• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1105-1109
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• 1998

A chiral stationary phase derived from (S)-N-(3,5-dinitrobenzoyl)leucine N-phenyl N-alkyl amide (CSP 2) was applied in separating the two enantiomers of various π-basic aromatic derivatives of leucine N-propyl amide in order to evaluate π-basic aromatic groups as an effective derivatizing group for the resolution of a-amino acids. Subsequently N-(3,5-dimethoxybenzoyl) group was found to be very effective as a π-basic aromatic derivatizing group. Based on these results, N-(3,5-dimethoxybenzoyl) derivatives of various a-amino N-propyl amides, N,N-diethyl amides and esters were resolved on the CSP derived from (S)-N-(3,5-dinitrobenzoyl) leucine N-phenyl N-alkyl amide (CSP 2) and the resolution results were compared with those on the CSP derived from (S)-N-(3,5-dinitrobenzoyl)leucine N-alkyl amide (CSP 1). The enantioselectivities exerted by CSP 2 were much greater than those exerted by CSP 1. In addition, racemic N-(3,5-dimethoxybenzoyl)-a-mino N,Ndiethyl amides were resolved much better than the corresponding N-(3,5-dimethoxybenzoyl)-a-mino N-propyl amides and esters on both CSPs. Based on these results, a chiral recognition mechanism utilizing the π-π donor-acceptor interaction and the two hydrogen bondings between the CSP and the analyte was proposed.

• Bulletin of the Korean Chemical Society
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• 제8권4호
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• pp.257-260
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• 1987

The asymmetric reduction of representative prochiral ${\alpha},{\beta}$-acetylenic ketones with a new chiral borohydride reducing agent, potassium 9-0-(1,2: 5,6-Di-O-isopropylidene-${\alpha}$ -D-glucofuranosyl)-9-boratabicyclo[3.3.1]nonane, 1, in THF at $-78^{\circ}C$ was studied. Structurally different acetylenic ketones such as internal ${\alpha},{\beta}$-acetylenic ketones $RC {\equiv} CCOCH_3$ and terminal ${\alpha},{\beta}$-acetylenic ketones $HC {\equiv} CCOR$ were chosen. Thus, the reduction of internal ${\alpha},{\beta}$-acetylenic ketones yields the corresponding propargyl alcohols, such as 67% ee for 3-hexyn-2-one, 75% ee for 5-methyl-3-hexyn-2-one, 86% ee for 5,5-dimethyl-3-hexyn-2-one, 74% ee for 3-nonyn-2-one and 61% ee for 4-phenyl-3-butyn-2-one. Terminal ${\alpha},{\beta}$-acetylenic ketones, such as 3-butyn-2-one, 1-pentyn-3-one, 4-methyl-1-pentyn-3-one and 1-octyn-3-one, are reduced to the corresponding alcohols with 59% ee, 17% ee, 44% ee and 12% ee of optical induction respectively. With one exception (4-methyl-1-pentyn-3-one), all propargyl alcohols obtained are enriched in R-enantiomers.

• 분석과학
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• 제36권4호
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• pp.143-151
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• 2023

Considering the greater role of α-amino acids in our daily lives, the enantiomer resolution of seven α-amino acids derivatized with fluorogenic reagent (4-fluoro-7-nitro-2,1,3-benzoxadiazole, NBD-F) by chiral HPLC on amylose or cellulose trisphenylcarbamate derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence (FL) detection was performed. The degree of enantioseparation and resolution was affected by nature and selector backbones of the CSPs as well as the kind of amino acids. Baseline enantiomer separation and resolutions were observed for the enantiomers of all analytes as NBD derivatives especially on coated type amylose tris(3,5-dimethylphenylcarbamate) derived CSPs (Chiralpak AD-H and Lux Amylose-1). The other CSPs also showed good enantioselectivity except for the CSPs (Chiralpak IB, Chiralcel OD-H and Lux Cellulose-1) having cellulose tris(3,5-dimethylphenylcarbamate) as chiral selectors. The developed analytical chiral method was applied to determine the enantiomeric purity of seven commercially available L-α-amino acids and the impurities as D-forms were found to be in the range 0.08-0.87 %, respectively. The intra- and interday accuracy and precision assays showed high accuracy and precision of the developed analytical method. This chiral HPLC method for the enantiomer resolution of amino acids using fluorescent derivatization could be useful for the determination of enantiomeric purity of pharmaceuticals and biological study for amino acid type compounds among chiral drugs.

