• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.2
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• pp.150-155
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• 2001

It has been observed that water, which is absolutely essential for enzyme activity, can induce the agglomeration of enzyme particles in organic media. Although enzyme agglomeration is significant in that it usually reduces enzyme activity and stability, little attention has been paid to the quantitative analysis of enzyme agglomeration behavior in nonaqueous biocatalytic systems. In this study, the effect of water and silica gel on enzyme agglomeration were investigated using Candida rugosa lipase and cyclohexane as a model enzyme and an organic medium. The extent of enzyme agglomeration was quantified by sieve analysis of freeze-dried agglomerates. Increasing the water content of the medium increased the size of the enzyme agglomerates, and it was found that water produced during the esterification reaction could also promote the agglomeration of enzyme particles suspended in organic media. On the other hand, the size of the enzyme agglomerates was remarkably reduced in the presence of silica gel at the same water content. We also show that this increase in the size of enzyme agglomerates results in lower reaction rates in organic solvents.

• Microbiology and Biotechnology Letters
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• v.24 no.2
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• pp.222-226
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• 1996

The enzymatic synthesis of 3, 4-dihydroxyphenyl-L-alanine (L-DOPA) was examined for the effects of the reaction additives such as sodium borate, alcohol, and organic solvents. The enzyme used was tyrosine phenol-lyase of Citrobacter freundii KCTC 2006 produced in Escherichia coli. The amounts of tyrosine phenol-lyase and pyridoxal-5-phosphate were optimized to 2.0 units/ml and 0.1 mM, respectively, for the synthetic reaction. Sodium borate, a substance that forms a complex with pyrocatechol, reduced the enzyme deactivation by pyrocatechol although it seriously inhibited the enzyme activity. Among the organic solvents tested, dimethylsulfoxide, dimethylformamide, and alcohol increased the productivity of the L-DOPA synthesis. In a reaction system with 5% methanol, L-DOPA concentration increased up to 210 mM after 24 hours, and 77.1% of which was separated as precipitates. The L-DOPA was purified to 99.96% by solubilizing and recrystallyzing the precipitates.

• Journal of the Korean Applied Science and Technology
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• v.9 no.1
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• pp.7-13
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• 1992

Lipases catalyzed the transesterification reaction between esters and various primary and secondary alcohols in a 99% organic medium, porcine pancreatic, yeast, mold lipases can vigorously act as catalysts in a number of nearly anhydrous organic solvents. Various transesterification reactions catalyzed by porcine pancreatic lipase in hexane obey Michaelis-Menten kinetics. The dependence of the catalytic activity of the enzyme in organic media on the pH of the aqueous solution from which it was recovered is bell-shaped, with the maximum coinciding with the pH optimum of the enzymatic activity in water. The catalytic power exhibited by the lipases in organic solvents is comparable to that displayed in water. In addition to transesterification, lipases Can catalyze several other processes in organic media.

• KSBB Journal
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• v.9 no.1
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• pp.63-71
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• 1994

During the last decade enzyme reaction in organic solvent has been studied to show that specificity in buffer is different from that in organic solvent. The specificity of restriction enzyme was effected by various factors such as ionic strength, salt organic solvent and temperature. In this study, restriction enzyme PvuII which is used most frequently in genetic engineering and the substrate was vector pGEM3 whose sequence was already known were used. As a result the recognition sequence site was changed in the presence of organic solvents whose Log P are -1.5∼0. Their specificities were contrast with activities were contrasted. Specificities were not changed in organic solvent easily in inactivating enzyme. We think that the enzyme recognition site was not changed randomly but by preferential order. A recombinant vector which does not contain typical cleavage site CAG↓CTG was cleaved in 20% ethanol solution. This result might show that restriction enzyme could be used to cleave at unusual sites by changing the reaction conditions.

• Toxicological Research
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• v.11 no.2
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• pp.205-213
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• 1995

This study was undertaken to investigate the effects of organic solvents on xenobiotic metabollzing enzyme system in vivo by meaas of experimental conditions i.e. (1) single group which was treated by benzene (B), toluene (T) and xylene (X), respectively, (2) combination group which was treated by mixture of benzene+toluene (BT), benzene+xylene (BX), and toluene+xylene (TX), respectively, (3) mixture group which was treated by benzene+ toluene+xylene mixture (M), and to interpreat the interaction between the organic solvents metabolizing enzymes. 1. The contents of cytochrome P-450 in liver microsomes were increased (p < 0.01) in organic solvents treated groups, and the contents of cytochrome P-450 were increased by following order of B < T < M < BT=BX < X < TX. 2. The activity of cytochrome P-450 dependent AHHase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the activity of AHHase was increased by following order of B < T < BT=BX=TX=xylene < M. 3. The activity of NADPH P-450 reductase was significantly higher in organic solvents treated groups than in control group (p < 0.01), and the order of M < combinated group < X < T

