• Journal of Microbiology
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• 제40권1호
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• pp.33-37
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• 2002

An enzymatic reaction for the production of D-alanine from D-aspartic acid and pyruvate as substrates by a thermostable D-amino acid aminotransferase (D-AAT) was investigated at various conditions In the temperature range of 40-70$\^{C}$ and pH range of 6.0-9.5. The D-AAT was produced with recombinant E. coli BL21, which hosted the chimeric plasmid pTLK2 harboring the D-AAT from the novel thermophilic Bacillus sp. LK-2. The enzyme reaction was shown to follow the Ping Pong Bi Bi mechanism. The K$\_$m/ values for D-aspartic acid and pyruvate were 4.38 mar and 0.72 mM, respectively. It was observed that competitive inhibition by D-alanine, the product of this reaction, was evident with the inhibition constant K$\_$i/ value of 0.1 mM. A unique feature of this reaction scheme is that the decorboxylation of oxaloacetic acid, one of the products, spontaneously produces pyruvate. Therefore, only a catalytic amount of pyruvate is necessary for the enzyme conversion reaction to proceed. A typical time-course kinetic study skewed that D-alanine up to 88 mM could be produced from 100 mM of D-aspartic acid with a molar yield of 1.0.

• Journal of Plant Biology
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• 제34권2호
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• pp.101-106
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• 1991

담배(N. glauca) 잎 절편 유래 callus 배양에 있어서 callus 생장 단계에 따라 nicotine 생성에 미치는 두 가지 auxin (2,4-D와 NAA)의 영향을 HPLC를 이용하여 조사하였다. 고농도($11.5\;\mu\textrm{M}$)의 2,4-D는 배양 4주째에, NAA는 배양 2주째에 nicotine 생성을 촉진시켜 최대함량을 나타내었고, 그 이후로는 감소하였다. 새성된 nicotine이 다른 alkaloid로 전환되었다. 한편, 전구물질로 알려진 L-arginine 또는 L-aspartic acid 첨가배양에서 저농도($1.5\;\mu\textrm{M}$)의 2,4-D는 고농도에 비해 nicotine 생성을 촉진시켰고, 저농도의 NAA는 고농도에 비해 억제시켰다. 그러나 L-aspartic acid 첨가배양에서 저농도의 NAA는 배양 5주까지 nicotine 생성을 촉진시켰다. 이와 같은 결과로부터 두 가지 auxin은 nicotine 생성에 대해 효과가 다르며, L-aspartic acid가 nicotine 생합성의 전구물질로서, 저농도의 NAA는 이 합성경로에 작용하여 nicotine 생성을 유도하였음을 추론할 수 있었다.

• Journal of Applied Biological Chemistry
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• 제57권3호
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• pp.251-254
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• 2014

$\small{L}$-arginine ($\small{L}$-Arg)을 짠맛 증강소재로 활용하기 위하여 전자혀 분석으로 $\small{L}$-Arg의 맛 특성을 조사하고, $\small{L}$-Arg의 강한 쓴맛을 억제하기 위하여 $\small{L}$-aspartic acid ($\small{L}$-Asp)을 혼합하였다. 0.4% NaCl 용액에 $\small{L}$-Arg과 $\small{L}$-Asp를 혼합하여 전자혀 시스템으로 분석한 결과 $\small{L}$-Arg과 $\small{L}$-Asp의 혼합을 다르게 한 경우, 동일한 $\small{L}$-Arg 농도에서 $\small{L}$-Asp의 비율이 감소함에 따라 NaCl의 짠맛 상승효과는 증가하였다. 관능평가에서 짠맛은 동일한 경향이었으며, $\small{L}$-Asp의 첨가로 $\small{L}$-Arg의 쓴맛이 억제되는 것을 확인하였다. 즉, $\small{L}$-Arg과 $\small{L}$-Asp 혼합물은 짠맛 증강소재로 활용될 수 있으며, $\small{L}$-Arg의 쓴맛을 상쇄하기 위한 최적의 혼합비율은 $\small{L}$-Arg : $\small{L}$-Asp =1.00:0.98-1.00 범위가 적합하였다.

