• Journal of the Korean Magnetic Resonance Society
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• v.2 no.2
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• pp.131-140
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• 1998

The calcium-induced structural changes in the skeletal muscle regulatory protein troponin C (NTnC) involve a transition from a ‘closed’to an ‘open’structure with the concomitant exposure of a large hydrophobic interaction site for target proteins. Structural studies have served to define this conformational change and elucidate the mechanism of the linkage between calcium binding and the induced structural changes. There are now several structures of NTnC available from both NMR and X-ray crystallography. Comparison of the calcium bound structures reveals differences in the level of opening. We have considered the concept of a flexible open state of NTnC as a possible explanation for this apparent discrepancy. We also present simulations of the closed-to-open transition which are in agreement with the flexibility concept and with experimental energetics data.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.16-18
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• 1997

The adhesion of stimulated and unstimulated platelet to fibrinogen requires the receptor binding site of GPIIb/IIIa. These recognition sites are existed in the Au chain(RGDS at positions 572-575 and RGDF at 95-98) and the carboxyterminal $\gamma$ chain (HHLGGAKQAGDV at 400-411) of fibrinogen. The unstimulated platelet does not adhered on the fragment E-coated surface containing RGDF sequence. In this study, we developed RGDF-immobilized surface to detect the functional state of platelet. RGDF-immobilized surface was prepared on the glass using photolithographic technology. Platelet adhesion to petide(RGDF)-immobilized surface was observed by the fluorescence microscope using mepacrine.

• Korean Journal of Materials Research
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• v.15 no.3
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• pp.209-215
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• 2005

Titanium dioxide films $(TiO_2)$ doped cobalt transition metal were prepared on titanium metal by water spray pyrolysis technique. Micro-morphology, crystalline structure, chemical composition and binding state of sample groups were evaluated using field emission scanning microscope(FE-SEM), X-ray diffractometer(XRD), Raman spectrometer, X-ray photoelectron spectrometer(XPS). $TiO_2$ films of rutile structure were predominately formed on all sample groups and $Ti_2O_3$ oxide was coexisted on the surface of cobalt doped-sample groups. The optical absorption peaks measured by using UV-VIS-NIR spectrophotometer were observed at specific wavelength region in sample groups doped cobalt ion. This result could be analyzed by introducing crystal field theory.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.197-201
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• 2008

Conformational heterogeneity of directly linked multiporphyrin arrays with larger molecular length retards their utilities in practical applications such as two-photon absorption and molecular photonic wire. In this regard, here we adopted a way to overcome the conformational heterogeneity through hydrogen bonding by selective binding of meso aryl substituents of porphyrins (host) with urea (guest) to form helical structure. Using steady-state and time-resolved spectroscopy, we observed the enhanced fluorescence quantum yield by ~1.8 to 2.4 times, enhanced anisotropy values and the disappearance of fast fluorescence decay component in the host-guest helical forms. In addition, the enhanced nonlinear optical responses of helical arrays infer the extended inter-porphyrin electronic coupling due to a significant change in dihedral angle between the neighboring porphyrin moieties. The current host-guest strategy will provide a guideline to improve the structural homogeneity of the photonic wire.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.69-75
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• 2008

Tautomerism of pyrimidine base cytosine has been comparatively examined on nanoparticle and roughened plate surfaces of silver, gold, and copper by surface-enhanced Raman scattering (SERS). The SERS spectrum was found to be different depending on the metals and their substrate conditions suggesting the dissimilar population of various tautomers of cytosine on the surfaces. The ab initio calculations were performed at the levels of B3LYP, HF, and MP2 levels of theory with the LanL2DZ basis set to estimate the energetic stability of the tautomers with the metal complexes as well as the gas phase state. The amino group and N3-coordinated tautomer was predicted to be more favorable for bonding to Au, whereas the hydroxyl and N1-coordinated zwitter ionic form is most stable with Ag and Cu as a bidentate form from the DFT calculation. The binding energy with the Ag atom is calculated to be smaller than those with the Au and Cu atoms in line with the temperature-dependent SERS spectra of cytosine.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.912-916
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• 2013

The electronic structure of LaFeAsO was analyzed by tight-binding band calculation based upon the normal and shrunk lattices. A strong Fermi surface nesting was found in the normal LaFeAsO, while most of the nesting area was disappeared in the shrunk LaFeAsO. It was found, therefore, high pressure atmosphere is required to become a superconductor for LaFeAsO by suppressing the SDW (spin density wave) state through the disappearance of the Fermi surface nesting.

• Rapid Communication in Photoscience
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• v.1 no.2
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• pp.58-58
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• 2012

• Journal of Photoscience
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• v.4 no.1
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• pp.1-5
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• 1997

A hitherto unknown diphenylbutadiene analog viz. 1-(p-N,N-dimethylaminophenyl)-4-phenyl-2-methyl-1E,3E-butadiene (10) has been prepared and its absorption, excitation, and fluorescent emission properties in different media including various organic solvents and aqueous bovine serum albumin (BSA) have been studied. For comparision, these properties have also been investigated for the parent diphenylbutadiene (2). Diene 10 exhibits solvent polarity/polarizability-sensitive fluorescence properties ($\lambda$$_{max}$, $\Phi$$_f$, $\tau$$_f$, K$_f$, f). It also binds to the hydrophobic domains of aqueous bovine serum albumin (BSA) with a binding constant of 3.89 x 10$^4$ M$^{-1}$. The relative fluorescence quantum yield of 10 increases, while, the fluorescence lifetime decreases with increasing concentration of-BSA. The results highlight the polar character of the singlet excited state of diphenylpolyenes and the utility of 10 as fluorescence probe for studying microenvironments of organized assemblies and biological supramolecular structures.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1670-1674
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• 1998

Now and then there are many electrical accidents between cable and line post insulator which is degraded by long time using, causing leakage current on the surface of insulator. In this paper it is denied that the 22.9 KV-y distribution lines are protected by binding cover which is needed from fog or rainy moisture, surges occurring by swiching or lightening pulse. It is analyzed to investgate the unballanced transfer characteristics and reflection coefficient by using bidding cover and non-cover. It was tested the radio interference voltage in the test room. In the factory it was tested the amount of leakage current causing on the surface of insulator in the state of no load and 70(%) load.

• YAKHAK HOEJI
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• v.39 no.3
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• pp.329-336
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• 1995

Conformational free energy calculations using an empirical potential function and a hydration shell model(program CONBIO) were carried out on hypoglycemic agent acetohexamide and tolazamide in the unhydrated and hydrated states. The initial geometry of sulfonylureas was obtained from X-ray crystallographieal data and homologous molecular fragments. In both states, the feasible conformations were obtained from the calculations of conformational energy, conformational entropy, and hydration free energy by varying all the torsion angles of the molecules. From the calculation results, it is known that the conformations] entropy is the major contribution to stabflize the low-free-energy conformations of two sulfonylureas in both states. But, in hydrated state, the hydration does not directly affect each conformations. The intramolecular hydrogen bonding of sulfonylurea hydrogen and 7-membered nitrogen appeared to the conformations of tolazamide in both states. It is thought that the hydrogen bonding decrease steric hindrance on the receptor binding direction. The substitution of alicyclic or N-heterocyclic ring than that of carbons chain of urea moiety may be properly interaction between sulfonylureas and the putative pancreatic receptor.