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.3
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• pp.496-501
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• 1994

The synthesis of lauryl palmitate from palmitic acid and lauryl alcohol was investigated in organic solvents using lipase. Water-immiscible organic solvent such as hexane, toluenem cyclohexane, and isooctane were found to be suitable of ester synthesis . The effect of water content on the initial rate of conversion was examined . As the content increased, the reaction rate increased. But addition of water in organic solvent decreased therostability of enzyme . The best lauryl palmitate synthesis was achieved with water content of 0.2-0.4% reaction temperature of 4$0^{\circ}C$ and 45$^{\circ}C$ for Candida cylindracea lipase porcine, pancreatic lipase, respectively. when ester synthesis was carried out under the optimum conditions, the conversion yield of palmitate into lauryl palmitate after 70hrs reached 85% and 69 % for the Candida cylindracea lipase and porcine opancreatic lipase, respectivley.

• Journal of Microbiology and Biotechnology
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• v.11 no.5
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• pp.884-886
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• 2001

The reactivity and stability of purified Lignostilbene- ${\alpha}$,${\beta$}-dioxygenase (LSD)-I were examined. Its optimum temperature was $50^{\circ}C$ at pH 8.5, but it was stable only up to $30^{\circ}C$. The activity of LSD-I increased 12-fold by $30\%$, with increased $V_{max}$ and lowered $K_m.$ LSD-I was stable in 10% methanol.

• KSBB Journal
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• v.6 no.3
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• pp.281-288
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• 1991

This research was carried to investigate the effects of several organic solvents on the enzymatic transphosphatidylation in emulsion and two-phase solvent systems. The solvents having a similar dielectric constant with diethylether were effective for the enzyme activity. Diethylether and butylacetate were the most effective solvents, when added 12-15%(v/v) and 10-40%(v/v), respectively, for the synthesis of phosphatidylglycerol, phosphatidylethyleneglycol and phosphatidylpropyleneglycol. In the emulsion system, the size of ovolecithin liposome was increased and the clearness of the phospholipid bilayer was reduced as increasing the diethylether concentration. In the twophase solvent system, the rapidest reaction was obtained when water-organic solvent ratio was close to 1. The ratio of aqueous phase. however, should be lowered to 37% to gain the sole product of transphosphatidy1ation, without phosphatidohydrolysis.

• Journal of the Korean Chemical Society
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• v.38 no.6
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• pp.449-455
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• 1994

In order to obtain the basic data for synthetic studies of bioactive peptide using enzyme, Kyotorphin(analgesic peptide) derivative was synthesized from Ac-Tyr-OH and $Arg-NH_2$ by $\alpha-chymotrysin$ in two phase system(organic phase and aqueous phase). In effect of organic solvent on Kyotorphin derivative synthesis from Ac-Tyr-OH(10 mM) and $Arg-NH_2$ (20 mM), the synthesis in ethyl acetate system of organic solvents was higher than those in other organic solvents (n-butanol, n-hexane, dichloromethane and chloroform). The optimal conditions for the synthesis are as follows: enzyme conc., 10 ${\mu}M;$ reaction pH, 7.0; reaction temp., $35^{\circ}C$ ; the ratio of organic phase volume/aqueous phase volume $(\alpha)$, 15. Under the optimal conditions, the yield was 70.2%, and the reaction achieved to equilibrium after 24 hrs.

• The Korean Journal of Mycology
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• v.15 no.1
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• pp.23-28
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• 1987

Physicochemical factors influencing the $11{\alpha}$, hydroxylation of progesterone by Rhizopus nigricans Ehrenberg were studied. The higher is the concentration of progesterone. the shorter time is need to attain maximum yield in the $11{\alpha}-hydroxyprogesterone$. High concentration in progesterone was supposed to inhibit the hydroxylation reaction of the $11{\alpha}-hydroxyprogesterone$. The range of optimum pH and temperature appeared to be rather broad and these conditions were similar to those of optimum growth of the mycelia. Agitation at a higher speed than a certain limit, and the presence of sugars accelerated the $11{\alpha}-hydroxyprogesterone$ reaction. Glucose was found to be more effective for the reaction using spores rather than mycelia as enzyme sources. Organic solvents were proved to supress the enzyme activity, which decreased with increase in the concentration of the organic solvents and in the time for pretreatment with the solvents.