• Archives of Pharmacal Research
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• 제18권6호
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• pp.371-375
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• 1995

Erythropoietin (EPO), a glycoprotein hormone, regulates the proliferation and differentiation of ereythroid progenitor cells. Many attempts have been made to identify the functionally important amino acids of the hormone. One of those early studies has found that heavy redioiodination of EPO caused the loss of its biological activity, suggesting some important role of one of the four tyrosine residues (Goldwasser, 1981). Thus, in this study, we have generated and tested four $Tyr{\dashrightarrow}Phe$ substitution mutants to clarify the possible role of the tyrosine residue(s) in the hormone's Tyrosine residue(s) in the hormone's biological activity. When the mutant and wild type EPO cDBAs were transfected into COS-7 cells and the biological activities of the muteins were assayed using the primary murine erythroid spleen cells, no mutation tested was found to affect the biological activity of the hormone. Thus we conclude that, contrary to the previous observation, none of the four tyrosine in eryghropoietin is critically involved in the binding of the hormone to its receptor.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.169-173
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• 1997

The behavior of tyrosine(Tyr.) residue of Bombyx mori silk fiber from yellow fluorescent cocoon has been examined for the dependence of pH in aqueous silk solution under the presence of orange II salt. Through the peak separation of angular dependence of spectral pattern of 15N-Tyr. and [1-13C]-Tyr. between the fiber axis and the molecular bond direction, N-H bond in fiber as well as the orientation distribution around the fiber axis were analyzed. Also, and sericin component was obtained from these angular dependence of oriented spectral pattern. The pH dependence of the 13C NMR chemical shift of B. mori silk fibroin was examined in aqueous solution in the presince of orange II are broad at pH$\geq$7.0. However, these become sharper at pH$\geq$8.0 and remain sharp at higher pH. In these higher pH range, a chemical shift change occurs due to the deprotonation of the Tyr. side group of fibroin. At higher pH. such a hydrophobic cluster is destroyed because of the electrostatic interaction according to the deprotonation of the Tyr-OH group.

• 분석과학
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• 제10권5호
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• pp.378-385
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• 1997

본 실험은 human glutathione S-transferase P1-1의 tyrosine 7 잔기에 대한 변이체를 작성하고, 기질특이성과 저해제의 효과를 조사하여, 이 잔기의 기능을 분석한 것이다. 1,2-dichloro-4-nitrobenzene과 1,2-epoxy-3-(p-nitrophenoxy)propane에 대한 GSH 포합반응에 대한 활성은 야생형에 비해 변이체 Y7F에서는 3~5%로 크게 저하하였으며, 효소에 결합한 GSH의 thiol기의 pKa는 2.4 pK 높았다. 저해제 hematin에 대한 $I^{50}$값은 야생형과 변이체 Y7F에서 비슷하게 나타났으며, 저해제 benastatin A와 S-(2,4-dinitrophenyl) glutathione에 대한 $I^{50}$값들은 다소 감소하였다. 이러한 결과들로부터 tyrosine 7 잔기는 기질의 결합에 관여하기보다 GSH-chloronitrobenzene 유도체와 GSH-epoxide 포함반응에 대한 촉매활성에 중요하다고 생각된다.

• Preventive Nutrition and Food Science
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• 제7권4호
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• pp.397-404
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• 2002

Soybean curd residue (SCR) was fermented by lactic acid bacteria, Lactobacillus rhamnosus LS and Entercoccus faecium LL, isolated from SCR. The pH, titratable acidify and viable cell counts were determined from the fermented SCR to evaluate the lactic acid production and growth of lactic acid bacteria. Optimal amounts of pretense enzyme and glucose, and ideal fermentation time for SCR fermentation were estimated by response surface methodology (RSM). Raw SCR fermented by indigenous microorganisms had 0.78 % titratable acidity, The acid production in SCR fermented by L. rhamnosus LS was greatly enhanced by the addition of glucose and lactose. However only glucose increased acid production by Ent. faecium LL. The proof test of SCR fermentation demonstrated that similar results for titratable acidity, tyrosine content and viable cell counts to that predicted could be obtained by the at optimized fermentation conditions. In the presence of 0.029 % (w/w) pretense enzyme and 0.9% (w/w) glucose, the SCR fermented by Ent. faecium LL showed 1.07% (w/v) of titratable acidity, 1.02 mg% tyrosine content and 2$\times$10$^{9}$ (cfu/g) of viable cell counts. With the SCR fortified with 0.033% pretense enzyme and 1.7% glucose, L. rhamnosus LS showed 1.8% (w/v) of titratable acidity, 0.92 mg% of tyrosine content and 2$\times$10$^{9}$ (cfu/g) of viable cell counts.

