• 제목/요약/키워드: thiol

검색결과 426건 처리시간 0.027초

카르보닐 탄소원자의 친핵치환 반응 (제4보). Phenyl Chloroformate에 대한 EHT 계산 (Nucleophilic Substitution at a Carbonyl Carbon Atom (IV). EHT Calculations on Phenyl Chloroformate)

  • 이익춘;김의洛;이명재;서배석
    • 대한화학회지
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    • 제18권3호
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    • pp.175-179
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    • 1974
  • Phenyl chloro-thiol, phenyl chloro-thiono 와 phenyl dithioformate에 분자궤도 함수론을 적용하여 계산 연구한 결과 모든 경우 trans형이 더 안정하며 또 SN반응기구는$ S_N2$형으로 일어날 가능성이 큼을 밝혔다

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주사탐침현미경을 이용한 기능성분자 패터닝 (Direct Patterning of Functional Molecules using Scanning Probe Microscope)

  • 윤완수;석성대;박형주;하동한;장원석;신보성
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2003년도 춘계학술대회
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    • pp.1048-1051
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    • 2003
  • 주사탐침현미경 (Scanning Probe Microsope, SPM)을 이용하여 직접 패터닝을 함으로써 hexanedithiol 분자의 임의 패턴을 금 표면에 형성하였다. 또한, hexanedithiol 분자는 양단에 thiol 그룹이 존재하여 금과 안정화 화학결합을 이룰 수 있으므로, 금 표면과결합을 이루고 있지 않는 상단의 thiol 그룹에 금 나노 입자를 고정함으로써 나노입자의 패턴을 제작하였다. SPM을 이용한 직접 패터닝 방법은 분자활성을 유지한 채로 임의 패턴을 수십 nm의 선폭으로 구현하는 것이 가능하므로, 나노입자 배열뿐만 아니라, 생화학물질의 패터닝을 통한 바이오 기술연구, 레지스트용 분자 패터닝과 시각 및 흡착 등의 계속적인 공정을 통한 다양한 나노구조 제작 등에 폭넓게 활용될 수 있다.

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Numerical Identification of a Streptomyces Strain Producing Thiol Protease Inhibitor

  • Lee, Kye-Joon;Kim, In-Seop;Kim, Hyoun-Tae;Ward, Alan-C.;Goodfellow, Michael
    • Journal of Microbiology and Biotechnology
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    • 제2권3호
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    • pp.220-225
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    • 1992
  • Chemotaxonomic and numerical identification were carried out for an isolate of Streptomyces strain SMF13 producing thiol protease inhibitor. Fifty taxonomic unit characters were tested and the data were analyzed numerically using the TAXON program. The isolate SMF13 was identified to be a member of the cluster 5 of Streptomyces and best matched to Streptomyces omiyaensis which is a synonym of Streptomyces exfoliatus. Therefore. it was concluded that the isolate was identified to be a strain of Streptomyces exfoliatus.

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Sulforaphane Inhibits Osteoclastogenesis by Inhibiting Nuclear Factor-κB

  • Kim, Soo-Jin;Kang, So-Young;Shin, Hyun-Hee;Choi, Hye-Seon
    • Molecules and Cells
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    • 제20권3호
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    • pp.364-370
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    • 2005
  • We show that sulforaphane inhibits osteoclastogenesis in the presence of macrophage colony-stimulating factor (M-CSF) and receptor for activation of nuclear factor-${\kappa}B$ ligand (RANKL) in osteoclast (OC) precursors. Sulforaphane, an aliphatic isothiocyanate, is a known cancer chemo-preventative agent with anti-oxidative properties. Nuclear factor-${\kappa}B$ (NF-${\kappa}B$) is a critical transcription factor in RANKL-induced osteoclastogenesis, and electrophoretic mobility shift assays (EMSAs) and assay of NF-${\kappa}B$-mediated secreted alkaline phosphatase (SEAP) revealed that sulforaphane selectively inhibited NF-${\kappa}B$ activation induced by RANKL. Inhibition may involve interaction of sulforaphane with thiol groups, since it was prevented by reducing agents.

