• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.93-105
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• 2012

Activity coefficients and solubilities of L-Valine and L-Proline in aqueous solutions containing each of four electrolytes such as NaCl, KCl, $NaNO_3$ and $KNO_3$ were measured at 298.15 K. The measurements of activity coefficients were carried out in the electrochemical cell coupled with two ion-selective electrodes (cation and anion), and the solubilities were measured by the gravimetric analysis of saturated solutions in equilibrium with the solid phase of amino acid. The measured activity coefficients of electrolytes and amino acids were correlated with the theoretical thermodynamic model presented in the previous work [Korean Chem. Eng. Res. 48(4), 519(2010)]. It was found that the activity coefficients of amino acids and electrolytes described based on the our previous model were well agreeable with experimental data. Also the experimental solubility data of L-Valine and L-Proline were successfully correlated with the thermodynamic relation mentioned in the previous work.

• KSBB Journal
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• v.11 no.5
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• pp.613-621
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• 1996

The effects of important medium components such as carbon, nitrogen sources and amino acids on the production of cyclosporin A(CyA) were investigated in an immobilized fungal cell fermentation using Tolypocladium inflatum. As carbon sources in the synthetic medium, fructose and maltose stimulated CyA production remarkably compared to glucose when ammonium sulfate was supplemented as a nitrogen source. In the absence of ammonium sulfate in the medium, however, CyA biosynthesis was reduced considerably without regard to C-sources tested. Ammonium sulfate was found to be the best N-source, and also ammonium phosphate and ammonium citrate showed some positive effects on CyA production. Optimum concentration of ammonium sulfate was 10g/L, and supplementation of ammonium sulfate at the start of fermentation was found to be the most efficacious for maximal production of CyA. Among the constituent amino acids of cyclic peptide, CyA, L-valine had the most significant effect on the biosynthesis of CyA, and maximum CyA production was observed when 10 g/L of L-valine was initially added.

• Membrane Journal
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• v.13 no.2
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• pp.125-129
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• 2003

A remarkable separation performance of olefin/paraffin mixtures has been observed through facilitated olefin transport membranes consisting of silver ions dissolved in polymer matrices. In this research, valine, an amino acid, was introduced in poly (2-ethyl-2-oxazoline) (POZ)/$AgBF_4$ membranes to increase the separation performance. FT-IR spectra show that the cationic sites ($-NH_3^+$) of valine interact with the counter anion of the silver salt, resulting in the enhanced activity of the silver ions and consequently improved separation perfornance. Therefore, the $POZ/AgBF_4$ membranes containing valines exhibit the higher permeance as well as the higher selectivity of propylene/propane than those without valine.

• YAKHAK HOEJI
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• v.29 no.6
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• pp.375-379
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• 1985

The gas chromatographic behavior of optically active N-(N-benzoyl-L-valyl)-anilide used as stationary phase is described. N-(N-benzoyl-L-valyl)-anilide has been synthesized with good yield under mild condition via Schotten-Bauman process and coated on the Chromosorb W AW (80-100mesh) for the purpose of enantiomer separation. The behavior of this compound as optically active stationary phase for the separation of the enantiomers of N-TFA-D, L-amino acid isopropyl esters has been examined with respect to the correlation between the separation factors and column temperatures. All amino acid enantiomers examined were eluted within one hour and the elution pattern showed retention times increasing in the order of alanine, valine, leucine, threonine, proline and methionine.

• Journal of Microbiology and Biotechnology
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• v.29 no.8
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• pp.1288-1298
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• 2019

