• Archives of Pharmacal Research
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• 제23권6호
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• pp.574-578
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• 2000

Protected $\alpha$-Phenyl glycine 17 and phenylalanine 18 and 19 have been synthesized through an efficient three-step sequence from the corresponding allyl ethers 5, 7, and 10. The key intermediate in this synthesis is the corresponding allylic amines prepared by reaction of allyl ethers with chlorosulfonyl isocyanate.

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권4호
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• pp.299-305
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• 2006

Aromatic L-amino acid transaminase is an enzyme that is able to transfer the amino group from L-glutamate to unnatural aromatic ${\alpha}-keto$ acids to generate ${\alpha}-ketoglutarate$ and unnatural aromatic L-amino acids, respectively. Enrichment culture was used to isolate thermophilic Bacillus sp. T30 expressing this enzyme for use in the synthesis of unnatural L-amino acids. The asymmetric syntheses of L-homophenylalanine and L-phenylglycine resulted in conversion yields of >95% and >93% from 150 mM 2-oxo-4-phenylbutyrate and phenylglyoxylate, respectively, using L-glutamate as an amino donor at $60^{\circ}C$. Synthesized L-homophenylalanine and L-phenylglycine were optically pure (>99% enantiomeric excess) and continuously pre-cipitated in the reaction solution due to their low solubility at the given reaction pH. While the solubility of the ${\alpha}-keto$ acid substrates is dependent on temperature, the solubility of the unnatural L-amino acid products is dependent on the reaction pH. As the solubility difference between substrate and product at the given reaction pH is therefore larger at higher temperature, the thermophilic transaminase was successfully used to shift the reaction equilibrium toward rapid product formation.

• EDISON SW 활용 경진대회 논문집
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• 제3회(2014년)
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• pp.103-113
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• 2014

Hydrophobicity is the key concept to understand the role of water in protein folding, protein self-assembly, and protein-ligand interaction. Conventionally, hydrophobicity of amino acids in a protein has been argued based on hydrophobicity scales determined for individual free amino acids, assuming that those scales are unaltered when amino acids are embedded in a protein. Here, we investigate how the hydrophobicity of constituent amino acids depends on the protein context, in particular, on the total charge and secondary structures of a protein. To this end, we compute and analyze the hydration free energy - free energy change upon hydration quantifying the hydrophobicity - of three short proteins based on the integral-equation theory of liquids. We find that the hydration free energy of charged amino acids is significantly affected by the protein total charge and exhibits contrasting behavior depending on the protein net charge being positive or negative. We also observe that amino acids in the central ${\beta}$-strand sandwiched by ${\beta}$-sheets display more enhanced hydrophobicity than free amino acids, whereas those in the ${\alpha}$-helix do not clearly show such a tendency. Our results provide novel insights into the hydrophobicity of amino acids, and will be valuable for rationalizing and predicting the strength of water-mediated interaction involved in the biological activity of proteins.

• Fisheries and Aquatic Sciences
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• 제4권4호
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• pp.192-196
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• 2001

Proopiomelanocortin (POMC) plays an essential role in the disease resistance system and is the precursor protein of biologically active peptides such as adrenocorticotropin (ACTH), $\alpha-melanocyte-stimulating$ hormone $(\alpha- MSH)$, $(\beta-melanocyte-stimulation hormone\;(\beta- MSH)$ and $\beta-endorphin$. We have isolated and sequenced two different forms of POMC cDNA, POMC-I and POMC-II, from a pituitary cDNA library of flounder. POMC-I cDNA consisted of 956 bp corresponding to deduced amino acids of 216 residues and POMC-II cDNA was 982 bp in length corresponding to 194 amino acids, respectively. The results of deduced amino acids analysis of the clones showed high sequence homology with previously reported POMCs amino acid sequences from various species. The homology between flounder POMC-I and -II is$57\%$ identity. We also constructed a phylogenetic tree based on POMC amino acid sequences.

• Bulletin of the Korean Chemical Society
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• 제24권12호
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• pp.1757-1762
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• 2003

The interrelation between retention factors of several L-amino acids and their physico-chemical and structural properties can be determined in chromatographic research. In this paper we describe a predictor for retention factors with various properties of the L-amino acids. Eighteen L-amino acids are included in this study, and retention factors are measured experimentally by RP-HPLC. Binding energy ($E_b$), hydrophobicity (log P), molecular refractivity (MR), polarizability (${\alpha}$), total energy ($E_t$), water solubility (log S), connectivity index (${\chi}$) of different orders and Wiener index (w) are theoretically calculated. Relationships between these properties and retention factors are established, and their predictive and interpretive ability are evaluated. The equation of the relationship between retention factors and various descriptors of L-amino acids is suggested as linear and multiple linear form, and the correlation coefficients estimated are relatively higher than 0.90.

• 공업화학
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• 제4권2호
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• pp.254-263
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• 1993

아미노산공업은 추출법으로부터 합성법, 발효법으로 발전되어 왔다. 현재 일부의 아미노산(L-cytine, L-tyrosine 등)은 추출법으로 제조하고 있지만 대부분의 아미노산은 합성법, 발효법에 의해서 생산되고 있다. 이중 합성법은 유독의 시안화수소를 이용하며, 산 및 알카리에 의한 가수분해과정에서 다량의 공업폐수가 발생한다. 이러한 관점에서 환경에 미치는 영향을 고려하여 개량된 새로운 합성법이 요구되고 있다. 본 총설에서는 근년에 주목받고 있는 phenyl alanine의 새로운 합성법에 대해서 소개하고 보다 특수한 아미노산을 합성하기 위해서 전구체인 ${\alpha}$-케토산 유도체의 합성법에 대해서 최근의 연구결과를 소개한다.

