• Bulletin of the Korean Chemical Society
• /
• 제27권12호
• /
• pp.1989-1996
• /
• 2006

The $NiSO_4/CeO_2-ZrO_2 $catalysts containing different nickel sulfate and $CeO_2$ contents were prepared by the impregnation method, where support, $CeO_2-ZrO_2$was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and cerium nitrate solution followed by adding an aqueous ammonia solution. No diffraction line of nickel sulfate was observed up to 20 wt %, indicating good dispersion of nickel sulfate on the surface of $CeO_2-ZrO_2$. The addition of nickel sulfate (or $CeO_2$) to $ZrO_2$ shifted the phase transition of $ZrO_2$ from amorphous to tetragonal to higher temperatures because of the interaction between nickel sulfate (or $CeO_2$) and $ZrO_2$. A catalyst (10-$NiSO_4/1-CeO_2-ZrO_2$) containing 10 wt % $NiSO_4$ and 1 mole % $CeO_2$, and calcined at $600{^{\circ}C}$ exhibited a maximum catalytic activity for ethylene dimerization. The catalytic activities were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The role of $CeO_2$was to form a thermally stable solid solution with zirconia and consequently to give high surface area, thermal stability and acidity of the sample.

• BMB Reports
• /
• 제33권6호
• /
• pp.519-524
• /
• 2000

NF1 proteins are a family of DNA binding proteins which consist of two separate domains, N-terminal DNA binding domain and C-terminal transcription activation domain. The N-terminal 220 amino acids are highly conserved and are also known to mediate dimerization of NF1 proteins. The C-terminal regions of different type of NF1 proteins are heterogeneous and responsible for transcriptional activation. In this study, we tested the interaction between different domains of rat NF1-A protein by yeast two hybrid analysis and observed the interaction between C-terminal regions of NF1-A which do not contain the N-terminal dimerization domain. Our results showed that the C-terminal region of rat NF1-A between residues 231 and 509 strongly interacted not only with itself, but also with human NF1/CTF1 which is a different type of NF1. When the C-terminal region was divided into two fragments, one from residue 231 to 447 and the other from 448 to 509, the two fragments were able to interact with the C-terminal region of NF1-A significantly. This indicates that both fragments contain independent interaction domains. Analysis of the interactions with alanine substituted fragments showed that substitutions of the heptasequence, SPTSPTY of NF1-A, affected interaction between NF1 proteins. Our results strongly suggest that C-terminal regions may also be important for the formation of homo- and heterodimers in addition to the N-terminal dimerization domain. Also, the heptasequence motif may play some roles in dimer formation.

• 한국동물학회:학술대회논문집
• /
• 한국동물학회 1998년도 한국생물과학협회 학술발표대회
• /
• pp.283.1-283
• /
• 1998

No Abstract, See Full Text

• Bulletin of the Korean Chemical Society
• /
• 제27권8호
• /
• pp.1249-1252
• /
• 2006

• Bulletin of the Korean Chemical Society
• /
• 제15권12호
• /
• pp.1132-1133
• /
• 1994

• 대한약학회:학술대회논문집
• /
• 대한약학회 2001년도 Proceedings of International Convention of the Pharmaceutical Society of Korea
• /
• pp.158.1-158.1
• /
• 2001

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
• /
• pp.219-219
• /
• 2012

The formation and thermal desorption behaviors of octanethiol (OT) SAMs on single crystalline Au (111) and polycrystalline Au, Ag, and Cu substrates were examined by X-ray photoelectron microscopy (XPS), thermal desorption spectroscopy (TDS), and contact angle (CA) measurements. XPS and CA measurements revealed that the adsorption of octanethiol (OT) molecules on these metals led to the formation of chemisorbed self-assembled monolayers (SAMs). Three main desorption fragments for dioctyl disulfide (C8SSC8+, dimer), octanethiolate (C8S+), and octanethiol (C8SH+) were monitored using TDS to understand the effects of surface morphology and the nature of metal substrates on the thermal desorption behavior of alkanethiols. TDS measurements showed that a sharp dimer peak with a very strong intensity on single crystalline Au (111) surface was dominantly observed at 370 K, whereas a broad peak on the polycrystalline Au surface was observed at 405 K. On the other hand, desorption behaviors of octanethiolates and octanethiols were quite similar. We concluded that substrate morphology strongly affects the dimerization process of alkanethiolates on Au surfaces. We also found that desorption intensity of the dimer is in the order of Au＞＞Ag＞Cu, suggesting that the dimerization process occurs efficiently when the sulfur-metal bond has a more covalent character (Au) rather than an ionic character (Ag and Cu).