Bacterial ATP synthases drive ATP synthesis by a rotary mechanism, and play a vital role in physiology and cell metabolism. Corynebacterium glutamicum is well known as an industrial workhorse for amino acid production, and its ATP synthase operon contains eight structural genes and two adjacent genes, cg1360 and cg1361. So far, the physiological functions of Cg1360 (GenBank CAF19908) and Cg1361 (GenBank CAF19909) remain unclear. Here, we showed that Cg1360 was a hydrophobic protein with four transmembrane helices (TMHs), while no TMH was found in Cg1361. Deletion of cg1360, but not cg1361, led to significantly reduced cell growth using glucose and acetic acid as carbon sources, reduced F1 portions in the membrane, reduced ATP-driven proton-pumping activity and ATPase activity, suggesting that Cg1360 plays an important role in ATP synthase function. The intracellular ATP concentration in the ${\Delta}cg1360$ mutant was decreased to 72% of the wild type, while the NADH and NADPH levels in the ${\Delta}cg1360$ mutant were increased by 29% and 26%, respectively. However, the ${\Delta}cg1361$ mutant exhibited comparable intracellular ATP, NADH and NADPH levels with the wild-type strain. Moreover, the effect of cg1360 deletion on L-valine production was examined in the L-valine-producing V-10 strain. The final production of L-valine in the $V-10-{\Delta}cg1360$ mutant reached $9.2{\pm}0.3g/l$ in shake flasks, which was 14% higher than that of the V-10 strain. Thus, Cg1360 can be used as an effective engineering target by altering energy metabolism for the enhancement of amino acid production in C. glutamicum.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.4
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• pp.523-528
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• 2013

This study investigates the effects of three branched-chain amino acids (BCAA; valine, leucine, and isoleucine) on the in vitro ruminal fermentation of wheat straw using batch cultures of mixed ruminal microorganisms. BCAA were added to the buffered ruminal fluid at a concentration of 0, 2, 4, 7, or 10 mmol/L. After 72 h of anaerobic incubation, pH, volatile fatty acids (VFA), and ammonia nitrogen ($NH_3$-N) in the ruminal fluid were determined. Dry matter (DM) and neutral detergent fiber (NDF) degradability were calculated after determining the DM and NDF in the original material and in the residue after incubation. The addition of valine, leucine, or isoleucine increased the total VFA yields ($p{\leq}0.001$). However, the total VFA yields did not increase with the increase of BCAA supplement level. Total branched-chain VFA yields linearly increased as the supplemental amount of BCAA increased (p<0.001). The molar proportions of acetate and propionate decreased, whereas that of butyrate increased with the addition of valine and isoleucine (p<0.05). Moreover, the proportions of propionate and butyrate decreased (p<0.01) with the addition of leucine. Meanwhile, the molar proportions of isobutyrate were increased and linearly decreased (p<0.001) by valine and leucine, respectively. The addition of leucine or isoleucine resulted in a linear (p<0.001) increase in the molar proportions of isovalerate. The degradability of NDF achieved the maximum when valine or isoleucine was added at 2 mmol/L. The results suggest that low concentrations of BCAA (2 mmol/L) allow more efficient regulation of ruminal fermentation in vitro, as indicated by higher VFA yield and NDF degradability. Therefore, the optimum initial dose of BCAA for in vitro ruminal fermentation is 2 mmol/L.

• Proceedings of the Korean Aquaculture Society Conference
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• 2003.10a
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• pp.67-67
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• 2003

Dorsal aorta cannulated rainbow trout averaging 505 $\pm$ 6.5g (Mean $\pm$ SD) were divided into 7 groups (5 fish per group). Twenty four hour post feeding, cannulated fish were intubated with one of seven L-amino acid diets containing graded levels of Valine (Val. : 0.45, 0.95, 1.20, 1.45, 1.70, 1.95 or 2.45%) at 1% of body weight. Blood samples were taken at 0, 5 and 24hr after feeding the experimental diets. Post-prandial (5h after feeding) plasma-free Valine concentrations (PPval.) increased linearly from fish fed diets containing Valine between 0.45 and 1.45%, but the concentration remained constant from fish fed diets containing valine between 1.45 and 2.45%. Post-absorptive (24h after feeding) plasma free valine concentrations (PAval) increased linearly from fish fed diets containing valine between 0.45 and 1.45%, but the concentration remained constant from fish fed diets containing valine between 1.45 and 1.95%. Using the broken-line model analysis, the dietary valine requirement by PPval and PAval could be 1.44 and 1.50% in rainbow trout, respectively. These results supported that the estimated dietary valine requirement by PP(val.) and PA(val.) could be in close agreement with the values obtained from the previous conventional feeding method. Thus, the use of PFAA concentrations for determining essential amino acid requirements could be possible in rainbow trout with dorsal aorta cannulation.

