• Biotechnology and Bioprocess Engineering:BBE
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• v.2 no.2
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• pp.117-121
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• 1997

Glutamic acid can be crystallized inside cation exchange column when displacer NaOH concentration is high enough to concentrate displaced glutamic acid beyond its solubility limit. Resulting crystal layer of glutamic acid was moved with liquid phase through the column, and thus could be eluted from the column and recovered in fraction collector. For the purpose of enhancing crystal recovery, effects of operating parameters on the crystal formation were investigated. The increase in the degree of crosslinking of resin favored crystal recovery because of its low degree of swelling. Higher concentration of displacer NaOH was advantageous. If NaOH concentration is too high, however, crystal recovery was lowered due to the solubility-enhancing effects of high pH and ionic strength. The decrease of mobile phase flow rate enhanced crystal recovery because enough time to attain local equilibrium could be provided, but film diffusion would control the overall crystal formation with extremely low flow rate. Lower temperature reduced solubility of glutamic acid and thus favored crystal formation unless the rate of ion exchange was severely reduced. The ion exchange operated by displacement mode coupled with crystallization was advantageous in reducing the burden of further purification steps and in preventing purity-loss resulted from overlapping between adjacent bands.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.645-651
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• 2015

This paper presents an experimental study on the freeze drying process for poly ${\gamma}$ glutamic acid. The physical properties of poly ${\gamma}$ glutamic acid are measured during the freeze-drying process. The moisture contents of poly ${\gamma}$ glutamic acid according to the glass transient temperature are obtained by DSC (Differential Scanning Calorimetry) analysis. The end point of primary drying for the poly ${\gamma}$ glutamic acid with a thickness of 3 mm is obtained by measuring the thickness of the dried layer, the amount of moisture evaporation, the moisture content, and the pressure in the drying vacuum chamber during the freeze-drying process. By considering the variation in the glass transient temperature with respect to the moisture content of the material, a control schedule for the heating plate temperature is suggested during the secondary drying process.

• Korean journal of food and cookery science
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• v.29 no.6
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• pp.671-677
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• 2013

The objective of this study was to examine the levels of free amino acids and identify the correlation between ${\gamma}$-aminobutyric acid (GABA)and L-glutamic acid contents in Kimchi during fermentation. During 2 weeks of fermentation, the acidity of Kinchi increased, i.e., the pH level decreased from 5.24 to 4.40. The content of amino acids determined using HPLC differed significantly (p < 0.05) during 7 weeks of fermentation. Over the 7 weeks of fermentation, the content of most free amino acids increased in the order L-valine > L-glutamic acid > L-glycine, except L-methionine decreased. Initially, the GABA content was found to be $72.43{\mu}M/100g$ fresh weight (fw), and it increased to $229.06{\mu}M/100g$ fw after 7 weeks. This rapid increase in the GABA content in the initial stage is considered to be due to L-glutamic acid. However, during the period of 0~7 weeks, no correlations were found between the L-glutamic acid and GABA contents.

• Applied Biological Chemistry
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• v.36 no.3
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• pp.184-190
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• 1993

The effect of ${\delta}-aminolevulinic\;acid$ (ALA) biosynthetic precursors and related compounds on the ALA productivity from a strain of Rhodobacter sphaeroides has been examined in vivo and in vitro systems. The relative ratios of ALA productivities by $C_{4}$- pathway to that by $C_{5}$-pathway in vivo and in vitro systems were 0.78 and 1.37, respectively. Although the expression rates of $C_{4}-$ and $C_{5}-pathways$ in cell-free systems prepared after precursors supplemented cultivations were increased 1.35 and 1.52 folds, respectively, the rate increase of $C_{4}-pathway$ was accompanied by the rate decrease of the $C_{5}-pathways$, and vice versa, as that the rates of both $C_{4}-$ and $C_{5}-pathways$ were lowered to be 0.91, 0.83, respectively. The order of cellular uptake rates of ${\gamma}-glutamyl$ derivatives relative to that found with L-glutamic acid were shown to be D-glutamic acid, 0.55: D-glutamine, 0.5: L-glutamine, 0.4: ${\gamma}-L-glutamyl$ ethylester, 0.3: GSH and Glu-pNA, 0. L and D configurations of glutamine were indicated as better substrates in vivo for ALA yields than those of glutamic acid, respectively.

