• 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.

• Preventive Nutrition and Food Science
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• 제15권2호
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• pp.98-104
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• 2010

The seeds from two mulberry fruits [Morus alba (MA) and Cudrania tricuspidata (CT)] were examined for their oil content, and fatty acid, phytosterol and tocopherol compositions and contents. Moreover, polyphenolic compounds and biological activity of the two defatted seed residue extracts were also evaluated. Oil contents of MA and CT seeds were 29.36% and 16.69%, respectively, while MeOH extracts of the defatted MA and CT seed residues were 5.10% and 6.22%, respectively. The two seed oils were composed of 81.4 and 74.37% linoleic, 5.75 and 11.39% oleic, 8.40 and 10.18% palmitic acid, and 3.52 and 3.0% stearic acids, and two other minor fatty acids, such as linolenic and arachidic acids. MA seed had higher contents of phytosterols (507.59 mg/100 g of oil), tocopherols (99.64 mg/100 g of oil), and total flavonoid (106.50 mg/100 g of seed) than CT seed, whereas CT seed had higher levels of total polyphenol than MA seed. The MeOH extract of MA seed residue showed higher antioxidant, anti-diabetic, and anti-melanogenic activity than that of CT seed residue. trans-Resveratrol (9.62 mg/100 g), quercetin (54.83 mg/100 g), and 4-prenylmoracin (48.70 mg/100 g), were found to be the main polyphenolic components in the MeOH extract of MA seed residue. These results indicate that MA seeds are good sources of essential dietary phytochemicals with antioxidant, anti-diabetic and anti-melanogenic activity.

• 한국잡초학회지
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• 제13권4호
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• pp.234-249
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• 1993

제초제(除草劑)는 현대(現代) 농업(農業)에서 필수적인 농자재(農資材)이나 생리활성(生理活性)을 갖기에 비목적대상생물(非目的對象生物)에 대한 위해성(危害性)을 배제(排除)할 수 없다. 제초제(除草劑)의 문제점(問題點)중 잔류문제(殘留問題)는 가장 중요한 부분이며 그중 인간생활(人間生活)과 밀접한 관계(關係)를 갖는 토양(土壤), 농작물(農作物)중의 잔류(殘留)는 더욱 중요하다. 토양(土壤)과 농작물(農作物)중 제초제(除草劑)의 잔류분해성(殘留分解性)은 토양(土壤), 기상(氣象), 제초제(除草劑)의 사용(使用) 및 작물재배(作物栽培) 등의 조건(條件)에 따라 현저히 변화(變化)되나, 현(現) 시점(時點)에서 토양(土壤) 중 제초제(除草劑)의 잔류(殘留)에 대한 문제점(問題點)은 후작물(後作物)에 대한 영향(影響)과 같은 국부(局部)적인 것을 제외(除外)하고는 거의 없으며 농작물(農作物)중 잔류(殘留) 또한 큰 문제(問題)가 없는 것으로 사료(思料)된다. 그러나 국민건강(國民健康), 토양생태계(土壤生態系)를 비롯 환경(環境)에 대한 더 높은 안정성(安定性) 확보(確保)를 위하여 제초제(除草劑)에 대한 모니터링실험과 같은 잔류성(殘留性) 조사(調査)가 더 많이 요구(要求)되며 사용자(使用者)는 안전사용기준(安全使用基準)을 준수(遵守)해야 하겠으며 제초제개발측면(除草劑開發側面)에서는 보다 저독성(低毒性) 약제(藥劑)를 개발(開發)하는데 최선(最善)을 다해야 하겠다.

