• Title/Summary/Keyword: 이분자

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Structural Studies of Membrane Protein by Solid-state NMR Spectroscopy (고체상 핵자기공명 분광법을 이용한 막단백질의 구조연구)

  • Kim, Yongae
    • Analytical Science and Technology
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    • v.17 no.5
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    • pp.388-392
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    • 2004
  • Structural studies of membrane proteins, importantly involving interpretation of genomics information, many signaling pathway and major drug target for drug discovery, are having difficulty in characterizing the function using conventional solution nmr spectroscopy and x-ray crystallography because phospholipid bilayers hindered fast tumbling and crystallization. Here, we studied the structure of the pf1 coat protein in oriented phospholipid bilayers by home-built solid-state NMR probe. Bacteriophage pf1 was purified from Paeudomonas Aeruginosa and coat protein of bacteriophage pf1 was isolated from DNA and other proteins.

Synthesis and Characterization of Intercalation Compounds of Alkylsulfonate into Hydrated and Dehydrated Zinc (수화된 아연과 탈수된 아연에 알킬술폰이 층간 삽입된 화합물의 합성과 구조)

  • Huh, Young Duk;Park, Sung Hun;Jun, Tae Hyun;Park, Yong Jun;Park, Yang Sun
    • Analytical Science and Technology
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    • v.13 no.3
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    • pp.338-345
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    • 2000
  • The intercalated compounds of alkylsulfonate into hydrated and dehydrated zinc were synthesized. From the XRD, FT-IR, TGA, elemental analysis data, and the molecular size, the orientation of the intercalated alkylsulfonates was determined. For the hydrated compounds, alkylsulfonates were intercalated into hexaqua zinc layer with the bilayer structure of $32.9^{\circ}$ angle of inclination. For the dehydrated compounds, alkylsulfonates were directly bonded to zinc ion with the bilayer structure of $51.4^{\circ}$ angle of inclination.

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MO Studies on Nucleophilic Substitution Reaction (친핵성 치환반응에 대한 분자궤도론적 연구)

  • Bon Su Lee;Lee, Ik Choon;Ki Yull Yang
    • Journal of the Korean Chemical Society
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    • v.25 no.3
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    • pp.145-151
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    • 1981
  • The intrinsic reactivity of $S_N2$reaction in the gas phase was discussed MO theoretically (CNDO/2). We investigated the changes in geometry and electronic structure by means of the partial geometry optimization for reactantes, transition states, and products with various nucleophiles and leaving groups. We found that it was possible to discuss qualitatively the reactivity of $S_N2$ reaction with CNDO/2 MO calculation and the reactivity was controlled by basicity and of induced polarizability.

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Studies Towards Intramolecular Formal Iron-Catalyzed [4+2] Cycloaddition of Acetylenic Dienes (Fe(0) 촉매를 이용한 Acetylenic Dienes 의 분자내 [4+2] 고리화 첨가반응에 관한 연구)

  • Byeon, Sang Yong
    • Journal of the Korean Chemical Society
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    • v.38 no.1
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    • pp.61-68
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    • 1994
  • The intramolecular formal iron-catalyzed [4+2] cycloaddition reaction of acetylenic dienes to produce bicyclic products has been investigated. These reactions proceeded, competing via intramolecular carbocyclization and bimolecular cycloaddition. However, the iron-catalyzed bicyclic carbocyclization of 4,4-dimethyl-3-(tert-butyldimethylsiloxy)-1-phenyl-6,8-decadien-1-yne(11) yielded exclusively bicyclic diene product(yield 78.1%). From this result, we found that the substrate containing a dimethyl substitutent at the 4,4-position helped to promote the intramolecular reaction, which is stable to the iron catalyzed conditions.

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Bilayer Formation and Functional Design of Synthetic Amphiphiles as Biometmbrane Model (생체막 모델로서 합성 양친매성 화합물의 이분자층 형성과 기능성 설계)

  • 김종목
    • Membrane Journal
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    • v.2 no.2
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    • pp.112-121
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    • 1992
  • 최근 십여년동안 자원, 에너지, 환경의 모든 면에서 기능성막의 역할이 증대해짐에 따라 기능성막에 대해 큰 관심이 모아지고 있다. 기존하는 기능성막의 소재면에서 볼 때 고분자막(고체막), 액체막으로 대별할 수 있으며, 이들의 경우 해수의 담수화, 원료 및 제품의 분리, 농축, 정제, 회수공정 또한 석유화학분야에서 고효율$\cdot$고선택성 기체혼합물 분리, 산업용 폐수처리분야 뿐 만 아니라, 태양에너지의 효과적인 이용, 전도성, 감광성, 광학특성막 등을 이용한 각종 센서제조 등 실로 광범위한 분야에서 응용되어지고 있다. 기능성막의 관점에서 볼 때, 고기능$\cdot$고효율$\cdot$고선택성을 가지는 막은 생태계에 존재하는 생체막이 가장 이상적이라 할 수 있다.

