• Microbiology and Biotechnology Letters
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• v.16 no.5
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• pp.407-412
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• 1988

In order to increase the tryptophan productivity of E. coli SB1007, a mutant resistant to sulfanilamide was isolated and then a tyrosine auxotroph TY-90 was derived from the sulfanilamide-resistant mutant SA3-39-16. In the test-tube culture a quantitative amount of tryptophan was accumulated in strain TY-90 but in a jar fermentor culture the productivity was lower as compared to the level obtained by the parent strain. From the double auxotrophic mutant SB2756, a revertant resistant to 2, 000$\mu\textrm{g}$/$m\ell$ of $\beta$-thienylalanine, TA 40-10, was selected and then phenylalanine auxotrophs were derived from the revertant strain TA-40-10. One of the phenylalanine auxotrophs, TP-4, accumulated 3.7g/$\ell$ of L-tryptophan after 71-hr cultivation in a jar fermentor experiment.

• Journal of Life Science
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• v.15 no.4 s.71
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• pp.633-640
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• 2005

The purified xylanase from Bacillus pumilus TX703 was modified with various chemical modifiers to determine the active sites of the enzyme. Treatment of the enzyme with group-specific reagents such as carbodiimide or N-bromosuccinimide resulted in complete loss of enzyme activity. These results assumed that these reagents reacted with glutamic acid or aspartic acid and tryptophan residues located at or near the active site. In each case, inactivation was performed by pseudo first-order kinetics. Inhibition of enzyme activity by carbodiimide and W-bromosuccinimide showed non-competitive and competitive inhibition type, respectively. Addition of xylan to the enzyme solution containing N-bromosuccinimide prevented the inactivation, indicating the presence of tryptophan at the substrate binding site. Analysis of kinetics for inactivation showed that the loss of enzyme activity was due to modification of two glutamic acid or aspartic acid residues and single tryptophan residue.

• Journal of Plant Biotechnology
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• v.42 no.3
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• pp.186-195
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• 2015

Anthranilate synthase (AS) is a key enzyme in the biosynthesis of tryptophan (Trp), which is the precursor of bioactive metabolites like indole-3-acetic acid and other indole alkaloids. Alpha anthranilate synthase 2 (OsASA2) plays a critical role in the feedback inhibition of tryptophan biosynthesis. In this study, two vectors with single (F124V) and double (S126F/L530D) point mutations of the OsASA2 gene for feedback-insensitive ${\alpha}$ subunit of rice anthranilate synthase were constructed and transformed into wildtype Dongjinbyeo by Agrobacterium-mediated transformation. Transgenic single and double mutant lines were selected as a single copy using TaqMan PCR utilized nos gene probe. To select intergenic lines, the flanking sequence of RB or LB was digested with a BfaI enzyme. Four intergenic lines were selected using a flanking sequence tagged (FST) analysis. Expression in rice (Oryza sativa L.) of the transgenes resulted in the accumulation of tryptophan (Trp), indole-3-acetonitrile (IAN), and indole-3-acetic acid (IAA) in leaves and tryptophan content as a free amino acid in seeds also increased up to 30 times relative to the wildtype. Two homozygous event lines, S-TG1 and D-TG1, were selected for characterization of agronomic traits and metabolite profiling of seeds. Differentially expressed genes (DEGs), related to ion transfer and nutrient supply, were upregulated and DEGs related to co-enzymes that work as functional genes were down regulated. These results suggest that two homozygous event lines may prove effective for the breeding of crops with an increased level of free tryptophan content.