• Asian Pacific Journal of Cancer Prevention
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• 제14권7호
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• pp.4279-4282
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• 2013

Background: The activation and inactivation of receptor tyrosine kinases are tightly regulated to ensure faithful replication of cells. After having transduced extracellular growth activating signals, activated EGFR is subjected to downregulation either by clathrin mediated endocytosis or c-Cbl mediated proteasome degradation depending on the ligand concentration. c-Cbl is an ubiquitin ligase which requires a phosphorylated tyrosine residue at position 1045 in the cytoplasmic domain of EGFR to interact and add ubiquitin molecules. While activating mutations in exons 19 and 21 have been associated with the development of several cancers, the status of mutations at tyrosine 1045 coding exon 27 of EGFR remain to be investigated. Consistently, defective phosphorylation at 1045 has been associated with sustained phosphorylation of EGFR in non-small lung carcinomas. Hence in the present study we investigated the genetic status of the tyrosine 1045 coding site within exon 27 of EGFR gene to explore for possible occurrence of mutations in this region, especially since no studies have addressed this issue so far. Materials and Methods: Tumor chromosomal DNA isolated from thirty five surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking the tyrosine 1045 coding exon 27 of EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status. Results: Sequence analysis identified no mutations in the tyrosine 1045 codon of EGFR in any of the thirty five samples that were analyzed. Conclusions: The lack of identification of mutation in the tyrosine 1045 codon of EGFR suggests that mutations in this region may be relatively rare in oral squamous cell carcinomas. To the best of our knowledge, this study is the first to have explored the genetic status of exon 27 of EGFR in oral squamous cell carcinoma tissue samples.

• BMB Reports
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• 제31권2호
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• pp.135-138
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• 1998

A previous study on a yeast protein tyrosine phosphatase, YPTP1, using synthetic phosphotyrosine-containing peptides with various sequences as substrates revealed that DADEpYDA exhibits high affinity ($K_m=4{\mu}M$) toward the enzyme. A modified version of this peptide, GDADEpmFDA, immobilized on a resin, was used in this study as an affinity ligand for the purification of YPTP1. Phosphonomethyl-phenylalanine (pmF) was used as a nonhydrolyzable analog of the phosphotyrosine (pY) residue, with properties similar to pY. A protected form of pmF, $Fmoc-pmF(^{t}Bu)_{2}-OH$, was chemically synthesized and introduced during solid-phase peptide sythesis. YPTP1 was onrexpressed in an E. coli strain carrying a plasmid pT7-7-ptpl. Affinity chromatography of the crude lysate afforded PTPI (39 kDa) of about 50% purity.

• Bulletin of the Korean Chemical Society
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• 제31권9호
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• pp.2649-2655
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• 2010

$PKC{\delta}$-catalytic V5 Heptapeptide (FEQFLDI, FP7) interacts with heat shock protein 27 (HSP27) and inhibits HSP27-mediated resistance to cell death against various stimuli including radiation therapy. Here, we prepared radio-iodinated heptapeptide and further investigated its uptake properties in HSP27 expression cells. Peptide sequence of FP7 and a negative control peptide (WSLLEKR, QP7) was modified by substituting their C-terminus residue to tyrosine (FP6Y and QP6Y) to label radio-iodine. Iodinated peptides were confirmed by LC mass analysis with cold iodine reaction mixture. Accumulation of [$^{125}I$]iodo-FP6Y and [$^{125}I$]iodo-QP6Y in NCI-H1299 cell line, with higher level of HSP27, and NCI-H460 cell line, with lower level of HSP27, was measured by NaI(Tl) scintillation counter. The modification of substituting C-terminus residue of FP7 to tyrosine (FP6Y) did not affect its interaction with HSP27. Accumulation of [$^{125}I$]iodo-FP6Y in NCI-H1299 cells was 3 fold higher than in NCI-H460 cells. The novel radio-iodinated FP6Y would be used as a tracer for targeting HSP27 protein.

• Preventive Nutrition and Food Science
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• 제9권2호
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• pp.138-143
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• 2004

Soybean curd residues (SCR) obtained from hot and cold manufacturing processes were fermented by indigenous microorganisms, Lactobacillus rhamnosus LS and Bacillus firmus NA-l for 15 h at 37$^{\circ}C$. The pH, acidity, viable cell counts, and tyrosine content were evaluated in samples with variations in sugar, starter and type of SCR. The raw Doowon SCR (D-SCR, cold-processed) fermented by indigenous microorganism had a 0.9% acidity and 6.7 ${\times}$ 10$^{7}$ CFU/g viable cell counts, compared with the 0.11 % acidity and 6.7 ${\times}$ 10$^{6}$ CFU/g viable cell counts of raw fermented Pulmuwon SCR (P-SCR, hot-processed). After fermentation of raw P-SCR with 1 % glucose and 1 % L. rhamnosus LS starter, the viable cell counts, tyrosine content and acidity were 4.7 ${\times}$ 10$^{8}$ CFU/g, 16.3 mg% and 0.9%, respectively. In addition, the raw P-SCR fermented with Bacillus firmus NA-l as co-starter had a 0.45% acidity, 2.4 ${\times}$ 10$^{8}$ CFU/g lactic acid bacteria, and 3.3 ${\times}$ 10$^{6}$ CFU/g Bacillus sp. In particular, the tyrosine content was increased 5 fold. The drying of fermented SCR was completed by hot-air drying (5$0^{\circ}C$) within 12 h; the dried P-SCR and D-SCR had 1.8 ${\times}$ 10$^{7}$ CFU/g and 5.3 ${\times}$ 10$^{6}$ CFU/g viable cell counts, respectively. The concentrate of methanol extract from fermented D-SCR inhibited the initial cell growth of E. coli, Staphylococcus aureus and Pseudomonas aeruginosa in liquid culture.