• KSBB Journal
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• v.11 no.5
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• pp.606-612
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• 1996

A specific ammino auid in a mixture can be crystallized inside an ion exchange column when displacer concentration is high enough to concentrate the amino acid in a pure band beyond its solubility limit. Glutamic acid formpd a discrete crystal layer in a cation exchanger column by operating displacement development mode and using a high concentration of displacer NaOH. The glutamic acid crystal formed was eluded from the column with the effluent stream and collected in a fraction collector. When 1.0 M of NaOH was used as a displacer, more than 60% of the loaded glutamic acid was recovered as crystal. The continuous crystallization and dissolution of crystal occurred, resulting in apparent movement of the crystal along the column without clogging or pressure increase. NaOH was proved a better displacer than NaCl because hydroxide ions neutralized hydrogen ions released from the resin and thus reduced the number of hydrogen ion competing with sodium ion for re-adsorption. The displacement development process coupled with crystallization provided higher concentration and recovery of glutamic acrid than conventional chromatography.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.125-131
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• 2007

Amino acid and fatty acid compositions of the physiological activity substance in the seed and pulpy substance of feral peach (Prunus persica Batsch var. davidiana Max.) were analyzed for the use as an biohealth functional processed products. The proximate compositions in the vacuum freeze dried seed and pulpy substance of feral peach were carbohydrate 63.92% and 75.11%, crude protein 27.85% and 12.77%, moisture 3.61% and 4.69%, crude fat 1.21% and 4.80%, crude ash 3.41% and 2.63%, respectively. Total amino acid contents in the protein of feral peach seed were 3,444.35 mg%, and the major amino acids were aspartic acid(681.10 mg%), glutamic acid(495.48 mg%), alanine(283.66 mg%), serine(251.36 mg%), proline(229.80 mg%), lysine(192.31 mg%) and leucine(191.34 mg%), respectively. Total amino acid contents in the protein of feral peach pulpy substance were 1,064.02 mg%, and the major amino acids followed aspartic acid(250.15 mg%), glutamic acid(129. 63 mg%), lysine, proline, leucine, alanine and serine, in a decreasing order. The richest total amino acid content contained in feral peach seed and pulpy substance was aspartic acid, followed by glutamic acid. The amount of free amino acids of feral peach seed were 6,215.34 ms%, and the major free amino acids were glutamic acid(827.25 mg%), threonine, valine and $\beta-aminobutyric$ acid, respectively. Free amino acid contents of pulpy substance were 683.82 mg%, and the major free amino acids were glutamic acid(339.49 mg%), serine proline, alanine and $\gamma-amino-n-butyric$ acid. Especially, in the case of glutamic acid, it was highest. The compositions of major total fatty acid in the lipid feral peach (Prunus persica Batsch var. davidiana Max.) seed and pulpy sabstance were linoleic acid($C_{18:2}$, n-6) and linolenic acid($C_{18:3}$, n-3), particularly.

• Journal of Photoscience
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• v.9 no.2
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• pp.33-36
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• 2002

In vertebrate rhodopsins the glutamic acid at position 113 serves as a counterion to stabilize the protonated retinylidene Schiff base linkage and to shift the spectrum to the visible region. Invertebrate rhodopsins and retinochrome have the amino acid residue different from glutamic acid or asparatic acid at this position and therefore, these pigments may have a counterion at different position. We first investigated the counterion in retinochrome by site specific mutagenesis. The results showed that the counterion is the glutamic acid at position 181, where almost of all the pigments including vertebrate and invertebrate rhodopsins in the rhodopsin family have a glutamic acid or an aspartic acid. In vertebrate rhodopsins, however, Glu 181 does not act as a counterion, and the red-sensitive cone pigments have a histidine at this position, which serves as a chloride-binding site for red-shift of the absorption spectrum. These findings suggested that the role of Glu181 as a counterion may be weakened by the newly acquired counterion at position 113. Taken together with our recent studies on an invertebrate-type rhodopsin, the rhodopsin diversity was discussed from viewpoint of counterion.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.14 no.2
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• pp.66-71
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• 1981