• Korean Journal of Poultry Science
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• v.17 no.4
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• pp.303-309
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• 1990

In order to study the effect of diet supplemented with 0.015% (150ppm) of L-tryptophan on the performance of broiler breeder, the performance of parent stock of 1768 breeder(Hubbard) fed on the diet supplemented with L tryptophan was compared with those of 1105 breeders fed on the basal (control) diet Henday egg and settable egg production, fertility, hatchability and number of quality chicks per settable egg were recorded during 133 days(34－52 week－old) of experimental feeding period. Also during 28 days of after experimental feeding period(53－56 week－old) the henday egg and settable egg production were recorded. The henday egg production of breeder fed L-tryptophan was similar with that fed the control diet during 7 weeks of the peak laying period(34－41 week－old) after beginning of the experimental feeding but which was significantly(P＜0.05) higher during 84 days of the post peak laying period(41－52 week－old) and 28 days of after experimental feeding period(53－56 week－old) than those of control And birds fed the L-tryptophan layed significantly (P＜0.01) higher numbers of the sellable eggs than those fed control diet during the post peak laying and after experimental feeding periods. While the coefficient of variance for the henday egg and settable egg production were shown lower values in birds fed the diet supplemented with L-tryptophan compared with those fed the control diet Also the diet containing L-tryptophan did not affect fertility and hatchability of settable egg though the number of quality chicks per sellable egg was higher significantly(P＜0.05) in birds fed the L-tryptophan than that fed the control diet.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.963-966
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• 2013

• Journal of the Korean Chemical Society
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• v.52 no.4
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• pp.350-355
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• 2008

• Bulletin of the Korean Chemical Society
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• v.29 no.9
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• pp.1823-1826
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• 2008

• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.453-459
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• 2006

D-tryptophan and N-CBZ-D-phenylalanine were separated using ionic liquid as additives for the mobile phase in high performance liquid chromatography (HPLC). The ionic liquid of 1-butyl-3- methylimidazolium tetrafluoroborate (${[BMIm]}^+{[BF_4]}^-$) was used. Mobile phases were 65％, 70％, and 80％ methanol in water with addition of different concentrations (0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, and 15.0 mmol/L) of the ionic liquid. The experiments were performed on stainless steel column, $3.9{\times}300mm$ i.d., packed with $15{\mu}m$ octadecyl-bonded silica gel at laboratory.The retention factor of D-tryptophan was not negligibly changed while that of N-CBZ-D-phenylalanine was decreased. The resolution between the two components were affected by the contents of methanol and ionic liquid in the mobile phase. With the small content of methanol and the high concentration of ionic liquid, the resolution was improved.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.828-832
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• 2012

We performed replica exchange molecular dynamics (REMD) simulations of the tripzip2 peptide (betahairpin) using the GB implicit and TI3P explicit solvation models. By comparing the resulting free energy surfaces of these two solvation model, we found that the GB solvation model produced a distorted free energy map, but the explicit solvation model yielded a reasonable free energy landscape with a precise location of the native structure in its global free energy minimum state. Our result showed that in particular, the GB solvation model failed to describe the tryptophan packing of trpzip2, leading to a distorted free energy landscape. When the GB solvation model is replaced with the explicit solvation model, the distortion of free energy shape disappears with the native-like structure in the lowest free energy minimum state and the experimentally observed tryptophan packing is precisely recovered. This finding indicates that the main source of this problem is due to artifact of the GB solvation model. Therefore, further efforts to refine this model are needed for better predictions of various aromatic side chain packing forms in proteins.

• BMB Reports
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• v.45 no.8
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• pp.452-457
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• 2012

Diketoreductase (DKR) from Acinetobacter baylyi contains two tryptophan residues at positions 149 and 222. Trp-149 and Trp-222 are located along the entry path of substrate into active site and at the dimer interface of DKR, respectively. Single and double substitutions of these positions were generated to probe the roles of tryptophan residues. After replacing Trp with Ala and Phe, biochemical and biophysical characteristics of the mutants were thoroughly investigated. Enzyme activity and substrate binding affinity of W149A and W149F were remarkably decreased, suggesting that Trp-149 regulates the position of substrate at the binding site. Meanwhile, enzyme activity of W222F was increased by 1.7-fold while W222A was completely inactive. In addition to lower thermostability of Trp-222 mutants, molecular modeling of the mutants revealed that Trp-222 is vital to protein folding and dimerization of the enzyme.