• Bulletin of the Korean Chemical Society
• /
• 제21권4호
• /
• pp.446-448
• /
• 2000

• Bulletin of the Korean Chemical Society
• /
• 제17권12호
• /
• pp.1096-1098
• /
• 1996

• Bulletin of the Korean Chemical Society
• /
• 제16권12호
• /
• pp.1138-1139
• /
• 1995

• Bulletin of the Korean Chemical Society
• /
• 제17권12호
• /
• pp.1178-1181
• /
• 1996

• Bulletin of the Korean Chemical Society
• /
• 제16권2호
• /
• pp.191-193
• /
• 1995

• Journal of Microbiology and Biotechnology
• /
• 제18권3호
• /
• pp.465-471
• /
• 2008

Highly active, stable, and magnetically separable immobilized enzymes were developed using carboxymethyl cellulose (CMC) and diethylaminoethyl cellulose DEAE-C; hereafter designated "DEAE" as supporting materials. Iron oxide nanoparticles penetrated the micropores of the supporting materials, rendering them magnetically separable. Lipase (LP) was immobilized on the surface of the supporting materials by using cross-linked enzyme aggregation (CLEA) by glutaraldehyde. The activity of enzyme aggregates coated on DEAE was approximately 2 times higher than that of enzyme aggregates coated on CMC. This is explained by the fact that enzyme aggregates with amine residues are more efficient than those with carboxyl residues. After a 96-h enantioselective ibuprofen esterification reaction, 6% ibuprofen propyl ester was produced from the racemic mixture of ibuprofen by using DEAE-LP, and 2.8% using CMC-LP.

• KSBB Journal
• /
• 제16권3호
• /
• pp.259-263
• /
• 2001

The development of hollow fiber reactor system for the production of chiral 1,2-epoxy-7-octence by epoxide hydrolase for Rhodotorula glutinis was investigated. Dodecane with high solubility of the racemic substrate passed through the lumen side of the hollow fiber reactor and cell suspension was recirculated through the shell side. The 2nd hollow fiber reactor was coupled to the production reactor to extract the diol byproduct which was the inhibitor of epoxide hydrolase. Optically pure (S)-1,2-epoxy-7-octene (0.6 M in dodecane) could be obtained using hollow-fiber reactor system.

• 한국생명과학회:학술대회논문집
• /
• 한국생명과학회 2001년도 제34회 학술심포지움
• /
• pp.21-28
• /
• 2001

A newly isolated Aspergillus niger possessing the novel epoxide hydrolase(EHase) activity was investigated for the enantioselective hydrolysis of racemic aromatic epoxides. The gene encoding EHase was cloned by RT-PCR, and molecular characteristics of the EHase gene were compared with other microbial EHases. The cloned gene encodes 398 amino acids with a deduced molecular mass of 44.5 kDa and pI of 4.83, and sequence homology with other microbial EHase was low. Functional recombinant EHase could be obtained by heterologous expressions in E. coli. Enantioselectivity of recombinant EHase was tested for valuable aromatic epoxide intermediates. Reaction conditions of EHase-catalyzed asymmetric resolution were optimized for the production of chiral styrene oxide.

• KSBB Journal
• /
• 제15권3호
• /
• pp.313-317
• /
• 2000

In this paper enantioselective production of levofloxacin by porcine liver esterase was investigated, To enhance the produc0-tivity various factors which affect the enzyme activity and the enantioselectivity were optimized, In terms of temperature and pH 45$^{\circ}C$ and 4.8 were found to be the best conditions for enzyme reaction. Addition of ofloxacin butyl ester the substrate at the concentration of 5 g/L was desirable to avoid the product inhibition and the activity of porcine liver esterase was maintained up to 72 hours.In addition to enhance the availability of substrate effect of solvent was also examined. It was found that the application of 5% (v/v) of acetone acetonitrile and dimethylsulfoxide did not increase the conversion of substrate and the presence of 5%(v/v) butanol inhibited the enzyme activity significantly.

• Bulletin of the Korean Chemical Society
• /
• 제28권12호
• /
• pp.2435-2441
• /
• 2007

The catalytic enantioselective electrophilic fluorinations of active methane compounds promoted chiral palladium complexes have been developed. Treatment of α-cyano acetates and α-cyanoalkylphosphonates with N-fluorobenzenesulfonimide as the fluorine source under mild reaction conditions afforded the corresponding α-cyano-α-fluorinated adducts in high yields with excellent enantiomeric excesses (up to 99% ee). These reactions can be conducted in alcoholic solvents without any precaution to exclude water and moisture.