• Molecules and Cells
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• 제46권4호
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• pp.256-257
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• 2023

• Bulletin of the Korean Chemical Society
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• 제34권9호
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• pp.2663-2670
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• 2013

The purpose of stability testing is to provide evidence about how the quality of a drug varies with time under the influence of a variety of environmental factors. In this study, erythropoietin (EPO) was analyzed under different pH (pH 3 and pH 9) and temperature ($25^{\circ}C$ and $40^{\circ}C$) conditions according to current Good Manufacturing Practice (cGMP) and International Conference on Harmonisation (ICH) guidelines. The molecular weight difference between intact EPO and deglycosylated EPO was determined by SDS-PAGE, and aggregated forms of EPO under thermal stress and high-pH conditions were investigated by size exclusion chromatography. High pH and high temperature induced increases in dimer and high molecular weight aggregate forms of EPO. UPLC-ESI-TOF-MS was applied to analyze the changed modification sites on EPO. Further, normal-phase high-performance liquid chromatography was performed to identify proposed glycan structures and high pH anion exchange chromatography was carried out to investigate any change in carbohydrate composition. The results demonstrated that there were no changes in modification sites or the glycan structure under severe conditions; however, the number of dimers and aggregates increased at $40^{\circ}C$ and pH 9, respectively.

• Fibers and Polymers
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• 제3권1호
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• pp.18-23
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• 2002

The structure development and dynamic properties of fibers produced by high-speed spinning of P(EN-ET) random copolymers were investigated. The as-spun fibers were found to remain amorphous up to the spinning speed of 1500 m/min, and subsequent increases in speed resulted in the crystalline domains containing primarily $\alpha$ crystalline modification of PEN. The f modification was not found up to spinning speeds of 4500 m/min. On the other hand, annealing of constrained fibers spun at the 2100 m/min at 180,200, and 240^{\circ}C$ exhibited $\beta$-form crystalline structure, while the annealed fibers spun in 600-1500 m/min range exhibited dominantly $\alpha$-form. However $\beta$-form crystals disappeared above the spinning speed of 3000 m/min. With increasing spinning speeds from 600 to 4500 m/min, the storage modulus of as-spun fibers increased continuously and reached a value of about 10.4 spa at room temperature. The tan $\delta$curves showed the $\alpha$-relaxation peak at about 155-165^{\circ}C$, which is considered to correspond to the glass transition. The $\alpha$-relaxation peaks became smaller and broader, and shift to higher temperatures as the spinning speed increases, meaning that molecular mobility in the amorphous region is restricted by increased crystalline domain.

• Journal of Applied Biological Chemistry
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• 제53권3호
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• pp.121-125
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• 2010

지난 10년간 분자 식물 일주기성에 대해 분자 생물학적, 생화학적인 연구가 많이 진행되었다. 본 연구에서는 식물의 Arabidopsis, rice 그리고 algae에서 지금까지 발표된 연구들을 종합하고 고찰해보려 했다. 그 결과, 아직까지도 주기성 대사의 모든 부분을 설명하기엔 부족한 부분이 많다는 것을 알수 있었다. 최근 주기성 단백질들의 전사후, 번역 그리고 번역후 변형과정에 대해 많은 연구자들이 관심을 갖기 시작했다. 이러한 부분에서 다량의 단백질을 한번에 볼 수 있는 2-DE gel electrophoresis와 MS/MS 기술이 절실히 요구된다고 할 수 있겠다.

• 한국식품영양학회지
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• 제3권2호
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• pp.123-132
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• 1990

Sweet potato $\beta$-amylase is a tetrameric enzyme consisting of four identical polypeptide chains with a molecular weight of 5.6$\times$104, though most of the other $\beta$-amylases are monomeric enzymes. But, the relationship between subunit structure and catalytic function of the enzyme is not known. This study was done to know what the function of the subunit structure of the enzyme is. We obtained the monomer from the enzyme by the treatment of SDS, alkali pH buffer and urea. But the monomer had not activity. We tried to prepare the active monomer from the enzyme by the modification with periodate-oxidized soluble starch , In the result, we succeeded in isolating an active monomer as an oxidized soluble starch-conjugated form The active monomer had 57% of the original activity, 13.2% of the sugar and the molecular weight was estimated to be 5.4$\times$104. This results suggest that the tetrameric form of the enzyme is a most stable one and exists in nature, and the subunit structure of the enzyme Plays an important role in stabilization but not catalytic function.

