• KSBB Journal
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• v.19 no.5
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• pp.385-389
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• 2004

In this research, the chemo-enzymatic synthesis of sorbitan methacrylate was investigated to optimize reaction conditions. Firstly, sorbitan was manufactured by sorbitol cyclic reaction in the presence of p-toluenesulfonic acid (p-TSA) as catalyst material. Secondly, sorbitan methacrylate was synthesized by immobilized lipase Novozyme 435 with acyl donors in t-butanol. As a result of enzymatic synthesis of sorbitan methacrylate, the conversion yield reached about $65\%$ in the condition of initial sorbitan conc. 50 g/L, enzyme content $3\%$ (w/v) , molar ratio 1:3, reaction temperature 50^{circ}C and reaction time 42 hrs using methyl methacrylate as acyl donor. Comparing with acyl donors and reaction temperature, the conversion yield reached about 18, 65 and $80\%$ with methacrylic acid, methyl methacrylate and vinyl methacrylate as acyl donor, respectively. And optimum reaction temperature was 60, 50, and 50^{circ}C, respectively

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.621-621
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• 2003

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2065-2071
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• 2014

${\beta}$-Secretase (beta-amyloid converting enzyme 1 [BACE1]) is involved in the first and rate-limiting step of ${\beta}$-amyloid ($A{\beta}$) peptides production, which leads to the pathogenesis of Alzheimer's disease(AD). Therefore, inhibition of BACE1 activity has become an efficient approach for the treatment of AD. Ligand-based and docking-based 3D-quantitative structure-activity relationship (3D-QSAR) studies of acyl guanidine analogues were performed with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) to obtain insights for designing novel potent BACE1 inhibitors. We obtained highly reliable and predictive CoMSIA models with a cross-validated $q^2$ value of 0.725 and a predictive coefficient $r{^2}_{pred}$ value of 0.956. CoMSIA contour maps showed the structural requirements for potent activity. 3D-QSAR analysis suggested that an acyl guanidine and an amide group in the $R_6$ substituent would be important moieties for potent activity. Moreover, the introduction of small hydrophobic groups in the phenyl ring and hydrogen bond donor groups in 3,5-dichlorophenyl ring could increase biological activity.

• Bulletin of the Korean Chemical Society
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• v.25 no.10
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• pp.1471-1473
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• 2004

An efficient dynamic kinetic resolution of racemic ${\beta}$-hydroxyalkylferrocene and 1,1'-bis( ${\beta}$-hydroxyalkyl)-ferrocene derivatives was achieved using lipase/ruthenium-catalyzed transesterification in the presence of an acyl donor. The racemic ${\beta}$-hydroxyalkylferrocene derivatives were successfully transformed to the corresponding chiral acetates of high optical purities in high yields.

• Applied Chemistry for Engineering
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• v.17 no.6
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• pp.658-664
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• 2006

$\rho$, $\alpha$-dimethyl benzyl alcohol was resolved by the biphasic dynamic kinetic resolution (DKR). Acidic zeolite was used as a racemization catalyst while immobilized enzyme was employed for kinetic resolution. The effects of the process variables including nature of acyl donor, reaction temperature, substrate concentration, ratio of the two catalysts and stirring rate on the conversion and enantiomeric purity of the product were investigated. In DKR of $\rho$, $\alpha$-dimethyl benzyl alcohol, the product of 99% ee was obtained with a maximum yield of 88%. The high performance of the catalyst system was maintained in the condition of higher TON and under repeated use.

• Korean Journal of Microbiology
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• v.33 no.3
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• pp.181-186
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• 1997