• 한국식품영양과학회지
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• 제35권1호
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• pp.115-120
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• 2006

일본 청국장에서 분리된 Bacillus firmus NA-1과 재래청국장에서 분리 한 Bacillus subtilis GT-D를 이용하여 전지활성 생 대두미세분말(MFS)첨가 및 발효시간에 따른 비지 발효물의 혈전용해효소, 가수분해효소, 점질물, 펩타이드 생산 및 풍미개선 효과를 알아보았다. $84\%$의 수분함량을 포함하는 비지에 대두미세분말을 10, 15, $20\%$ 첨가함으로써 78, 74, $70\%$로 수분함량을 감소시킬 수 있으며, 발효시간이 경과할수록 tyrosine함량이 증가하였으며, B. firmus NA-1 균주보다는 B. subtilis GT-D 균주를 사용하는 경우에 높은 값을 보였다. 발효비지의 점조도는 B. firmus NA-1 균주를 이용한 발효물이 높은 값을 보였으며, 두 균주 모두 MFS $20\%$를 첨가한 후 26시간 발효한 발효물에서 2.18, $0.35\;Pa{\cdot}s^n$로 가장 높은 점조도 값을 나타내었다. 혈전용해효소 역시 B. firmus NA-1 균주를 이용한 비지 청국장에서 $10\%$ 이상의 높은 활성을 보였으며, 발효 22시간까지 증가하다가 26시간 부터는 큰 변화가 없거나 감소하는 경향을 보였다. 따라서 $20\%$의 MFS를 첨가한 후 $42^{\circ}C$에서 22시간 동안 발효하는 것이 발효취 생성을 최소화하는 조건이라 사료되었다. 비지청국장의 동결건조는 청국장 냄새 및 수분함량을 $6\%$ 수준으로 줄일 수 있었으며, 혈전용해효소의 활성을 포함하였다. B. firmus NA-1 균주를 이용한 시료에서는 615 unit/g의 가장 높은 protease의 활성을 보였으며, B. subtilis GT-D 균주를 이용한 시료에서는 $1903\;mg\%$의 tyrosine 함량 및 180 unit/g의 a-amylase의 활성을 나타내었다.

• Archives of Pharmacal Research
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• 제22권5호
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• pp.464-473
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• 1999

Regulation of phosphcholine-hydrolyzing phosphatase (phosphocholine-phosphatase) activity, purified from bovine brain, was examined under physiological conditions. Various endogenous phosphomonoesters, which were utilized as substrate, inhibited the phosphocoline-phosphatase activity competitively (Ki 5.5-$82.0 {\mu}M$); among phosphomonoesters tested, there was a similar order of capability between the binding affinity of substrate and the inhibitory potency. In addition, phosphate ions also inhibited the phosphatase activity competitively with a Ki value of approximately $16{\mu}M$. Although leucine or theophylline inhibited the phosphatase activity at pH 9.0, their inhibitory action decreased greatly at pH 7.4. The pH-Km and pH-Vm profiles indicate that ionizable amino acids are involved in substrate binding as well as catalysis, alluding that the phosphatase activity may be highly dependent on the intracellular pH. Amino acid modification study supports the existence of tyrosine, arginine or lysine residue in the active site, and the participation of tyrosine residue in the catalytic action may e suggested positively for the susceptibility to the action of tetranitromethane or HOl-generator. Separately, the oxidative inactivation of phosphocholine-phosphatase activity was investigated. Of oxidants tested, HOONO, HOCl, HOl and $ascorbate/Cu^{2+}$ system were effective to inactivate the phosphatase activity. Noteworthy, a remarkable inativation was accomplished by $30{\mu}M$ HOCl in combination with 1 mM Kl. Inaddition, $Cu^{2+}(3{\mu}M) $in combination with ascorbate at concentrations as low as 0.1-0.3 mM reduced the phosphatase activity to a great extent. From these results, it is proposed that the phosphocholine-phosphatase activity may be regulated endogenously and susceptible to the various oxidant system in vivo.