• EDISON SW 활용 경진대회 논문집
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• 제5회(2016년)
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• pp.163-166
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• 2016

Hydrophobicity is the key concept to understand the water plays in protein folding, protein aggregation, and protein-protein interaction. Traditionally, the hydrophobicity of protein is defined based on the scales of the hydrophobicity of residue, assuming that the hydrophobicity of free amino acids is maintained. Here, we explore how the hydrophobicity of constituting amino acids in protein rely on the protein context, in particular, on the total charge and secondary structures of a protein. To this end, we calculate and investigate the hydration free energy of three short proteins based on the integral-equation theory of liquids. We find that the hydration free energy of charged amino acids is significantly affected by the protein total charge and exhibits contrasting behavior depending on the protein total charge being positive or negative. We also observe that amino acids in the ${\beta}-sheets$ display more enhanced the hydrophobicity than amino acids in the loop, whereas those in the ${\alpha}-helix$ do not clearly show such a tendency. And the salt-bridge forming amino acids also exhibit increase of the hydrophobicity than that with no salt bridge. Our results provide novel insights into the hydrophobicity of amino acids, and will be valuable for rationalizing and predicting the strength of water-mediated interaction involved in the biological activity of proteins.

• 통합자연과학논문집
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• 제8권2호
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• pp.111-116
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• 2015

Liquid chromatographic enantiomer separation of ${\alpha}$-amino acid esters as nitrobenzoxadiazole (NBD) derivatives was performed using several chiral stationary phases (CSPs) based on polysaccharide derivatives under fluorescence detection. For enantiomer separation by normal HPLC, the non-aqueous derivatization method of ${\alpha}$-amino acid esters for NBD analytes was introduced. Among the six CSPs used in this study, the performance of Chiralpak IA was superior for enantiomer resolution of NBD derivatives of several ${\alpha}$-amino acid methyl esters. Also the convenient analytical method using polysaccharide-derived CSPs developed in this study was applied to determine the optical purity of ${\alpha}$-amino acids esters. It was investigated that the enantiomeric impurity levels of 0.02-1.73% were found after determination of enantiomeric purities of several commercially available L-amino acid methyl esters. It is expected to be quite useful for enantiomer separation of other ${\alpha}$-amino acid esters as NBD derivatives by normal HPLC.

• 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.

• 한국식품과학회지
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• 제33권2호
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• pp.238-244
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• 2001

본 연구에서는 가열온도에 따른 영귤 과즙의 성분 변화를 조사하여 영귤 가공의 기초 자료로 사용하고자 총산도, $^{\circ}Brix$, pH, 유기산, 유리 아미노산, 비타민 C, 나린진, 헤스페리딘, 네오헤스페리딘 함량, 향기 성분을 분석하였다. 영귤 과즙에는 유기산이 oxalic, citric, malic acid가 존재하였으며, citric acid가 92.8-94.1%로서 대부분을 차지하였고, 그외 malic acid와 oxalic acid 순으로 소량 함유되어 있는 것으로 나타났다. 가열온도가 $40^{\circ}C$에서 $90^{\circ}C$로 증가할수록 총 유기산의 함량은 약간 감소하는 경향을 보여, 가열 전에 비하여 $90^{\circ}C$로 가열 후 약 0.3%가 감소하였다. 영귤 과즙에 존재하는 유리 아미노산은 alanine, threonine, proline, aspargine과 aspartic acid, serine, tyrosine, tryptophane이 주요 유리 아미노산이었다. Arginine, valine, glycine, isoluecine, leucine, histidine등은 소량 존재하였다. 가열함에 따라 유리 아미노산 총량과 개개의 유리 아미노산 함량은 감소하였다. 영귤 과즙에는 비타민 C가 21.3mg% 존재하였으나, 가열함에 따라 점차 감소하여 $90^{\circ}C$에서는 17.3mg%가 존재하였다. 영귤 과즙에 존재하는 나린진, 헤스페리딘, 네오헤스페리딘 함량은 304mg%였으며, 가열함에 따라 297.0mg%로 약간 감소하였다. 영귤 과즙 향기 성분 중 limonene이 가장 많고, ${\gamma}-terpinene,\;{\alpha}-phellandrene$, myrcene, ${\alpha}-pinene$ 등이 주요 향기 구성 성분으로 나타났다. ${\alpha}-Thujene$는 가열하기 전 과즙에는 존재하였으나, $50^{\circ}C$ 이상 가열한 과즙에는 존재하지 않았다. 반면, ${\alpha}-terpinolene$, terpinene-1-ol, ${\beta}-terpineol$, $cis-{\beta}-terpineol$, ${\alpha}-muurolene$, bicyclo(3.2.0)hept-6-ene, mentha-1.4.8-triene 등은 가열하지 않은 원액과 $70^{\circ}C$까지 존재하지 않았으나, $90^{\circ}C$ 가열시에 새로 생성되었다.