• Bulletin of the Korean Chemical Society
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• 제27권11호
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• pp.1775-1779
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• 2006

A liquid chromatographic chiral stationary phase (CSP) based on (+)-(18-crown-6)-2,3,11,12-tetracarboxilic acid without extra free aminopropyl groups on silica surface has been demonstrated to be quite effective for the resolution of various $\beta$-amino acids. The retention factors ($k_1$) for the resolution of $\beta$-amino acids on the CSP were quite large and the large retention factors might be quite attractive along with the reasonable separation factors ($\alpha$) for preparative scale enantioselective chromatography. The large retention factors on the CSP were found to be reduced effectively by adding ammonium ion to mobile phase without sacrificing the chiral recognition efficiency of the CSP. Consequently, the CSP is also quite applicable for use in analytical enantioselective chromatography.

• Archives of Pharmacal Research
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• 제18권2호
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• pp.69-74
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• 1995

In order to improve physico-chemical properties and to enhance stability of drugs, amino acid salt has been widely adoptd in pharmaceutical synthesis. Acetylsalicylic acid lysinate is one of the widely used analgesics and it is a good example of t5his synthesis. In the case of bacetylsalicylic acid lysinate synthesis, racemization of natrually occurred lysine is esential because the racemic lysine salt of the drug shows better yield, crystallinity and dryness than that of the L-lysine salt. To esatablish a simple, practical and economical process for L-lysine racemization, L-lysine treatments with phosphoric acid and with acetic acid were compared and the optimum conditions for its process and derivatization were investigated by chiral separation methods using GC_MS spectroscopy.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1153-1163
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• 2005

Crown ether-based HPLC chiral stationary phases (CSPs) have been successfully utilized in the resolution of various racemic compounds containing a primary amino group. Especially, CSPs based on chiral crown ethers incorporating chiral binaphthyl unit or tartaric acid unit and based on phenolic pseudo chiral crown ethers have shown high chiral recognition efficiency. In this account paper, a review on the development of crown etherbased HPLC CSPs, their structural characteristics and applications to the resolution of racemic compounds including chiral drugs containing a primary or secondary amino group with the variation of the type and the content of mobile phase components and with the variation of the column temperature is presented.

• Bulletin of the Korean Chemical Society
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• 제33권5호
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• pp.1715-1718
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• 2012

2-Hydroxy-6-(1-(3-phenylurylphenyl)ethoxy)-benzaldehyde ($\mathbf{2}$) has been synthesized in racemic form from 1,3-Dihydroxybenzene via formylation and reaction with 3-phenyluryl-methylbenzylbromide. The optically pure form of $\mathbf{2}$ was separated by normal silica column chromatography from the imine diastreomer which was obtained by the reaction of racemic mixture of $\mathbf{2}$ with optically pure leucinol. The absolute configuration of the separated enantiomer of $\mathbf{2}$ was decided from the energy calculation of the corresponding imine diastereomers. The activity of $\mathbf{2}$ as a chirality conversion reagent (CCR) for amino acids was determined by $^1H$ NMR analysis. The efficiency of $\mathbf{2}$ is not better than the previous CCRs based on binaththol. Compound $\mathbf{2}$, however, has lower molecular weight compared to other CCRs. This work demonstrates that asymmetric carbon can control the selectivity of amino acids.

• Food Science and Biotechnology
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• 제17권6호
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• pp.1310-1315
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• 2008

This study was to investigate the influence of pH on the antioxidant activity of melanoidins formed from glucose (Glc) and fructose (Fru) with lysine enantiomers in the Maillard reaction. Melanoidins formed from D-isomers were found to be effective antioxidants in different in vitro assays with regard to the ferrous ion chelating activity, 1, l-diphenyl-2-picryl-hydrazil (DPPH) radical scavenging activities, ferric reducing/antioxidant power (FRAP), and 2,2'-azinobis(3-ethylbenothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging activity. In particular, the chelating activity of these melanoidins at a pH of 7.0 was greater than those with pH of 4.0 and 10.0. The chelating activity and DPPH radical scavenging activity of the melanoidins formed from the Glc systems were higher than those of the melanoidins formed from the Fru systems. However, the FRAP and ABTS radical scavenging activity of these melanoidins were not different according to pH level, with exceptions being the Fru systems.

• Journal of Microbiology and Biotechnology
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• 제25권12호
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• pp.2024-2033
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• 2015

A gene encoding lipolytic enzyme, lip7-3, was isolated from Bacillus sp. W130-35 isolated from a tidal mud flat. The gene encoded a protein of 215 amino acids with a signal peptide composed of 34 amino acid residues. Lip7-3 belonged to the family I.4 lipase and showed its maximal activity at pH 9.0 and 60℃. Its activity increased in the presence of 30% methanol and, remarkably, increased as well to 154.6% in the presence of Ca²⁺. Lip7-3 preferred p-nitrophenyl octanoate (C8) as a substrate and exhibited broad specificity for short- to long- chain fatty acid esters. Additionally, Lip7-3 showed a low degree of enantioselectivity for an S-enantiomer (e.g., (S)-methyl-3-hydroxy-2-methylpropionate). It efficiently hydrolyzed glyceryl tributyrate, but did not hydrolyze glyceryl trioleate, fish oil, or olive oil. Its substrate specificity and activation by the solvent might offer a merit to the biotechnological enzyme applications like transesterification in the production of biodiesel.

• Journal of Microbiology and Biotechnology
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• 제18권5호
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• pp.990-996
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• 2008

In a previous study, we found an antifungal effect on human pathogenic fungi by the cell-penetrating peptide Tat (47-58) derived from HIV-1. Tat (47-58) immediately entered into the fungal nucleus and affected some physiological changes on the intracellular condition. In this study, Tat (47-58) showed a broad spectrum of antibacterial activity against pathogenic bacteria including bacterial clinical isolates. To improve resistance against proteases for use in vivo, we synthesized an analog of Tat (47-58) by substituting the L-amino acid for the D-amino acid. The D-enantiomer of Tat (47-58) also exhibited a broad spectrum of antibacterial activity at almost the same level of L-Tat (47-58) concentration. Unlike L-Tat (47-58), D-Tat (47-58) showed a significant proteolytic resistance against all proteases tested and antimicrobial activities in the presence of trypsin. Moreover, D-Tat (47-58) inhibited MRSA infection in human HeLa cells whereas L-Tat (47-58) partially allowed MRSA infection, and the results were due to the proteolytic resistance of D-Tat (47-58).

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.625-628
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• 2001

토양으로부터 특이적인 광학 이성질체에 활성을 갖는 두 효소원을 선별한 후, 동정하여 Pseudomonas sp. S34와 B. stearothermophilus JY144로 명명하였고, genecloning과 sequencing을 통해 유전자의 특성 및 관련효소들과의 유연관계를 규명하였다. 규명된 정보의 분석과 비교를 통해 ketoprofen ethyl ester에 활성을 갖는 효소들의 구조적 특성을 추론할 수 있었고, 이를 바탕으로 발현시스템을 구축하였다. 대량생산된 효소를 활용한 반응의 결과 높은 수율과 순도를 갖는 각각의 광학이성질체를 경제적으로 생산할 수 있었다.