbon and nitrogen sources were Tween-80 and peptone, and the optimal ratio of Tween-80 to peptone was 1:3. The optimized cultivation conditions were 25[1]C and pH 6.5. Lipase activity, particularly specific activity, could be improved by decreasing the cultivation temperature from 35 to 25[1]C. Enzyme stability was significantly improved by simple immobilization with synthetic adsorption resin no. 8244. After five reaction cycles, enzyme activity decreased only very slightly, while enantioselectivity of the preparation remained constant, and the ees (enantiomeric excess of the remaining substrate) achieved in all cases was higher than 97%. The resin-8244-lipase preparation can be used for efficient enantioselective hydrolysis of trans-3-(4
Serratia marcescens ECU1010
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【期刊论文】Asymmetric reduction of aryl ketones with a new isolate Rhodotorula sp. AS2.2241
许建和, Ye Ni, Jian-He Xu*
Journal of Molecular Catalysis B: Enzymatic 18(2002)233~241,-0001,():
-1年11月30日
A yeast strain, Rhodotorula sp. AS2.2241, capable of reducing acetophenone and -bromoacetophenone with high stereoselectivity, was isolated from soil samples through a novel screening procedure in which acetophenone was supplied in vapor state as the sole carbon and energy source. The biosynthesis of the ketone reductase in the yeast cells reached a maximum of 41.0 U/l at 20h of cultivation. The reductase isolated from the Rhodotorula sp. cells was partially purified by 52.6-fold through a single column chromatography of DEAE-cellulose. The catalytic performance of the partially purified reductase was examined, and the highest activitywas observed at pH 6.5 and 50 ◦C. The short-chain alkyl aldehydes such as acetaldehyde and those aldehydes or ketones with a benzoyl group were found to be good substrates for the reductase. In the preparative bioreductions of 50mM acetophenone and 2mM -bromoacetophenone using resting cells of Rhodotorula sp. AS2.2241, (S)-(−)-1-phenylethanol (>99.5% enantiomeric excess (e.e.), 34.7% yield) and (R)-(−)-2-bromo-1-phenylethanol (>99.9% e.e., 19.9% yield) were obtained, respectively.
Acetophenone, a-Bromoacetophenone, Asymmetric reduction, Ketone reductase, Aldehyde reductase, Rhodotorula sp.,
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【期刊论文】Significant enhancement of lipase enantioselectivity toward (S)-Ketoprofen ester at pH 2
许建和, You-Yan Liu, Jian-He Xu, Qiu-Ge Xu & YingHu
Biotechnology Letters 21: 143~146, 1999.,-0001,():
-1年11月30日
The optimal activity of a Candida rugosa lipase (Lipase OF) for hydrolysis of 2-chloroethyl ester of Ketoprofen [2-(3-benzoyphenyl) propionic acid] was at pH 4.0, while the best enantioselectivity (E) was at pH 2.2 where the enzyme was still 60% active and stable.
(, S), -Ketoprofen,, Candida rugosa lipase,, pH effect,, activity,, enantioselectivity
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许建和, You-Yan Liu, Jian-He Xu*, Ying Hu
Journal of Molecular Catalysis B: Enzymatic 10(2000)523~529,-0001,():
-1年11月30日
An additive method has been developed to obtain nearly optically pure (S)-ketoprofen wS.-2-(3-benzoyphenyl)propionicacid, >96% enantiomeric excess, eex by using lipase OFfrom Candida rugosa.for the first time. The effect of surfactantsselected as additives.on the enantioselective hydrolysis of 2-chloroethyl ester of ketoprofen by the crude and the purified C. rugosa lipase (lipase OF) was investigated. Except for Tween-60, Tween-80 and nonyl phenol polyethyleneoxy etherOP-10., most of the other surfactants tested had inhibitory influence on the lipase. As for the enantioselectivity, only Tween-80 displayed a positive effect. Moreover, the concentration of Tween-80 was found to be a sensitive factor affecting the activity and the enantioselectivity, when either the crude or the purified enzyme was used. Upon addition of the two emulsifiers at their optimal concentrations, i.e., 2%(w/v) Tween-80 and 3%(w/v) OP-10, the crude enzyme activity was greatly enhanced up to 13 and 15 times, respectively. On the other hand, the enantiomeric ratio (E value) increased from 1.2 to 6.7 for the crude lipase and from 8 to>100 for the purified lipase in the presence of 8% or 2%(w/v) Tween-80.
Candida rugosa lipase, Enantioselectivity, Activity, Ketoprofen, Tween-80
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