• 대한화장품학회지
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• 제49권2호
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• pp.141-146
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• 2023

라세미 혼합물 (헤미에스테르)의 키랄 순도를 효율적으로 측정하기 위한 방법으로 이작용기 (티오우레아와 3차 아민)를 갖는 키랄 이동제 (3)에 대한 연구이다. 다양한 헤미에스테르와 키랄 이동제 (3)의 결합으로 형성된 부분 입체 이성질체에 의해서 헤미에스테르의 메톡시 양성자의 신호가 분명하게 분리되었다. ¹H NMR에서 헤미에스테르의 거울상 이성질체에 대한 분명한 신호 분리는 헤미에스테르의 카르보닐기와 키랄 이동제 (3)의 이작용기(티오우레아와 3차 아민) 사이의 수소 결합에 기인한다. 본 연구는 키랄 이동제 (3)를 사용하여 헤미에스테르의 키랄 순도를 빠르고 간단하게 결정할 수 있는 방법을 제공한다.

• BMB Reports
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• 제32권5호
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• pp.480-485
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• 1999

Tyrosine phenol-lyase of thermophilic Symbiobacterium sp. SC-1, which is obligately and symbiotically dependent on thermophilic Bacillus sp. SK-1, was purified and characterized. The enzyme is composed of four identical subunits and contains approximately 1 mol of pyridoxal 5'-phosphate (PLP) per mol subunit as a cofactor. The enzyme showed absorption maxima at 330 and 420 nm, and lost this absorption profile by treatment with phenylhydrazine. The apparent dissociation constsnt, $K'_D$, for PLP was determined with the apoenzyme to be about $1.2\;{\mu}M$. The isoelectric point was 4.9. The optimal temperature and pH for the $\alpha,\beta$-elimination of L-tyrosine were found to be $80^{\circ}C$ and pH 8.0, respectively. The substrate specificity of the enzyme was very broad: L-amino acids including L-tyrosine, 3,4-dihydroxyphenyl-L-alanine (L-DOPA), L-cysteine, L-serine, S-methyl-L-cysteine, $\beta$-chloro-L-alanine, and S-(o-nitrophenyl)-L-cysteine all served as substrates. D-Tyrosine and D-serine were also decomposed into pyruvic acid and ammonia at rates of 7% and 31% relative to their corresponding L-enantiomers, respectively. D-Alanine, which was inert as a substrate in a, $\beta$-elimination, was the only D-amino acid racemized by the enzyme. The $K_m$ values for L-tyrosine, L-DOPA, S-(o-nitrophenyl)-L-cysteine, $\beta$-chloro-L-alanine, and S-methyl-L-cysteine were 0.19, 9.9, 0.36, 12, and 5.5 mM, respectively.

• Biomolecules & Therapeutics
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• 제15권1호
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• pp.40-45
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• 2007

The vascular relaxant effects on isolated rat aorta of amlodipine camsylates (S-, R-enantiomer, and R/S-racemate), were evaluated and compared with that of S-amlodipine besylate. Furthermore, antihypertensive effects were measured in spontaneously hypertensive rat (SHR). The S-amlodipine camsylate concentration-dependently inhibited $Ca^{2+}$-induced contraction of rat aorta with a very slow onset of action (reached its maximum at 3.5h; $ED_{50}:\;1.50\;{\pm}\;0.24$ nM), having a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{50}:\;3.36\;{\pm}\;0.91\;nM)$ and similar to those of S-amlodipine besylate $(ED_{50}:\;1.44\;{\pm}\;0.14\;nM)$, whereas the R-amlodipine camsylate has 590-fold lower vasorelaxant activity $(ED_{50}:\;886.4\;{\pm}\;49.7\;nM)$. In SHR, orally administered S-amlodipine camsylate produced a dose-dependent and long-lasting (>>10 h) antihypertensive effect $(ED_{20}:\;0.89\;mg/kg)$, with a potency 2-fold higher than those of R/S-amlodipine camsylate $(ED_{20}:\;1.82\;mg/kg)$ and similar to those of S-amlodipine besylate $(ED_{20}:\;0.71\;mg/kg)$. In contrast, the R-amlodipine camsylate has no effect even-though administrated high concentration 10 mg/kg. These results suggest that S-amlodipine camsylate has the potency and long-lasting antihypertensive activity as single enantiomer drug, and its antihypertensive effect is not significantly different to that of S-amlodipine besylate.

• Korean Chemical Engineering Research
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• 제48권4호
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• pp.515-518
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• 2010

$Chirobiotic^{(R)}$ T HPLC 컬럼을 이용하여 D, L-트립토판을 분리하였다. 이동상으로 메탄올과 증류수를 각각 70/30, 80/20, 90/10의 비율로 사용하고 체류시간을 비교하기 위해 온도를 25, 40, $55^{\circ}C$로 변화시켰다. 이동상 조성비를 변화시켜 D-트립토판과 L-트립토판의 체류시간 차이를 조사하였다. 선택도와 분리도, 컬럼의 효율성을 체류시간 관점에서 계산하여 최적의 분리 조건을 찾는 실험을 하였다. 이동상에서 메탄올의 양이 감소함에 따라 트립토판 체류시간이 짧아지고, 컬럼의 온도가 증가함에 따라 체류시간도 감소한다. 메탄올과 증류수의 비가 70/30일 때와 온도가 $25^{\circ}C$일 때 가장 좋은 선택도와 분리도를 얻었다.