• Translational and Clinical Pharmacology
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• 제26권3호
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• pp.134-140
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• 2018

This study aimed to develop a UPLC-MS/MS method for determining plasma levels of L-aspartic acid and L-asparagine and the activity of L-asparaginase. L-aspartic acid, L-asparagine, and L-aspartic acid-2,3,3-$d_3$ were extracted from human plasma by protein precipitation with sulfosalicylic acid (30%, v/v). The plasma samples were analyzed using an Imtakt Intrada amino acid analysis column with 25 mM ammonium formate and 0.5% formic acid in acetonitrile as the mobile phase with step gradient method at a flow rate of 0.5 mL/min. The injection volume was $5{\mu}L$, and the total run time was 15 min. Inter- and intra-batch accuracies (%) ranged from 96.62-106.0% for L-aspartic acid and 89.85-104.8%, for L-asparagine, and the coefficient of variation (CV%) did not exceed 7%. The validation results for L-aspartic acid and L-asparagine satisfied the specified criterion, however, the results for L-asparaginase activity assay showed a borderline validity. This study could be a foundation for further development of therapeutic drug monitoring systems using UPLC-MS/MS.

• Bulletin of the Korean Chemical Society
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• 제13권3호
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• pp.315-316
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• 1992

Sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-methoxyi minoacetamido]-4-methoxymethyl-2-azetidinone-1- sulfonate (2) was synthesized in fourteen steps from D-aspartic acid. Starting from D-aspartic acid, (3S,4R)-3-amino-1-t-butyldimethylsilyl-4-methoxym ethyl-2-azetidinone (12) was synthesized in ten steps. Acylation of the amino group of 12 with $2-amino-{\alpha}-(methoxyimino)-4-thiazoleacetic$ acid, desilylation, sulfonation, and ion exchange afforded sodium (3S,4R)-3-[2-(2-aminothiazol-4-yl)-(Z)-2-methoxyi minoacetamido]-4-methoxymethyl-2-azetidinone-1- sulfonate (2). This new ${\beta}-lactam$ compound 2 showed low antibacterial activities.

• Journal of Oral Medicine and Pain
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• 제14권1호
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• pp.43-55
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• 1989

The need of age estimation for identification was increased by complexity of society, and the tooth was used widely for age estimation because of less individual deviation than the other organ. The age estimation using the tooth had several methods. Recently, the one using the racemization of aminoacid in the tooth was admitted more accurate than the other methods, especially in old age. But, this study was not tried in our country, and I would report the result of experiment about age estimation using racemization of dentine. I selected 40-Whole dentine sample from extracted teeth, those were reserved in natural dried condition for 2 weeks~ 1year and calculated the estimation of age from the ratio of D-aminoacid and L-aminoacid (D/L ratio) using gaschromatography and the results were below. 1. The aminoacids showed apparent K/L ratio in dentine were aspartic acid, serine. 2. The aspartic acid showed the highest racemic rate and its rate was 0.0012$\pm$0.0003/yr. 3. The relation between the actual age and K/L ratio was very positive correlation(r+0.954) in the estimation of age using aspartic acid. 4. The deviation between the estimated age using D/L ratio of aspartic acid and actual age was $\pm$3.32.

• 한국미생물·생명공학회지
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• 제31권2호
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• pp.140-144
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• 2003

신호펩디드 가수분해는 모든 생물에 필수적인 단백질로 N-말단에 신호서열을 가진 단백질들의 신호서열을 잘라내는 효소로 serine과 lysine을 활성부위로 하는 특이한 dyad serine 효소류로 알려져있다. 최근에 신호펩디드 가수분해효소의 특성으로 새로운 항생제 이용 가능성 때문에 그 활성 메카니즘의 연구가 중요시되고 있다. 본 연구는 E. coli 신호펩디드 효소가 serine/lysine/aspartic acid로 하는 전형적인 triad serine 효소류의 메카니즘을 갖는다는 가정하에 Type Ⅰ 신호펩디드류의 하나인 E. coli에서 aspartic acid 99을 alanine으로 치환하여 효소의 enzymatic activity를 조사하였다. 그 결과 D99잔기는 E. coli Type Ⅰ 신호펩디드 효소의 활성메카니즘에 직접적으로 관여한다기보다는 그 효소를 구조적으로 안정화하는데 중요한 역할을 할 가능성이 있는 것으로 암시되어진다.