Sugar ester compounds were synthesized in organic solvent using lipase. Anhydrous pyridinc was selected as ;I solvent because of reasonable solubility of sugar. The synthesis of sugar ester compound was catalyzed by Pseudomonas sp. lipase in the reaction system containing anhydrous pyridine as .i solvent and vinyl butylate as an acyl donor. The analysis of the reaction product by TLC and GC showed thilt monobutyryl and dibutyryl fructose esters were synthesized by transesterification reaction between fructose and vinyl butyrate. Optimal conditions for the transesterification reaction were as follows: the ratio of fructoselvinyl butylate, I : lO(M : M): reaction temperature, 40^{\circ}C.$, velocity of shaking, 150 rprn: concentration of enzyme, 10 mglml. The longer the reaction period, the higher the conversion rate, and the conversion rate reached up to 90% after about 10 days of reaction. Monobutyryl fructose was mainly synthesized in the early stage of reaction, but the amount of dibutyryl fructose increased gradually as the rcdction progressed. When a small amount of water was added to the reaction mixture (micro-water system), the reaction rate decreased, while that of rnonobutyr~l fructosc increased. Only monobutyryl fructose was obtained when 1% water was added to the reaction mixture.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.296-299
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• 2005

Sugar polymers have been considered as biomaterial. Biomaterials are widely utilized for a medical applications in direct contact with living tissue Clearly, biomaterials must be carefully and microscopically fabricated for optimal acceptance within the living organism in both functional and structural senses. In this study, the enzymatic synthesis of sorbitan methacrylate from 1,4-sorbitan via the manipulation of an immobilized biocatalyst (Novozym 435) and acryl donors (methacrylic acid and vinyl methacrylate) was evaluated.

• KSBB Journal
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• v.9 no.3
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• pp.306-311
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• 1994

Optical resolution of racemic ${\alpha}$-methylbenzylamine was carried out by using Bacillus licheniformis protease in organic media. Enantioselective amidation of racemic amino with an ester as an acyl donor was successfully employed to resolve the racemate. To enhance reaction rate and enantioselectivity, pH-adjustment by lyophilization of enzyme dissolved in buffer, colyophilization with salts or lyoprotectants, selection of solvents and molecular design of esters were investigated. The optimization of the resolution reaction achieved about 30-fold increase in initial reaction rate and about 12-fold increase in enantioselectivity, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.1
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• pp.99-102
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• 2005

Organic solvents are widely used in biotransformation systems. There are many efforts to reduce the consumption of organic solvents because of their toxicity to the environment and human health. In recent years, several groups have started to explore novel organic solvents called room temperature ionic liquids in order to substitute conventional organic solvents. In this work, lipase-catalyzed transesterification in several uni- and bi-phasic systems was studied. Two representative hydrophobic ionic liquids based on 1-butyl-3-methylimidazolum coupled with hexafluorophosphate ([BMIM][$PF_6$]) and bis[{trifluoromethylsulfonyl} imide] ([BMIM] [$Tf_{2}N$]) were employed as reaction media for the transesterification of n-butanol. The commercial lipase, Novozym 435, was used for the transesterification reaction with vinyl acetate as an acyl donor. The conversion yield was increased around $10\%$ in a water/[BMIM][$Tf_{2}N$] bi-phasic system compared with that in a water/hexane system. A higher distribution of substrates into the water phase is believed to enhance the conversion yield in a water/[BMIM][$Tf_{2}N$] system. Partition coefficients of the substrates in the water/[BMIM][$Tf_{2}N$] bi-phasic system were higher than three times that found in the water/hexane system, while n-butyl acetate showed a similar distribution in both systems. Thus, RTILs appear to be a promising substitute of organic solvents in some biotransformation systems.

• Journal of Life Science
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• v.20 no.1
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• pp.97-102
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• 2010

Streptomyces platensis YK-2, newly isolated from forest soil, produces transglutaminase (TGase), which catalyses an acyl transfer reaction between the primary grade amine and protein or $\gamma$-carboxyamide group of peptide bound glutamine residues. For a molecular genetic study of S. platensis, an effective transformation method was established by using a conjugal transfer of DNA from Escherichia coli to spores of actinomycetes. The highest transconjugation frequency of S. platensis was obtained on an MS medium containing 50 mM $MgCl_2$, using $5{\times}10^7\;E$. coli as a DNA donor and $1{\times}10^8$ spores without heat treatment as a host. We also identified that S. platensis contains a single attB site within an ORF encoding a pirin-homolog, and that its attB site sequence shows high homology to that of S. logisporoflavus. In addition, it was confirmed by phenotypic analyses of exconjugants that the introduction of heterologous DNA into the attB site of the S. platensis chromosome does not affect its morphological differentiation and TGase production.