• YAKHAK HOEJI
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• v.30 no.1
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• pp.47-50
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• 1986

The enantiomers of five amino acids (alanine, valine, threonine, leucine and phenylalanine) could be separated by gas chromatography with optically active (S)-5-isopropyll-$N^3$-phenyl-2-thiohydantoinic stationary phase, which prepared from L-valine and phenylisothiocyanate. Gas chromatographic separations on methylesterificated and N-trifluoroacetylated amino acids have been conducted in isothermal at several column temperatures (180~190, 200, $210^{\circ}C$). The separation factors were 1.29 (alanine, $190^{\circ}C$), 1.35 (valine, $190^{\circ}C$), 1.33 (threonine, $190^{\circ}C$), 1.17 (leucine, $190^{\circ}C$) and 1.05 (phenylalanine, $190^{\circ}C$) and D-isomers eluted prior to L-isomers in every instance. The result of this experiment shows that this stationary phase can be used for the separation of the other amino acids enantiomers.

• Microbiology and Biotechnology Letters
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• v.37 no.2
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• pp.140-146
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• 2009

Cyclosporin, an immunosuppressant, is a representative group of biologically active secondary metabolites produced by the fungus Tolypocladium inflatum. The amount and ratio of cyclosporin derivatives in the culture broth are an important factors for the production of cyclosporin A and the purification in the industrial process. Therefore, we studied the effect of amino acids and complex organic nitrogen sources using Tolypocladium inflatum mutants on the productivity of cyclosporin A and the ratio of cyclosporin derivatives. Overproducing mutant YHC-004 having seven times higher productivity than mother strain's could be obtained through the artificial mutation by UV irradiation. The concentration and kind of organic nitrogens and amino acids shows the profound effect on the productivity of cyclosporin A and ratio of cyclosporin derivatives. As a result, it was possible to raise the productivity and the ratio of cyclosporin A up to 3,430 mg/L and 93% respectively, but on the other hand the other cyclosporin derivatives decreased less than 2% in the culture broth.

• YAKHAK HOEJI
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• v.27 no.3
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• pp.185-205
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• 1983

Penicillins and cephalosporins are biosynthesized from L-.alpha.-aminoadipic acid, L-cysteine and L-valine. A tripeptide, LLD-$\delta$-($\alpha$-aminoadipyl)cysteinylvaline(LLD-ACV) was isolated from fermentation broths of Cephalosporium acremonium as well as of Penicillium chrysogenum and it was proved that the LL-$\delta$-($\alpha$-aminoadipyl cysteine was formed first in mycelia, to which valine would be connected to give LLD-ACV. However, several points are still unsolved; first, what mechanism is involved in the configurational change from L-valine to D-valine, second, what kind of cyclization mechanism gives a $\betha$-lactam ring and a thiazolidine ring and third, what is the pathways for the ring expansion from penicillins to cephalosporins. At present, it seems clear that LLD-ACV is cyclized to give isopenicillin N, which is transformed to penicillin N and further to cepbalosporin C. Other hydrophobic penicillins, including benzyl penicillin and penicillin V, are formed from isopenicillin N by acyl-exchange reactions catalyzed by penicillin transferase, rather than by acylation reaction on 6-aminopenicillanic acid(6-APA), which was isolated from the fermentation broth of P. chrysogenum and which would be formed by hydrolysis of $\delta-(\alpha$-amincadipyl)amido moiety at the C-6 position in isopenicillin N or penicillin N by penicillin acylase. Acylation of 6-APA is catalyzed also by penicillin acylase, but the reaction is proved not to be involved in penicillin biosynthesis. Understanding the biosynthesis of penicillins and cephalsoporins would provide solutions to increase in fermentation yields of penicillins, especially of cephalosporins and a solution to biological production of 7-aminocepbalosporanic acid (7-ACA) which is of importance in pharmaceutical industry. Still regulation mechanisms in penicillin and cephalosporin biosynthesis are unveiled at all.