• BMB Reports
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• 제42권1호
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• pp.47-52
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• 2009

Alanine racemase catalyzes the interconversion of L-alanine and D-alanine and plays a crucial role in spore germination and cell wall biosynthesis. In this study, alanine racemase produced by Bacillus anthracis was expressed and purified as a monomer in Escherichia coli and the importance of lysine 41 in the cofactor binding octapeptide and tyrosine 270 in catalysis was evaluated. The native enzyme exhibited an apparent $K_m$ of 3 mM for L-alanine, and a $V_{max}$ of $295\;{\mu}moles/min/mg$, with the optimum activity occurring at $37^{\circ}C$ and a pH of 8-9. The activity observed in the absence of exogenous pyridoxal 5'-phosphate suggested that the cofactor is bound to the enzyme. Additionally, the UV-visible absorption spectra indicated that the activity was pH independece, of VV-visible absorption spectra suggests that the bound PLP exists as a protonated Schiff's base. Furthermore, the loss of activity observed in the apoenzyme suggested that bound PLP is required for catalysis. Finally, the enzyme followed non-competitive and mixed inhibition kinetics for hydroxylamine and propionate with a $K_i$of $160\;{\mu}M$ and 30 mM, respectively.

• Korean Chemical Engineering Research
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• 제47권1호
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• pp.54-58
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• 2009

Ketoprofen과 Ibuprofen은 비스테로이드 계통의 진통 및 소염제로서 관절염 등을 위한 진통제나 해열제로 이미 널리 사용되고 있다. 그러나 이 두 물질이 치료약으로 사용될 때 (S)-ketoprofen과 (S)-ibuprofen은 약리학적으로 항염증 작용을 하며 (R)-ketoprofen과 (R)-ibuprofen은 약효가 없거나 부작용을 일으키는 문제점을 가지고 있다. 본 연구에서는 Ketoprofen과 Ibuprofen을 Kromasil HPLC 칼럼을 사용하여 이동상 조성비(hexane/t-BME/acetic acid)와 온도 변화($25{\sim}55^{\circ}C$)가 분리에 미치는 영향을 실험하였다. 분리특성은 선택도, 분리도, 이론단수 그리고 용량인자와 절대온도의 역수사이의 관계에서 계산된 엔탈피 변화 ${\Delta}H$에서 Ketoprofen과 Ibuprofen의 kromasil HPLC column 고정상과의 상호작용의 크기를 열역학적으로 검토하였다. 온도 $25^{\circ}C$, 이동상 조성비(hexane/t-BME/acetic acid) 80/20/0.1에서 선택도, 분리도, 이론단수 엔탈피 수치가 높게 나타났다.

• Journal of Microbiology and Biotechnology
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• 제14권1호
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• pp.97-104
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• 2004

Water-sludge bacteria were screened to find a lipase enantioselectively hydrolyzing itraconazole precursor, which is well known as the starting material of antifungal drug agents. A bacterial strain was isolated and identified as Acinetobacter junii SY-01. After the strain was cultivated, the enzyme was purified 39.4-fold using ultrafiltration and gel filtration through a Sephadex G-100 chromatographic column and the activity yield was 34.9%. The molecular weight of the enzyme was about 40 kDa, as measured by SDS-PAGE, and the optimum pH was 7.0- 9.0 and stable at pH 6.0- 9.0. The optimum temperature was 45- $5^{\circ}C$, and 73% of the enzymes activity remained after incubation at 70% for 1 h. Enzyme activity was enhanced by gall powder, sodium deoxycholate, a cationic detergent Tween 80, and a non-ionic detergent Triton X-100, but was markedly inhibited by metal ions such as $Hg^{2＋},Cu^{2＋},Ni^{2＋}/,Ca^{2＋}$, and an anionic-surfactant sodium dodecylsulfate. The $K_{m}$ values for (R)- and (S)-enantiomers of the itraconazole precursor were 0.385 and 21.83 mM, respectively, and the $V_{max} values ($\mu$Mㆍmin^{-1}.)$ were 6.73 and 6.49, respectively. The acetyl group among the different acyl moieties of itraconazole precursor showed the highest enantioselectivity for the hydrolysis by the Acinetobacter junii SY-01 lipase, and the lipase from Acinetobacter junii SY-01 displayed better enantioselectivity than that of commercially available lipases and esterases.