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Exchange Reaction Mechanism of $Pb(II)-N_2O_m$ Macrocyclic Complexes by $^{207}Pb-NMR$ Spectroscopy ($^{207}Pb-NMR$ 분광법에 의한 $Pb(II)-N_2O_m$계 거대고리 리간드 착물형성 반응의 교환 메카니즘)

  • Kim, Jeong;Yun, Chang Ju;Yu, Han Jun;Kim, Geon;Kim, Si Jung
    • Journal of the Korean Chemical Society
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    • v.38 no.1
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    • pp.41-49
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    • 1994
  • Exchange reaction mechanisms of the Pb(II) ion for the complexes between Pb(II) ion and nitrogen oxygen donor macrocyclic ligands, such as 1,13-diaza-3,4 : $1011-dibenzo-59-dioxacyclohexa-decane(NtnOtnH_4)$, 1,15-diaza-3,4 : $1213-dibenzo-5811-trioxacycloheptadecane(NenOdienH_4)$, and 1,15-diaza-3,4 : $1213-dibenzo-5811-trioxacyclooctadecane(NtnOdienH_4)$, were studied by $^{207}Pb-NMR$ spectroscopy in N,N'-dimethylformamide(DMF) solutions. The associative-dissociative mechanism dominated in $NtnOtnH_4-Pb(II)$ and $NtnOdienH_4-Pb(II)$ system. For $NenOdienH_4-Pb(II)$ system, the bimolecular exchange mechanism prevailed below $-5^{\circ}C$, and both bimolecular exchange and associative-dissociative mechanism dominated above $+5^{\circ}C.$ The order of activation energies for dissociation was $NtnOdienH_4\;<\;NtnOtnH_4\;<\;NenOdienH_4$ which was reverse to the order of stabilities.

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Theoretical Studies on the Cationic Polymerization Mechanism of Oxetanes(II) ($BF_3$촉매하의 옥세탄 공중합에 관한 분자 궤도론적 연구)

  • Park, Jeong Hwan;Cho, Sung Dong;Park, Seong Kyu;Cheun, Young Gu
    • Journal of the Korean Chemical Society
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    • v.40 no.1
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    • pp.11-19
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    • 1996
  • The cationic polymerization of energetic substituted oxetanes which have pendant energetic group such as azido and nitrato are investigated theoretically, using semiempirical HF/3-21G, MINDO/3, MNDO and AM1 method. The stereo- and electronic structure of binary molecular complex composed of energetic substituted oxetane and boron trifluoride can be explain by molecular orbital theory. The reactivity of propagation in the copolymerization of oxetanes can be presented by the positive charge on carbon(C2) atom of oxetane and energy level of the lowest unoccupied molecular orbital(LUMO) of propagating species of oxetanes. The reactivity ratios for copolymerization of oxetanes are a random copolymer-zation which is agree with MO calculated and experimental results. The relative equlibrium concentration of cyclic oxonium and open carbenium ions is found to be a major determinant of mechanism, owing to the rapid equilibrium of these cation forms and the expectation based on calculation that in the prepolymer propagation step, SN1 mechanism will be at least as fast as that for SN2 mechanism.

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Synthesis of TiO2 Fine Powder by Sol-Gel Process and Reaction Mechanism(I): Hydrolysis of Titanium Isopropoxide (졸-겔법에 의한 TiO2 미분말 합성과 반응메카니즘(I): Titanium isopropoxide의 가수분해)

  • Myung, Jung-Jae;Chung, Yong-Sun;Kyong, Jin-Bum;Kim, Ho-Kun
    • Applied Chemistry for Engineering
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    • v.7 no.4
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    • pp.794-801
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    • 1996
  • $TiO_2$ fine powders were synthesized via hydrolysis reaction of titanium isopropoxide in isopropanol solvent and the reaction rates were studied by use of UV spectroscopic method. The reactions were controlled to proceed to pseudo-first-order reaction in the presence of excess water in isopropanol solvent. The rate constants which varied with temperature and concentration of water were calculated by Guggenheim method. Reactions using $D_2O$ were also carried out to determine the catalytic character of water. n value of water molecules in transition state and the thermodynamic parameters showed that the reaction proceeded by $S_N2$ mechanism. $TiO_2$ powders synthesized in this reaction were almost spheric forms and had average particle size of $0.3{\mu}m$ diameter.

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The Effect of Pressure on the Rate of Solvolysis(Ⅱ). Reactions of Methyl-, Phenyl Chloroformate and 1-Adamantyl Derivatives (가용매분해반응에 대한 압력의 영향(Ⅱ). Methyl-, Phenyl Chloroformate와 1-Adamantyl 유도체에 대한 반응)

  • Kwun, Oh Cheun;Kim, Jeong Rim;Kyong, Jin Burm;Lee, Young Hoon;Kim, Jong Chul
    • Journal of the Korean Chemical Society
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    • v.40 no.5
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    • pp.327-332
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    • 1996
  • The rates of solvolylsis of methyl chloroformate, phenyl chloroformate and 1-adamantyl derivatives in binary solvent mixtures have been measured by conductometric method at various temperatures and pressures. The activation parameters were estimated from the rate constants. The activation volume (${\Delta}V_o^{\neq}$) and the activation entropy (${\Delta}S^{\neq}$) are both negative, but the activation enthalpy (${\Delta}H^{\neq}$) is positive. This behavior is discussed in terms of electrostriction of solvation. The reactivities of these reactions were also estimated from the correlation of the activation volumes with the activation entropies. From these results, it could be estimated that the solvolyses of 1-adamantyl fluoroformate (in aqueous TFE) and 1-adamantyl tosylate have pathway involving unimolecular reaction, while the reaction of methyl chloroformate, phenyl chloroformate and 1-adamantyl fluoroformate (in aqueous alcohol) proceed through a bimolecular reaction.

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