• BMB Reports
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• 제32권4호
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• pp.326-330
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• 1999

An aspartase purified from Hafnia alvei was inactivated by diethylpyrocarbonate (DEP) in a pseudo-first-order inactivation. The first-order plot was biphasic. The inactivation process was not saturable and the second order rate constant was $1.3\;M^{-1}s^{-1}$. The inactivated aspartase was reactivated with NH₂OH. The difference absorption spectrum of DEP-inactivated vs native enzyme preparations revealed a marked peak around 242 nm. The pH dependence of the inactivation rate suggests that an amino acid residue having a pK value of 7.2 was involved in the inactivation. L-aspartate, fumarate (substrates), and chloride ion (inhibitor) protected the enzyme against inactivation, indicating that histidine residues for the enzyme activity are located at the active site of this aspartase. Inspection of the presence and absence of $Cl^-$ ion demonstrated that the number of essential histidine residues is less than two. Thus, one or two histidines are in or near the aspartate binding site and participate in an essential step of the catalytic reaction.

• 한국자기공명학회논문지
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• 제9권2호
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• pp.110-121
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• 2005

E.coli methionyl tRNA synthetase consist of 676 amino acids and plays a key role in initiation of protein synthesis. The native form of this enzyme is a homodimer, but the monomeric enzyme truncated approximately C-terminal 120 amino acids retains the full enzymatic activities. X-ray crystal structure of the active monomeric enzyme shows that it has two domains. The N-terminal domain is thought to be a binding site for acceptor stem of tRNA, ATP, and methionine. The C-terminal domain is mainly a-helical and makes an interaction with the anticodon of $tRNA^{Met}$. Especially it is suggested that the region of helix-loop-helix including the tryptophan residue at the position 461 may be the essential for the interaction with anticodon of $tRNA^{Met}$. In this work the structure and function of E. coli methionyl-tRNA synthetase was studied by spectroscopic method (NMR, CD, Fluorescence). The importance of tryptophan residue at the position 461 was investigated by fluorescence spectroscopy. Tryptophan 461 is expected to be an essential site for the interaction between E. coli methionyl-tRNA synthetase and E. coli $tRNA^{Met}$. Proton and heteonuclear 2-dimensional NMR spectroscopy were also used to elucidate the protein-tRNA interaction.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3405-3409
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• 2013

The activation of heat shock factor 1 (HSF1) can be induced by the changes in environmental pH, but the mechanism of HSF1 activation by acidification is not completely understood. This paper reports that a low pH (pH~6.0) can trigger human HSF1 activation. Considering the involvement of the imidazole group of histidine residues under acid pH stress, an in vitro EMSA experiment, Trp-fluorescence spectroscopy, and protein structural analysis showed that the residue, His83, is the essential for pH-dependent human HSF1-activation. To determine the roles of His83 in the HSF1-mediated stress response affecting the cellular acid resistance, mouse embryo fibroblasts with normal wild-type or mutant mouse HSF1 expression were preconditioned by heating or pH stress. The results suggest that His83 is essential for HSF1 activation or the HSF1-mediated transcription of heat shock proteins, in protecting cells from acid pH stress.

• BMB Reports
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• 제33권1호
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• pp.49-53
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• 2000

PMAP-23 is a 23-residue antimicrobial peptide derived from porcine myloid cells. In order to investigate the effects of two Pro residues at positions 12 and 15 of PMAP-23 on antibiotic activity, two analogues in which Ala was substituted for Pro residue at position 12 or 15 were synthesized. $Pro^{12}{\rightarrow}Ala$ (PMAPl) or $Pro^{15}{\rightarrow}Ala$(PMAP2) substitution in PMAP-23 caused a significant reduction on antitumor and phospholipid vesicle-disrupting activities, but did not cause a significant effect on antibacterial activity. PMAP-23 displayed the type I ${\beta}-turn$ structure with a negative ellipticity at near 205 om in SDS micelle, whereas PMAP1 and PMAP2 had a somewhat ${\alpha}-helical$ propensity in TFE solution, as compared to PMAP-23. These results suggest that two Pro residues of positions 12 and 15 in PMAP-23 play important roles in the formation of ${\beta}-turn$ structure on lipid membrane and its ${\beta}-turn$ structure may be essential for antibiotic activity including phospholipid vesicle-disrupting property.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2179-2183
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• 2016