• Molecules and Cells
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• 제25권3호
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• pp.347-351
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• 2008

Several lines of evidence indicate that the oxidative modification of protein and the subsequent accumulation of the modified proteins have been found in cells during aging, oxidative stress, and in various pathological states including premature diseases, muscular dystrophy, rheumatoid arthritis, and atherosclerosis. The important agents that give rise to the modification of a protein may be represented by reactive aldehydic intermediates, such as ketoaldehydes, 2-alkenals and 4-hydroxy-2-alkenals. These reactive aldehydes are considered important mediators of cell damage due to their ability to covalently modify biomolecules, which can disrupt important cellular functions and can cause mutations. Furthermore, the adduction of aldehydes to apolipoprotein B in low-density lipoproteins (LDL) has been strongly implicated in the mechanism by which LDL is converted to an atherogenic form that is taken up by macrophages, leading to the formation of foam cells. During the search for an endogenous inducer of cyclooxygenase-2 (COX-2), an inducible isoform responsible for high levels of prostaglandin production during inflammation and immune responses, 4-hydroxy-2-noennal (HNE), one of the most representative lipid peroxidation product, has been identified as the potential inducer of COX-2. In addition, the following study on the molecular mechanism of the COX-2 induction by HNE has unequivocally established that a serum component, which is eventually identified to be denatured LDL, is essential for COX-2 induction. Here I review current understanding of the mechanisms by which HNE in cooperation with the serum component activates gene expression of COX-2.

• Molecules and Cells
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• 제25권3호
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• pp.332-346
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• 2008

S-glutathionylation is a reversible post-translational modification that continues to gain eminence as a redox regulatory mechanism of protein activity and associated cellular functions. Many diverse cellular proteins such as transcription factors, adhesion molecules, enzymes, and cytokines are reported to undergo glutathionylation, although the functional impact has been less well characterized. De-glutathionylation is catalyzed specifically and efficiently by glutaredoxin (GRx, aka thioltransferase), and facile reversibility is critical in determining the physiological relevance of glutathionylation as a means of protein regulation. Thus, studies with cohesive themes addressing both the glutathionylation of proteins and the corresponding impact of GRx are especially useful in advancing understanding. Reactive oxygen species (ROS) and redox regulation are well accepted as playing a role in inflammatory processes, such as leukostasis and the destruction of foreign particles by macrophages. We discuss in this review the current implications of GRx and/or glutathionylation in the inflammatory response and in diseases associated with chronic inflammation, namely diabetes, atherosclerosis, inflammatory lung disease, cancer, and Alzheimer's disease, and in viral infections.

• 접착 및 계면
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• 제20권2호
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• pp.71-75
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• 2019

탄닌산은 식물계에서 가장 많이 발견되는 폴리페놀 중 하나로, 초기 탄닌산 연구는 항산화제 등과 같은 생리학적 기능에 집중되어 있었다. 그러나 최근에는 탄닌산이 단백질, DNA 등 거의 모든 생체고분자와 분자간결합을 하는 것이 밝혀짐에 따라 분자적 접착제로서 많은 관심을 받고 있다. 탄닌산의 다양한 특성들은 표면의 기능, 젖음성을 조절할 뿐 아니라 에너지 저장 및 발생 장치에 기여하고, 의학적 제재로의 다양한 가능성을 보이고 있다. 본 논문에서는 분자적 접착제로서의 탄닌산과 생체고분자와의 결합, 탄닌산을 통한 표면 개질, 의료용 제재로의 활용 등에 대해 다루고자 한다.

• Mass Spectrometry Letters
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• 제6권1호
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• pp.1-6
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• 2015

Direct analysis in real time mass spectrometry (DART-MS) is one of the variants of ambient mass spectrometry. The ionization process of DART-MS is in open environment and only takes few seconds, so it is suitable for fast analysis. Actually, since its introduction in 2005, more and more attentions have been drawn to its various applications due to its excellent properties, e.g., fast analysis, and no or less sample preparation, high salt tolerance and so on. This review summarized the promising features of DART-MS, including its ionization mechanism, equipment modification, wide applications, coupling techniques and extraction strategies before analysis.

• Journal of Microbiology and Biotechnology
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• 제16권7호
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• pp.1090-1096
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• 2006

O-Methylation is a common modification reaction found in nature, and is mediated by an O-methyltransferase (OMT). OMTs have been mainly studied in plants, whereas only a few OMTs have been studied in microbes. When searching the Bacillus cereus genome, four putative small molecular OMTs were identified, among which BcOMT-1 was cloned and expressed in E. coli as a his-tag fusion protein. The whole cell expressing BcOMT-1 was used to methylate several flavonoids. Eriodictyol, luteolin, quercetin, and taxifolin, all of which contain 3' and 4' hydroxyl groups, served as methyl group acceptors for BcOMT-1, whereas naringenin, apigenin, 3,3'-dihydroxyflavone, and 3,4'-dihydroxyflavone did not function as substrates. Analysis of the reaction products using HPLC showed two different peaks, and NMR revealed that the methylation position was at the hydroxyl group of either carbon 3' or 4'. Therefore, this showed that BcOMT-1 used flavonoids containing ortho hydroxyl groups and transferred a methyl group to either of two hydroxyl groups.