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Ketoprofen Resolution by Enzymatic Esterification and Hydrolysis of the Ester Product
Wu, Jin Chuan,Low, Hou Ran,Leng, Yujun,Chow, Yvonne,Li, Ruijiang,Talukder, MMR,Choi, Won-Jae The Korean Society for Biotechnology and Bioengine 2006 Biotechnology and Bioprocess Engineering Vol.11 No.3
Immobilized Candida antarctica lipase was used to catalyze the separation of ketoprofen into its components by means of esterification followed by the enzymatic hydrolysis of the ester product. In this study, ketoprofen underwent esterification to ethanol in the presence of isooctane. When the reaction was complete, 58.3% of the ketoprofen had been transformed into an ester. The ketoprofen remaining in solution after the reaction was complete consisted primarily of its S-enantiomer (83.0%), while the 59.4% of the ketoprofen component of the ester consisted of its R-enantiomer. We then subjected the ester product to enzymatic hydrolysis in the presence of the same enzyme and produced a ketoprofen product rich in the R-enantiomer; 77% of this product consisted of the R-enantiomer when 50% of the ester had been hydrolyzed, and 90% of it consisted of the R-enantiomer when 30% of the ester had been hydrolyzed. By contrast, the R-enantiomer levels only reached approximately 42 and 65%, respectively, when 50 and 30% of the racemic ester was hydrolyzed under the same conditions.
Ketoprofen Resolution by Enzymatic Esterification and Hydrolysis of the Ester Product
Jin Chuan Wu,Hou Ran Low,Yujun Leng,Yvonne Chow,Ruijiang Li,MMR Talukder,Won Jae Choi 한국생물공학회 2006 Biotechnology and Bioprocess Engineering Vol.11 No.3
Immobilized Candida antarctica lipase was used to catalyze the separation of ketoprofen into its components by means of esterification followed by the enzymatic hydrolysis of the ester product. In this study, ketoprofen underwent esterification to ethanol in the presence of isooctane. When the reaction was complete, 58.3% of the ketoprofen had been transformed into an ester. The ketoprofen remaining in solution after the reaction was complete consisted primarily of its S-enantiomer (83.0%), while the 59.4% of the ketoprofen component of the ester consisted of its R-enantiomer. We then subjected the ester product to enzymatic hydrolysis in the presence of the same enzyme and produced a ketoprofen product rich in the R-enantiomer; 77% of this product consisted of the R-enantiomer when 50% of the ester had been hydrolyzed, and 90% of it consisted of the R-enantiomer when 30% of the ester had been hydrolyzed. By contrast, the R-enantiomer levels only reached approximately 42 and 65%, respectively, when 50 and 30% of the racemic ester was hydrolyzed under the same conditions.
Recovery of cellulases by adsorption/desorption using cation exchange resins
Jin Chuan Wu,Kiat Rui Ng,Joanne Chong,Kai Jie Yang,Xiao Ping Lam,Chai Teck Nam,Aninto Jati Nugroho 한국화학공학회 2010 Korean Journal of Chemical Engineering Vol.27 No.2
Cellulases from Trichoderma reesei were recovered by adsorption in sodium acetate buffer at lower pH using cation exchange resins followed by desorption at higher pH. The weakly acidic ion exchange resin WK10 was found to be the best among the six resins tested in terms of the enzyme activity recovery. The optimal pH values for the adsorption and desorption were 4.0 and 8.0, respectively, and the optimal adsorption and desorption times were both 5 h. Almost 100% of the initial cellulase activity was recovered under the optimal conditions with the supplement of β-glucosidase, which was unable to be efficiently recovered due to its strong adsorption (95.7%) but poor desorption (1.9%).
Jin Chuan Wu,Philip Ho,Tee Yuan Poh,Yvonne Chow,MMR Talukder,Won Jae Choi 한국화학공학회 2007 Korean Journal of Chemical Engineering Vol.24 No.4
immobilized Candida antarctica lipase, a commercially available and one of the most commonly usedenzymes, showed significantly improved enantioselectivity (twice) when used in a very acidic environment (pH 1.0)than in the normal pH 7.0 for the hydrolysis of ketoprofen ethyl ester at 45oC. The enzyme was still 60% active atpH 1.0 compared to the activity at pH 7.0 and its stabilities at the two pH values were almost the same. The improvedenantioselectivity was ascribed to the conformational change of the enzyme in the very acidic environment.
Physical properties and chemical composition of the cores in the California molecular cloud
Zhang, Guo-Yin,Xu, Jin-Long,Vasyunin, A. I.,Semenov, D. A.,Wang, Jun-Jie,Dib, Sami,Liu, Tie,Liu, Sheng-Yuan,Zhang, Chuan-Peng,Liu, Xiao-Lan,Wang, Ke,Li, Di,Wu, Zhong-Zu,Yuan, Jing-Hua,Li, Da-Lei,Gao, Springer-Verlag 2018 Astronomy and astrophysics Vol.620 No.-
<P><I>Aims.</I> We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation.</P><P><I>Methods.</I> We made a high-resolution column density map (18.2′′) with <I>Herschel</I> data, and extracted a complete sample of the cores in the CMC with the fellwalker algorithm. We performed new single-pointing observations of molecular lines near 90 GHz with the IRAM 30m telescope along the main filament of the CMC. In addition, we also performed a numerical modeling of chemical evolution for the cores under the physical conditions.</P><P><I>Results.</I> We extracted 300 cores, of which 33 are protostellar and 267 are starless cores. About 51% (137 of 267) of the starless cores are prestellar cores. Three cores have the potential to evolve into high-mass stars. The prestellar core mass function (CMF) can be well fit by a log-normal form. The high-mass end of the prestellar CMF shows a power-law form with an index <I>α</I> = −0.9 ± 0.1 that is shallower than that of the Galactic field stellar mass function. Combining the mass transformation efficiency (<I>ε</I>) from the prestellar core to the star of 15 ± 1% and the core formation efficiency (CFE) of 5.5%, we suggest an overall star formation efficiency of about 1% in the CMC. In the single-pointing observations with the IRAM 30m telescope, we find that 6 cores show blue-skewed profile, while 4 cores show red-skewed profile. [HCO<SUP>+</SUP>]/[HNC] and [HCO<SUP>+</SUP>]/[N2H<SUP>+</SUP>] in protostellar cores are higher than those in prestellar cores; this can be used as chemical clocks. The best-fit chemical age of the cores with line observations is ~5 × 10<SUP>4</SUP> yr.</P>