Redox-Dependent Modulation of RsrA, an Anti-Sigma Factor Regulating Thioredoxin Operons in Streptomyces coelicolor

  • Bae, Jae-Bum;Park, Joo-Hong;Roe, Jung-Hye
    • 한국생물물리학회:학술대회논문집
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    • 한국생물물리학회 2002년도 제9회 학술 발표회 프로그램과 논문초록
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    • pp.54-54
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    • 2002
  • $\sigma$$\^$R/ is a sigma factor responsible for inducing the thioredoxin system in response to oxidative stress in Streptomyces coelicolor. RsrA, an anti-sigma factor, specifically binds to $\sigma$$\^$R/ and inhibits $\sigma$$\^$R/-directed transcription under reducing conditions. Exposure to H$_2$O$_2$ or thiol-specific oxidant diamide dissociates $\sigma$$\^$R/-RsrA complex. The redox-dependent regulation of $\sigma$$\^$R/-RsrA binding has been reported to involve thiol-disulfide exchange in RsrA, which contains 7 cysteines in 105 amino acid residues.(omitted)

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가황(加黃)고무의 물리적(物理的) 성질(性質)에 미치는 가교구조(架橋構造)의 영향(影響) (The Effect of Crosslink Structures on the Physical Properties of Carbon Black Filled NR and SBR Vulcanizates)

  • 김상구
    • Elastomers and Composites
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    • 제23권4호
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    • pp.299-307
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    • 1988
  • The mono-, di- and polysulfidic concentrations of the carbon black filled NR and SBR vucanizates which have different cure systems were determined. The n-decane was used as a swelling solvent. The propane-2-thiol and hexane thiol were used as specific chemical probes to cleavage the chemical crosslinks such as di- and polysulfide. In order to understand the effect of crosslink structure on the physical properties of vulcanizates, the tensile properties, fatigue failure, heat build up, compression set and viscoelastic properties were measured. From the results, the significant relationships between crosslink sturctures and physical properties, especially a gins resistance were obtained. Therefore, the better performances of the product can be satisfied by using the interpretations and approaches in this study.

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Changes of Thiols and Oxidative Stress in Tomato Seedlings Exposed to Cadmium

  • Cho, Un-Haing;Seo, Nam-Ho
    • Journal of Ecology and Environment
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    • 제29권1호
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    • pp.61-67
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    • 2006
  • Tomato (Lycopersicon esculentum Mill) seedlings exposed to various concentrations of $CdCl_2(0{\sim}100{\mu}M)$ in a nutrient solution for up to 9 days were analyzed with respect to the thiol changes and oxidative stress. The Cd exposure increased total non-protein thiols (NPT) and cysteine in both leaves and roots, total glutathione in leaves, and the ratios of oxidized glutathione (GSSG)/reduced glutathione (GSH) in both leaves and roots, but decreased the ratio of dehydroascorbate (DASA)/ascorbate(ASA) in leaves. Our results suggest that the Cd-induced GSH depletion due to thiol synthesis and oxidation alters the antioxidant activity of seedlings for $H_2O_2$, and the subsequent $H_2O_2$ accumulationand oxidative stress result in phytotoxicity.

Thiol-Based Peroxidases and Ascorbate Peroxidases: Why Plants Rely on Multiple Peroxidase Systems in the Photosynthesizing Chloroplast?

  • Dietz, Karl-Josef
    • Molecules and Cells
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    • 제39권1호
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    • pp.20-25
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    • 2016
  • Photosynthesis is a highly robust process allowing for rapid adjustment to changing environmental conditions. The efficient acclimation depends on balanced redox metabolism and control of reactive oxygen species release which triggers signaling cascades and potentially detrimental oxidation reactions. Thiol peroxidases of the peroxiredoxin and glutathione peroxidase type, and ascorbate peroxidases are the main peroxide detoxifying enzymes of the chloroplast. They use different electron donors and are linked to distinct redox networks. In addition, the peroxiredoxins serve functions in redox regulation and retrograde signaling. The complexity of plastid peroxidases is discussed in context of suborganellar localization, substrate preference, metabolic coupling, protein abundance, activity regulation, interactions, signaling functions, and the conditional requirement for high antioxidant capacity. Thus the review provides an opinion on the advantage of linking detoxification of peroxides to different enzymatic systems and implementing mechanisms for their inactivation to enforce signal propagation within and from the chloroplast.

Kinetic Approaches to Measuring Peroxiredoxin Reactivity

  • Winterbourn, Christine C.;Peskin, Alexander V.
    • Molecules and Cells
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    • 제39권1호
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    • pp.26-30
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    • 2016
  • Peroxiredoxins are ubiquitous thiol proteins that catalyse the breakdown of peroxides and regulate redox activity in the cell. Kinetic analysis of their reactions is required in order to identify substrate preferences, to understand how molecular structure affects activity and to establish their physiological functions. Various approaches can be taken, including the measurement of rates of individual steps in the reaction pathway by stopped flow or competitive kinetics, classical enzymatic analysis and measurement of peroxidase activity. Each methodology has its strengths and they can often give complementary information. However, it is important to understand the experimental conditions of the assay so as to interpret correctly what parameter is being measured. This brief review discusses different kinetic approaches and the information that can be obtained from them.