• Korean Journal of Microbiology
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• v.29 no.5
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• pp.278-283
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• 1991

Two amino acid residues ($Ala^{494}$ and $Ser^{495}$ of E. coli .gamma.-glutamylcysteine synthetase have been investigated whether they are the site of feedback inhibition by site specific mutagenesis. Single substitution of $serine^{495}$ (S495F), and double substitutions of alanine$^{494}$ and $serine^{495}$ (A494G-S495F) resulted in the inactivation of the .gamma.-glutamylcysteine synthetase activity. Substitution of $alanine^{494}$ with $glycine^{494}$ resulted in a higher level of feedback inhibition. These results suggest that $serine^{495}$ in .gamma.-glutamylcysteine synthetase is required for its catalytic acitvity and $alanine^{494}$ is presumably related to the feeback inhibition site.

• Bulletin of Food Technology
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• v.17 no.4
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• pp.98-106
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• 2004

Two mutant enzymes of $\gamma$-glutamylcysteine synthetase ($\gamma$-GCS) which catalyzed the synthesis of $\gamma$-glutamylcysteine from L-glutamic acid and L-cysteine in the presence of ATP, were prepared bypoint mutation of $\gamma$-GCS gene with site-directed mutagensis in E. coli. Conformational structuresand catalytic reaction kinetics of mutant enzymes were compared with wild type $\gamma$-GCS afterpurification. The S495F mutant enzyme (serine at 495 residue was substituted with phenylalanine),which had no catalytic activity for $\gamma$-glutamylcysteine synthesis, rarely folded even in neutral pH.However, the mutant A494V (alanine of 494 residue was replaced by valnine) which showed 50 %increase of activity, had a high folding structure. The folding structure of A494V also more stable athigh temperature and extreme pH compared to wild type and S495F. Reaction kinetics of wild typeand A494V were also investigated, Km value of A494V was smaller than that of wild type, while itshowed a little difference at Vmax values. This result evolved that alanine at 494 may be involved inbinding site of substrate rather than catalytic site. In addition, change of catalytic activity by onepoint mutation was highly correlated with the folding structure of enzyme.

• 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.

• Archives of Pharmacal Research
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• v.21 no.5
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• pp.487-495
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• 1998

Gorwth factors such as TGF-beta, PDGF and FGF are thought to play important roles in wound healing. However, thier biological activity and signal transduction during wound repair remain poorly understood. Growth factors are often ligands for receptor tyrosine kinase and receptor serine/threonine kinases. With recent advances in signal transduction by receptor kinases, we are beginning to understand the underlying mechanism of how growth factors may regulate cutaneous wound repair. In this paper, we will describe the pharmacological effects of growth factors on wound healing, and dscuss the potential underlying signaing mechanisms. thus, we hope to provide the basis for designing more specific therapeutics for wound healing in the near future.

• Food Science and Preservation
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• v.6 no.4
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• pp.495-499
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• 1999

The free sugars in leaf and root of dandelion were composed of sucrose, glucose and fructose. The contents of total free sugars was higher in root than those in leaf. The oxalic acid, citric acid and malic acid contents of leaf was 45.4, 3.6, 2.7mg/100g-f.w., respectively. And the oxalic acid, citric acid and malic acid contents of root was 34.6, 2.1, 1.6mg/100g-f.w., respectively. Total free organic acid content of leaf was higher than that of root. The major free amino acids of dandelion were aspartic acid, serine, asparagine, glutamic acid, glycine, valine, isoleucine and content of glutamic acid was highest in free amino acids. The contents of vitamin A in leaf and root of dandelion was 135.4 and 34.1$\mu\textrm{g}$/100g-f.w., respectively. The contents of vitamin C in leaf and root of dandelion was 67.4 and 4.6 mg/100g-f.w., respectively.

• Journal of Life Science
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• v.5 no.4
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• pp.170-180
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• 1995

A carotennnoprotein from the skin of Ascidian(Halocynthia roretzi) was extracted by Triton X-100 and purified by ammonium sulfate fraction, SephadexG-200 charomatography and DEAE-cellulose ion exchange chromatography. The carotenoprotein was redwith broad $\lambda$$_{max}$ between 495, 467 and 318nm. The red carotenoprotein had an approximate molecular weight of 326KDa(gel filtration). SDS-PAGE indicated the presence of two polypeptodes of 84.1KDa and 74.4KDa, with different mobility in polyacrylamide gel electrophoresis. In the presence of denaturing agents such as organic solvent aand extreme pH, the red complex readily disociates to liberate the yellow carotenoid($\lambda$$_{max}$ 452nm) and a colourless apoprotein. The amino acid composition of carotenoprotein were mainly threonine(15.2%), aspartic acid(12.2%), glutamic acid(11.9%) and serine(9.6%), while proline was not found. The carotenoprotein consisted of lipids as structure units. Its major fatty acids composion were C$_{18:1}$, C$_{16:1}$, and C$_{16:0}$. The monounsaturated fatty acids(41.5%) contained abundant content compared to other fatty aacids(polyunsaturated fatty acids 37.4%, saturated fatty acids 20.6%).

• KSBB Journal
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• v.18 no.6
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• pp.495-499
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• 2003

The effect of operating parameters (reaction temperature and time) and reaction modes (batch and semi-batch) on the behavior of amino acid production from hydrothermal decomposition of fish-derived wastes was investigated. The amino acids obtained in batch experiments at temperature of 250$^{\circ}C$ were mainly alanine (Ala) and glycine (Gly) at maximum yield of 65 and 28mg/g-dry fish, respectively. At relatively lower temperature of 200$^{\circ}C$, the yield of high-molecular-weight amino acids such as aspartic acid (Asp) and serine (Ser) is high, but decreases as temperature increases. It is likely that high-molecular-weight amino acids decompose faster than low-molecular ones. Semi-batch mode of reaction suppressed decomposition of amino acids into organic acids (or volatile materials) by continuously removing the products from the reaction zone as soon as they are formed. Thus, large amount of high-molecular-weight amino acids such as Asp and Ser at this reaction mode was observed.