• Journal of Life Science
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• v.12 no.4
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• pp.464-468
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• 2002

Enzymatic activities and fluorescence spectroscopic properties of the double mutant proteins P96L/F139W, P96L/F258W and a triple mutant protein P96L/F139W/F258W of tryptophan synthase $\alpha$ subunit from Escherichia coli was examined to study tertiary and local structure changes around the tryptophan residues. The enzymatic activities of P96l./F139W and P96L/F258W were similar, but P96L/F139W/F258W had lower activity, as compared to wild type. The fluorescence intensities of double mutant, P96L/F139W and P96L/F258W, were decreased but that of a triple mutant, P96L/F139W/F258W, was increased when compared to wild type. The sum of the maximum fluorescence intensity (fluorescence intensity at the λ$_{max}$) for the double mutant proteins was not equal to the intensity seen in the triple mutant protein. The enzymatic activity and fluorescence data indicate that the replacement of Pro$^{96}$ longrightarrowLeu might affect on the stability of helix 8 and the loop located between strand 4 and helix4. The result suggests that the tertiary structure of triple mutant (P96L/F139W/F258W), being different from wild type, might have more compact residual structure at the vicinity of 139 and 258.8.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.1
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• pp.67-73
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• 2012

In the present study, we investigated the effects of dipeptides on melanogenesis in B16 melanoma cells. It was found that WV (Trp+Val), WM (Trp+Met), and CQ (Cys+Gln) decreased melanin production dosedependently. However, dipeptides did not directly inhibit tyrosinase activity, the rate-limiting melanogenic enzyme. Therefore, we further investigated the expression of tyrosinase. Our results showed that ${\alpha}$-MSH-induced tyrosinase expression was down-regulated by WV, WM, and CQ. Thus, we propose that WV, WM, and CQ show hypopigmentary activity through tyrosinase down-regulation.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.135-153
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• 2015

The aromatic amino acids, which are composed of $\small{L}$-phenylalanine, $\small{L}$-tyrosine and $\small{L}$-tryptophan, are general components of protein synthesis as well as precursors for a wide range of secondary metabolites. These aromatic amino acids-derived compounds play important roles as ingredients of diverse phenolics including pigments and cell walls, and hormones like auxin and salicylic acid in plants. Moreover, they also serve as the natural products of alkaloids and glucosinolates, which have a high potential to promote human health and nutrition. The biosynthetic pathways of aromatic amino acids share a chorismate, the common intermediate, which is originated from shikimate pathway. Then, tryptophan is synthesized via anthranilate and the other phenylalanine and tyrosine are synthesized via prephenate, as intermediates. This review reports recent studies about all the enzymatic steps involved in aromatic amino acid biosynthetic pathways and their gene regulation on transcriptional/post-transcriptional levels. Furthermore, results of metabolic engineering are introduced as efforts to improve the production of the aromatic amino acids-derived secondary metabolites in plants.

• Korean Journal of Poultry Science
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• v.45 no.2
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• pp.73-79
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• 2018

The objective of this study was to calculate the unit price of an alternative feed ingredient for broiler chickens in consideration of the energy and nutritive contents in the feed ingredient by using a simple Excel worksheet. A corn-distiller's dried grains with solubles (corn-DDGS) was used as an alternative ingredient and corn and soybean meal as ingredients to be replaced. The net change of feed price was calculated based on the replacement values which were estimated in consideration of energy and nutrient concentration in feed ingredients used in the calculation, the price of feed ingredients and inclusion rate of the alternative ingredient. The nitrogen corrected apparent metabolizable energy(AMEn) and standardized ileal digestible AA including Lys, Met, Thr, and Trp, total Ca, and available P were employed as nutritive component to calculate the replacement values for individual feed ingredients. The equation for replacement was 1 ${\times}$ corn-DDGS + 0.0334 ${\times}$ soybean oil + 0.0182 ${\times}$ Limestone = 0.8893 ${\times}$ corn + 0.13 ${\times}$ soybean meal + 0.0004 ${\times}$ Lys + 0.0022 ${\times}$ Met + 0.0005 ${\times}$ Trp + 0.0028 ${\times}$ Thr + 0.0264 ${\times}$ dicalcium phosphate. The replacement price of corn-DDGS was calculated to be 270 won/kg when the inclusion rate was 15% and the energy and nutrient contents were considered in the calculation. In conclusion, the Excel-based ingredient price calculator may be useful to determine the economic value when an alternative feed ingredient is used in diets fed to broiler chickens.

• Korean Journal of Food Science and Technology
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• v.48 no.6
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• pp.610-617
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• 2016

Melatonin, known as a powerful wide-spectrum antioxidant, is consumed as a food supplement in some countries, but its applicability as an antioxidant additive was not yet studied. Therefore, we evaluated the antioxidant activity of melatonin by DPPH, ABTS, FRAP and ORAC assays as well as its ability to inhibit perilla oil oxidation. The activities of four other related indoles were also compared. Melatonin showed the highest antioxidant activity (mmol trolox equivalent per mol indole, mmol TE) in ORAC (2,159) assay, but a low antioxidant activity in DPPH (0.63), ABTS (91), and FRAP (764) assays, whereas serotonin showed an opposite result. Addition of 1% (w/w) melatonin to perilla oil extended the induction period of oxidation up to about 2 times ($2.93{\pm}0.47h$) compared to that of control ($1.43{\pm}0.26h$) in the Rancimat assay, corresponding to almost 50% of the ability of butylated hydroxyl toluene (BHT). Tryptamine was the most effective indole that inhibited perilla oil oxidation ($9.53{\pm}1.43h$).