• BMB Reports
• /
• 제32권3호
• /
• pp.279-287
• /
• 1999

The aromatic hydrocarbon receptor (AhR) is a cytosolic protein that binds the environmental pollutant, dioxin. The liganded AhR translocates into the nucleus where it heterimerizes with a constitutive nuclear protein, AhR nuclear translocator (Arnt). The N-terminal regions of both AhR and Arnt contain basic helix-loop-helix (bHLH) and Per-AhR-Arnt-Sim (PAS) motifs that are required for DNA binding, dimerization, and ligand binding whereas the C-terminal regions of both AhR and Arnt contain transactivation domains. Here, results from the mammalian two-hybrid system indicate that Arnt can make a homodimer but AhR cannot. In the presence of dioxin, the interaction between AhR and Arnt is stronger than that of the Arnt homodimer, suggesting that Arnt prefers to make a heterodimer with the liganded AhR rather than a homodimer. Transfection analyses using the GAL4-driven reporter system suggest that AhR's N-terminal region represses its own transactivation domain, as well as exogenous transactivation domains such as Sp 1 and VP16. Interestingly, the repressed transactivation domains of AhR are activated by ligand-dependent heterodimerization with Arnt. These observations suggest that heterodimerzation with Arnt is necessary not only for DNA binding but also for activation of the repressed transactivation capability of AhR.

• BMB Reports
• /
• 제34권4호
• /
• pp.329-333
• /
• 2001

Active lipoprotein lipase (LPL) is known as a noncovalent homodimer of identical subunits, and dissociation of the dimer to a monomeric form renders the lipase inactive. In this study, the oligomerization status of LPL in human and rat plasma was investigated. The LPL activity was barely detectable in the control rat and human plasma. After the injection of heparin, the total lipolytic activity of plasma was rapidly increased, and reached its maximum in 30 min. Changes of the LPL protein correlated well with those of lipolytic activity. The LPL protein that is released by heparin into both human and rat plasma was active and dimeric in the sucrose density gradient ultracentrifugation. In control rat plasma, LPL was inactive, and a great fraction was present as an aggregate. However, the inactive LPL protein in the control human plasma retained the dimeric state, indicating that dimerization can be an entity independent of the catalytic activity of LPL. The released LPL is transported as a complex with lipoproteins in plasma. Lipoprotein profiles, determined by NaBr ultracentrifugation, exhibited typical LDL- and HDL-mammal patterns in humans and rats, respectively, with a smaller amount of the LDL fraction observed in rats. The difference in the lipoprotein profiles might influence the fate of the released LPL in plasma.

• 대한화학회지
• /
• 제8권4호
• /
• pp.135-141
• /
• 1964

아밀아이오다이드를 디메칠홀움아마이드 存在下에서 弗化加里와 低溫反應시켜 본 結果 弗化物과 데칸을 生成하였음. ${\alpha}$, ${\beta}$-디크로로-${\beta}$-페닐-푸로피온酸과 같은 多鹽素化物은 ${\alpha}$-크로로스타이렌, 弗化스타이렌 及 弗化酸을 生成하였음. 이 酸의 에칠에스텔은 弗化物을 生成하지 않고 各種 쌍合物의 混合物을 얻었음. 디부롬스타이렌은 부롬스타이렌과 弗化物을 生成하고 沃度를 含有한 有機酸, 메-타요드벤젠익酸은 有機酸의 鹽과 微量의 쌍合物을 生成하였음. 메타요드토류엔 及 1-아미노-4-요-드-2-메칠벤젠과 같은 沃化物은 弗化物은 弗化加里에 對하여 反應을 나타내지 않었음. 本報에는 各 反應條件과 弗化反應, 脫炭酸反應 及 쌍合反應에 關하여 論義하였음.