• Korean Chemical Engineering Research
• /
• v.54 no.1
• /
• pp.81-88
• /
• 2016

Limonene is orange flavored natural material that is mainly contained in mandarine and lemon peels. D-limonene was extracted from cold-storaged mandarine peel by using Soxhlet extractor at $120^{\circ}C$ for 2 hours with ethanol as solvent. Henry constants of d-limonene and impurity were calculated as $H_{Lim}=8.55$ and $H_{imp}=0.223$ from the result of HPLC analysis. 4-bed SMB of limonene simulation with $0.46{\times}25cm$ columns was conducted by using Aspen chromatography program. Then effective condition for purity was found by changing $m_2$ and $m_3$ values in triangle diagram. The highest purity was 98.59% at $m_2=2.57$, $m_3=9.55$. For this case, feed, desorbent, extract, and raffinate flow rates were 1 mL/min, 1.19 mL/min, 0.857 mL/min and 1.34 mL/min, respectively. Scale-up simulation was also conducted by increasing column diameter from 0.46 cm to 1.6 cm for getting the same efficiency. The increased flow rates were 12 mL/min, 14 mL/min, 10 mL/min, and 16 mL/min for feed, desorbent, extract, and raffinate. It was possible to scale-up with maintaining same limonene purity because linear isotherms of limonene and impurity were assumed.

• Microbiology and Biotechnology Letters
• /
• v.37 no.2
• /
• pp.118-124
• /
• 2009

Esterase EM2L8 gene isolated from deep sea sediment was expressed in Escherichia coli BL21 (DE3) and the esterase activity of the cell-free extract was assayed using p-nitrophenyl butyrate-spectrophotometric method. Its optimum temperature was $40-45^{\circ}C$ and 45% activity of the maximum activity was retained at $15^{\circ}C$. The activation energy at $15-45^{\circ}C$ was calculated to be 4.9 kcal/mol showing that esterase EM2L8 was a typical cold-adapted enzyme. Enzyme activity was maintained for 6 h and 4 weeks at $30^{\circ}C$ and $4^{\circ}C$, respectively. When each ethanol, methanol, and acetone was added to the reaction mixture to 15% concentration, enzyme activity was maintained. In the case of DMSO, enzyme activity was kept up to 40% concentration. (S)-4-Chloro-3-hydroxy butyric acid is a chiral intermediate for the synthesis of Atorvastatin, a hyperlipemia drug. When esterase EM2L8 (40 U) was added to buffer solution (1.2 mL, pH 9.0) containing ethyl-(R,S)-4-chloro-3-hydroxybutyrate (38 mM), it was hydrolyzed into 4-chloro-3-hydroxy butyric acid with a rate of $6.8\;{\mu}mole/h$. The enzyme hydrolyzed (S)-substrate more rapidly than (R)-substrate. When conversion yield was 80%, e.e.s value was 40%. When DMSO was added, hydrolysis rate increased to $10.4\;{\mu}mole/h$. The plots of conversion yield vs e.e.s in the presence or absence of DMSO were almost same, implying that the reaction enantioselectivity was not changed by the addition of DMSO. Taken together, esterase EM2L8 had high activity and stability at low temperatures as well as in various organic solvents/aqueous solutions. These properties suggested that it could be used as a biocatalyst in the synthesis of useful pharmaceuticals.