• Journal of Nutrition and Health
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• 제44권6호
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• pp.474-480
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• 2011

Calcium (Ca) is an essential element to maintain body homeostasis. However, many factors disturb calcium absorption. Aspartic acid chelated calcium (AAC) was synthesized by new methods using calcium carbonate and aspartic acid. This study was carried out to investigate the bioavailability of AAC in Ca-deficient rats. The experimental groups were as follows: NC; normal diet control group, CD-C; untreated control group of Ca-deficient (CD) rats, CD-$CaCO_3$; $CaCO_3$ treated group of CD rats, CD-AAC; AAC treated group of CD rats, and CD-SWC; and seaweed-derived Ca treated group of CD rats. The Ca content of various types of Ca was held constant at 32 mg/day, and the four CD groups were fed for 7 days after randomized grouping. Ca content in serum, urine, and feces within feeding periods were analyzed to confirm Ca absorption. Serum Ca content was significantly higher in the CD-AAC (11.24 mg/dL) and CD-SWC (10.12 mg/dL) groups than that in the CD-C (8.6 mg/dL) group 2 hours following the first administration. The Ca content in feces was significantly lower in the CD-AAC (35.4 mg/3 days) and CD-SWC (71.1 mg/3 day) groups than that in the CD-$CaCO_3$ (98.7 mg/3 days) group (p > 0.05). AAC had a 2.3-fold higher absorption rate of Ca than that of SWC. No differences in fibula length were observed in the NC and CD groups. The fibula weights of the CD-AAC (0.33 g) and CD-SWC (0.33 g) groups increased compared to those in the CD-C (0.27 g) group; however, no significant difference was observed between the CD groups. We conclude that bioavailability of AAC is higher than that of seaweed-derived Ca or inorganic Ca. Thus, these findings suggest the AAC has potential as a functional food material related to Ca metabolism.

• IMMUNE NETWORK
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• 제11권5호
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• pp.281-287
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• 2011

Background: Biodegradable polymers have increasingly been recognized for various biological applications in recent years. Here we examined the immunostimulatory activities of the novel poly(aspartic acid) conjugated with L-lysine (PLA). Methods: PLA was synthesized by conjugating L-lysine to aspartic acid polymer. PLA-nanoliposomes (PLA-NLs) were prepared from PLA using a microfluidizer. The immunostimulatory activities of PLA-NLs were examined in mouse bone marrow-derived dendritic cells (BM-DCs). Results: PLA-NLs increased the number of BM-DCs when added to cultures of GM-CSF-induced DC generation on day 4 after the initiation of cultures. Examination of the phenotypic properties showed that BM-DCs generated in the presence of PLA-NLs are more mature in terms of the expression of MHC class II molecules and major co-stimulatory molecules than BM-DCs generated in the absence of PLA-NLs. In addition, the BM-DCs exhibited enhanced capability to produce cytokines, such as IL-6, IL-12, TNF-${\alpha}$ and IL-$1{\beta}$. Allogeneic mixed lymphocyte reactions also confirmed that the BMDCs were more stimulatory on allogeneic T cells. PLA- NL also induced further growth of immature BM-DCs that were harvested on day 8. Conclusion: These results show that PLA-NLs induce the generation and functional activities of BM-DCs, and suggest that PLA-NLs could be immunostimulating agents that target DCs.

• Applied Biological Chemistry
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• 제15권1호
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• pp.35-40
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• 1972

The contents of free amino acids in deembryod brown rice of two varieties were investigated by amino acid autoanalizer in relation to specific gravity grade. The analytical methods of free amino acid were also discussed. 1) The lower the specific gravity of the unhulled rice the higher the content of total free amino acids in the deembryod brown rice, and the similar trend appears to hold on each amino acids. 2) Main free amino acids were serine+asparagine, glutamic acid, aspartic acid, alanine and valine, and maximum values of them were 7.3, 5.1, 4.0, 3.4, 0.9mg/100g rice, respectively. They consist about 85% of total free amino acids in most cases. 3) The contents of soluble nitrogen and free amino acids appear to be lower in high protein variety (IR 667) than in low protein variety (Jinhung). The percentage of free amino acid nitrogen to soluble nitrogen, however, appears to be higher in high protein variety (IR 667). 4) Alanine was much lower than aspartic acid in IR 667 having Indica blood while alanine appears to be higher than aspartic acid in Jinhung (Japonica rice) suggesting varietal difference in amino acid metabolism. 5) Threonine peak was overlaped with glutamine, and serine was with asparagine in this study.