• Biotechnology and Bioprocess Engineering:BBE
• /
• 제6권2호
• /
• pp.150-155
• /
• 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.

• 한국미생물·생명공학회지
• /
• 제24권2호
• /
• pp.222-226
• /
• 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.

• 한국응용과학기술학회지
• /
• 제9권1호
• /
• pp.7-13
• /
• 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
• /
• 제9권1호
• /
• pp.63-71
• /
• 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
• /
• 제11권2호
• /
• pp.205-213
• /
• 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

• 한국식품영양과학회지
• /
• 제23권3호
• /
• pp.496-501
• /
• 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
• /
• 제11권5호
• /
• pp.884-886
• /
• 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
• /
• 제6권3호
• /
• pp.281-288
• /
• 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.

• 대한화학회지
• /
• 제38권6호
• /
• pp.449-455
• /
• 1994

효소를 이용한 생리활성 펩티드의 합성 연구에 관한 기초자료를 얻기 위하여, Kyotorphin(진통작용을 가진 펩티드) 유도체가 $\alpha-chymotrysin$를 이용한 이상계(two phase system;유기상과 수용액상)조건하에서 Ac-Tyr-OH 와 $Arg-NH_2$로부터 합성되었다. Ac-Tyr-OH(10 mM)과 $Arg-NH_2$ (20 mM)와의 Kyotorphin 유도체 합성에 대한 유기용매의 효과에서 ethyl acetate계에서의 합성 수율이 다른 유기용매(dichloromethane, n-butanol, n-hexane, chloroform)에서 보다도 더 높았다. Kyotorphin 유도체의 합성에 미치는 최적조건을 보면, 효소 농도는 10 ${\mu}M$, 온도 및 pH는 각각 $35^{\circ}C$ 및 7.0이었으며, 유기상/수용액상의 비$(\alpha)$는 15였다. Kyotorphin 유도체 합성의 최적 반응조건하에서 수율은 70.2%였으며, 이때의 반응은 24시간 후에 평형에 도달하였다.

• 한국균학회지
• /
• 제15권1호
• /
• pp.23-28
• /
• 1987

R. nigricans Ehrenberg 에 의한 progesterone 의 $11{\alpha}-hydroxyprogesterone$에 영향을 미치는 여러 물러 화학적 요인에 대하여 조사하였다. Progesterone의 농도가 낮을수록 $11{\alpha}-hydroxyprogesterone$이 최고의 수득율에 도달하는데 소요되는 시간이 짧았으며, 높은 기질 농도에서의 Progesterone은 $11{\alpha}-hydroxyprogesterone$의 hydroxylation을 저해하였다. 이 반응에 대한 최적 pH와 온도 범위는 비교적 넓은 범위로 나타났으며, 균사제의 성장 죄적 조건과 유사하였다. 일정 속도 이상의 진탕 속도와 당류들은 $11{\alpha}-hydroxyprogesterone$ 반응을 촉진시키는 효과를 보였으매, 균사체에서 보다 포자를 효소원으로 사용하였을 때 glucose의 효과는 더 크게 나타났다. 유기 용매는 효소 활성 저해제로 작용하었으며, 저해 정도는 유기 통매 농도가 높을수록, 용매에 처리한 시간이 길어질수록 높게 나타났다.