Nitrilases pose attractive alternatives to the chemical hydrolysis of nitrile compounds. The activity of bacterial nitrilases towards substrate is intimately tied to the formation of large spiral-shaped oligomers. In the nitrilase CynD (cyanide dihydratase) from Bacillus pumilus, mutations in a predicted oligomeric surface region altered its oligomerization and reduced its activity. One mutant, CynD Y70C, retained uniform oligomer formation however it was inactive, unlike all other inactive mutants throughout that region all of which significantly perturbed oligomer formation. It was hypothesized that Y70 is playing an additional role necessary for CynD activity beyond influencing oligomerization. Here, we performed saturation mutagenesis at residue 70 and demonstrated that only tyrosine or phenylalanine is permissible for CynD activity. Furthermore, we show that other residues at this position are not only inactive, but have altered or disrupted oligomer conformations. These results suggest that Y70's essential role in activity is independent of its role in the formation of the spiral oligomer.

• Genomics & Informatics
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• 제12권2호
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• pp.71-75
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• 2014

The tRNA structure contains conserved modifications that are responsible for its stability and are involved in the initiation and accuracy of the translation process. tRNA modification enzymes are prevalent in bacteria, archaea, and eukaryotes. tRNA Gm18 methyltransferase (TrmH) and tRNA $m^1G37$ methyltransferase (TrmD) are prevalent and essential enzymes in bacterial populations. TrmH involves itself in methylation process at the 2'-OH group of ribose at the 18th position of guanosine (G) in tRNAs. TrmD methylates the G residue next to the anticodon in selected tRNA subsets. Initially, $m^1G37$ modification was reported to take place on three conserved tRNA subsets ($tRNA^{Arg}$, $tRNA^{Leu}$, $tRNA^{Pro}$); later on, few archaea and eukaryotes organisms revealed that other tRNAs also have the $m^1G37$ modification. The present study reveals Gm18, $m^1G37$ modification, and positions of $m^1G$ that take place next to the anticodon in tRNA sequences. We selected extremophile organisms and attempted to retrieve the $m^1G$ and Gm18 modification bases in tRNA sequences. Results showed that the Gm18 modification G residue occurs in all tRNA subsets except three tRNAs ($tRNA^{Met}$, $tRNA^{Pro}$, $tRNA^{Val}$). Whereas the $m^1G37$ modification base G is formed only on $tRNA^{Arg}$, $tRNA^{Leu}$, $tRNA^{Pro}$, and $tRNA^{His}$, the rest of the tRNAs contain adenine (A) next to the anticodon. Thus, we hypothesize that Gm18 modification and $m^1G$ modification occur irrespective of a G residue in tRNAs.

• 공업화학
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• 제23권2호
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• pp.195-203
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• 2012

폐 LCD유리의 재활용 방안은 평판 디스플레이용 폐 LCD판넬의 전체 재활용 공정의 확립을 위한 중심요건이다. 본 연구는 폐 LCD유리를 보온단열재, 흡음차음제, 토목용 경량골재 또는 수처리용 담체 등의 원료로 재활용하기 위한 발포공정의 기초공정으로서 폐 LCD유리의 분쇄특성, 적절한 탄소발포제의 선정, 유가물 회수를 위한 산침출 후 잔유된 유리질의 물성 및 이들의 발포화의 문제점을 조사하였다. 폐 LCD유리의 분쇄공정을 통해 발포용 원료로 사용가능한 미분화가 가능하였으며, 고융점을 갖는 LCD 유리의 발포화를 위해서는 결정성 천연흑연이 적절하였으며, 산 침출 후 잔사인 슬러지 상태의 폐유리성분도 발포체의 원료로 재활용될 수 있음을 확인하였다.