• Journal of Life Science
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• v.22 no.8
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• pp.1046-1051
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• 2012

In order to investigate the changes in bioactive materials induced in goldfish brains by $^{18}F$ irradiation, the variations in the neurotransmitter levels in the whole brain were studied. The distance between the goldfish and 580 mCi of $^{18}F$ was about 4 cm, and the exposure lasted for 4 hrs. The absorption level calculated based on the distance, exposure time, and half-life of $^{18}F$ was approximately 2 Gy. After sacrifice by $^{18}F$ irradiation or untreated conditions, ten brains were dissected or immediately frozen, respectively. The tissues were extracted in acetic acid. After lyophilization, the samples were dissolved in distilled water and were further purified on a reverse-phase HPLC column. There were no differences in the intensities of the bioactive materials between $^{18}F$-exposed goldfish and control goldfish, while the only peak corresponded to 13 min, which indicated a significant increase in the irradiated brains. Our analysis has found that this compound is tryptophan. This result suggests that $^{18}F$ leads to changes in a classical neurotransmitter, tryptophan, in both the brains of control goldfish and goldfish contaminated by irradiation.

• Journal of Life Science
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• v.32 no.9
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• pp.729-733
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• 2022

Aggregation of normally soluble proteins can cause disease-related problems. Tryptophan synthase α-subunit (αTS) in E. coli adopts one of most popular structural scaffolds, the TIM barrel fold. Previous mutagenesis of the αTS gene resulted in many aggregation-prone mutant proteins. Here, Y173F (Tyr at residue 173 to Phe) substitution, which imparts increased stability, was tested for its ability to suppress aggregation of aggregation-prone mutant proteins (Y4C, S33L, P28L, P28S, G44S, D46N, P96L, and P96S). Aggregation was suppressed in all eight severe aggregate-forming mutants (all differing in their mutation positions), by the Y173F replacement. P28L αTS, which was available in pure form, was further analyzed and showed reduced secondary structure content, lower stability, and a looser structure with more exposed hydrophobic surface compared to the wild type protein. A double mutant P28L/Y173F protein showed almost no indication of these changes compared to the wild type protein. We hypothesized that Tyr at position 173 in αTS is positioned at the hydrophobic core and may serve to suppress the aggregation of this protein caused by other residues. Important residue (s) could be working widely in the prevention/suppression of protein aggregation.

• KSBB Journal
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• v.21 no.5
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• pp.401-404
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• 2006

Macroporous Poly(Methacrylic acid-co-Ethylene Glycol Dimethacrylate) Rods were in situ thermal initialized within a empty column($3.9{\times}150mm$) by free radical polymerization. The polymerization mixture was consisted of monomer, cross-linking monomer, porogenic solvent, initiator and control the ratio of these materials, column efficiency could be developed. Caffeine and tryptophan as separation substances and the retention mechanism of this kind of monolithic column was mainly hydrogen bond function.

• Journal of Food Hygiene and Safety
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• v.14 no.3
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• pp.259-264
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• 1999

To evaluate the bacterial reverse mutation of xylooligosaccharide(XO)s the in vitro Ames test using Salmonella typhimurium (TA9S, TAIOO, TA1535, TA1537) and Escherichia coli (WP2 uvrA) was performed. XO was negative in Ames test with Salmonella typhimurium and Escherichia coli with and without rat liver microsomal enzyme (S-9 fraction). According to the results, XO does not cause bacterial reverse mutation.

• Korean Journal of Microbiology
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• v.25 no.1
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• pp.46-51
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• 1987

In order to increase the production of tryptophan by maximizing expression of recombinant trp plasmid, Klebsiella pneumoniae KC 105(pheA tyrA trpE trpR tyrR) was genetically modified. KC 107, inosine monophospate(IMP) auxotroph from KC 105 and KC 108, histidine(His) auxotroph from KC 107 were also derived respectively to increase phosphoribosylpyrophosphate(PRPP) production which is required for tryptophan biosynthesis. From KC 107 phosphoribosylpyrophosphate consumption which is required for tryptophan biosynthesis. From KC 107 and KC 108, KC 109 and KC 110, both arginine auxotrophs were derived respectively. To investigate the expression of recombinant trp plasmid in the selected K. pneumoniae mutants, the auxotrophic mutants were transformed with recombinant trp plasmids pSC 101-$trpE^{FBR}$, pSC 101-trpL(.DELTA.att) $trpE^{FBR}$ (pSC 101-trp-AF). Amount of tryptophan produced and activities of tryptophan synthase of $trpR^{-}$ mutant (KC 100) and $tyrR^{-}$ mutnat(KC 105) containing recombinant plasmid pSC 101-trp operon were increased by 30-40% as compared with KC 99(pheA tyrA trpE) containing recombinant plasmid pSC 101-trp operon. Activities of tryptophan synthase and production of tryptophan of KC 108 ($His^{-}$) and KC 109($Arg^{-}$) containing recombinant plasmid pSC 101-trp operon were increase by two-fold as compared with KC 107 containing pSC 101-trp operon.