In order to study the decomposition process of glycogen and protein of oyster during fermentation with salt, and the relationship between their breakdown products, the amounts of free reducing sugars and lactic acid were determined, and amino acid compositions were analysed. In addition, the amount of the available lysine which may help us to estimate the reaction of the free reducing sugars with the free amino acids was also determined. Glycogen and protein were gradually decomposed to free reducing sugars and lactic acid, and free amino acids, respectively, and the available lysine was slightly decreased during the fermentation process. Glutamic acid, aspartic acid, lysine and proline were relatively rich in the amino acid com-position of raw oyster protein while amino acids such as tryptophan, methionine, histidine and tyrosine were poor. It was noted that the decreased amino acids in the protein from the fermented oyster were valine, histine, isoleucine and lysine. As a respect to the free amino acids, proline, taurine, glycine, glutamic acid and alanine were abundant in the raw oyster and reached up to $69\%$ of the total fret amino acids. In the fermented oyster, proline, glutamic acid, glycine, alanine, aspartic acid and lysine were prevalently contained and marke about $65\%$ of the total free amino acids. The contents of free amino acids such as lysine, arginine, aspartic acid, glutamic acid, cysteine, isoleucine and tyrosine increased during fermentation while those of taurine, proline and leucine decreased.

• Journal of Life Science
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• v.31 no.5
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• pp.520-526
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• 2021

Microbial protein is one of the sources of protein in the rumen and can also be the source of glutamate production. Glutamic acid is used as fuel in the metabolic reaction in the body and the synthesis of all proteins for muscle and other cell components, and it is essential for proper immune function. Moreover, it is used as a surfactant, buffer, chelating agent, flavor enhancer, and culture medium, as well as in agriculture for such things as growth supplements. Glutamic acid is a substrate in the bioproduction of gamma-aminobutyric acid (GABA). This review provides insights into the role of glutamic acid and glutamic acid-producing microorganisms that contain the glutamate decarboxylase gene. These glutamic acid-producing microorganisms could be used in producing GABA, which has been known to regulate body temperature, increase DM intake and milk production, and improve milk composition. Most of these glutamic acid and GABA-producing microorganisms are lactic acid-producing bacteria (LAB), such as the Lactococcus, Lactobacillus, Enterococcus, and Streptococcus species. Through GABA synthesis, succinate can be produced. With the help of succinate dehydrogenase, propionate, and other metabolites can be produced from succinate. Furthermore, clostridia, such as Clostridium tetanomorphum and anaerobic micrococci, ferment glutamate and form acetate and butyrate during fermentation. Propionate and other metabolites can provide energy through conversion to blood glucose in the liver that is needed for the mammary system to produce lactose and live weight gain. Hence, health status and growth rates in ruminants can be improved through the use of these glutamic acid and/or GABA-producing microorganisms.

• The Korean Journal of Food And Nutrition
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• v.25 no.3
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• pp.677-684
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• 2012

A bacterium strain GS-2 isolated from the Korean traditional seasoning food, Chungkookjang and was determined to produce large amounts of ${\gamma}$-PGA with high productivity when provided with simple nutrients (L-glutamic acid 2.0%, glucose 1.0%, $NH_4Cl$ 0.5%, $KH_2PO_4$ 0.05%, $MgSO_4{\cdot}7H_2O$ 0.01%, pH 7.0). In this study, the culture medium for this strain was optimized for the production of ${\gamma}$-PGA. The Bacillus subtilis GS-2 required supplementation with L-glutamic acid and other nutrients for maximal production of ${\gamma}$-PGA. The optimal culture conditions for ${\gamma}$-PGA production were a 48 hr culture time, a temperature of $33^{\circ}C$ and initial pH of 6.5 by rotary shaking (220 rpm). A maximum ${\gamma}$-PGA production of 31.0 $g/{\ell}$ was obtained with L-glutamic acid (30 $g/{\ell}$), sucrose (the main carbon source, 30 $g/{\ell}$), $NH_4Cl$ (the main nitrogen source, 2.5 $g/{\ell}$), $KH_2PO_4$ (1.5 $g/{\ell}$) and $MgSO_4{\cdot}7H_2O$ (0.15 $g/{\ell}$) in the culture medium.