• Bulletin of the Korean Chemical Society
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• 제4권3호
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• pp.133-139
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• 1983

To understand the importance of Y-base adjacent to the anticodon stabilizing codon-anticodon interaction, a study has been undertaken for the model compound involving the interaction between Y-base and anticodon as well as the participation of water molecule by calculating the conformational free energy using an empirical potential function. We restrict our analysis to sites directly associated with Y-base by varying only the backbone torsion angles of Y-base. The hydration and $Mg^{+2}$ binding effects on the conformational stability of Y-base are calculated and discussed. The free Y-base is proved to be less stable than the hydrated one. The free energy change due to the hydration of Y-base amounts to -119.5 kcal/mole, in which the conformational energy change is -142.4 kcal/mole and the configurational entropy change is -76.9 e. u. It is found that the water molecules bound to Y-base and $Mg^{+2}$ contribute to the conformation of Y-base dominantly.

• Bulletin of the Korean Chemical Society
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• 제19권10호
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• pp.1047-1054
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• 1998

We present the results of molecular dynamics simulations for three different systems of bilayers of long-chain alkyl thiol [S(CH2)15CH3] molecules on an solid-solid interface using the extended collapsed atom model for the chain-molecule. It is found that there exist two possible transitions: a continuous transition characterized by a change in molecular interaction between sites of different chain molecules with increasing area per molecule and a sudden transition from an ordered lattice-like state to a liquid-like state due to the lack of interactions between sites of chain molecules on different surfaces with increasing distance between two solid surfaces. The third system displays a smooth change in probability distribution characterized by the increment of gauche structure in the near-tail part of the chain with increasing area per molecule. The analyses of energetic results and chain conformation results demonstrate the characteristic change of chain structure of each system.

• Bulletin of the Korean Chemical Society
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• 제13권6호
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• pp.613-620
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• 1992

The solvent-dependent photophysical properties of 2-biphenylcarboxylic acid (2BPCA) and 4-biphenylcarboxylic acid(4BPCA), which have a pre-twisted conformation in the ground state, have been investigated. The fluorescence spectra of 4BPCA show vibrational structure with a non-mirror image to the absorption spectra in nonpolar solvent while those of 2BPCA show no structure even in nonpolar solvents. As the solvent polarity increases, the fluorescence spectra become diffuse and broad with a strong red shift resulting in the large Stokes shift. The large fluorescence Stokes shift of BPCA's in polar solvent is also partially due to an intramolecular charge transfer (ICT) interaction in the excited state, as demonstrated by the large dipole moment in the excited state (7.6-10.6 D). The fluorescence decay behaviors of BPCA's (decay-times and their pre-exponential factors) also depend on solvent polarity in agreement with the solvent-dependent properties of the steady-state fluorecence. The data have been discussed in terms of change in the excited-state potential energy surface with respect to change of the dihedral angle of biphenyl moiety.

• 한국잠사곤충학회지
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• 제39권2호
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• pp.186-196
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• 1997

The IR crystallinity index of Calcium nitrate treated silk fiber decreased proportionally to the concentration of calcium nitrate. A partial change of conformation was observed in the concentration of over 46.4-47.6% changing from $\beta$-sheet or to random coil in the crystalline region. This is in coincidence with the result of crystallinity index, which was started to be reduced in the concentration range of 46.4-47.6%. A same trend was observed for the X-ray order factor, birefringence, degree of orientation and surface structure. These structural parameters were remarkably changed on the treatment of silk fibers with concentration of 46.4-17, 6% calcium nitrate. Therefore, it seems that there exists a critical concentration of calcium nitrate in affection the structure and morphology of silk fibers. According to the examination of surface morphology, the fine stripe was observed in the direction of fiber axis at 46.4% concentration. However, the treated concentration was exceeded by 47.6%, the cracks were appeared severely on the fiber surface in the transverse direction as well as fiber axis direction. This result might be related to the tensile properties, specially a tenacity of silk fibers. As a result of quantitative analysis of a dilute acid hydrolysis, three different regions, which are known as a amorphous, semi-crystalline and crystalline region, could be obtained. The hydrolysis rate curves were different with various concentrations of treatment and the relative contents of each region could be calculated.

• 한국인쇄학회지
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• 제14권1호
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• pp.47-54
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• 1996

Deuterium NMR studies have been carried out for two kinds of main- chain dimer liquid crystals $\alpha$.$\omega$-bis[(4,4`-cyanobipheny0oxy] alkane (CBA-n, n=9,100.The H-NMR spectra were recorded on a JEOP JNM-GSX-500 spectrometer by using deuterium labelled CBA-n at various temperatures. The RIS analysis of the NMR spectra was performed so as to elucidate the conformational characteristics of the spacer in the nematic phase. Following the previous treatment, the single-ordering-matrix model was adopted, in which the molecular axis was defined parallel to the line connecting the centers of the terminal mesogenic cores. Conformer fractions of the spacer were estimated by simulation so as to reproduce the observed NMR profile. The conformational entropy changes at both CN and NI interphases were estimated on the basis of the nematic conformations taken from the conformation map as well as those derived from the simulation. In these calculations the spacer was assumed th by in the all-trans conformation and in the random coil stats in the crystal and isotropic phases respectively. The esimated conformational entropy change values were then compared with the corresponding constant-volume entropies obtained from PVT measurements. The correspondence between both entropy values was found to be quite good in consideration of the uncertainties involved in both experiment and calculations.

• 약학회지
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• 제40권6호
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• pp.632-639
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• 1996

Most stable conformers of some antiinflammatory fenamates were obtained by conformational free energy change calculations. Conformational energies for the molecules as unhydrate d state were estimated first, and those as hydrated state were calculated then to simulate the molecules in aqueous solution using a hydration shell model. The initial geometries of the molecules were obtained either from X-ray crystallographic data or from homologous molecular fragments. The bond lengths and angles were not varied, but all the torsion angles were varied step by step during the conformational free energy surface searching. The results show that there are several feasible conformations for a compound. And the molecules are somewhat stabilized by hydration (-${\delta}G_{hyd}{\cong}$13 to 16kcal/mole), but the conformations were not changed significantly by the hydration itself. There seems to be a strong tendency of intramolecular hydrogen bonding between imino hydrogen and carboxyl oxygen of the compounds. As a result, the carboxyl group cannot be rotated freely, and the rotation of the second aromatic ring is the main reason for the conformational variations of the compounds. The ECEPP force fields via the program CONBIO were used throughout this study.

• 대한안전경영과학회지
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• 제4권2호
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• pp.71-81
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• 2002

Today's environment of enterprise is changing. They have to face customer' demands with the right product, the right service and supply them at the right time. And also cut down logistics and inventory cost and bring up the profit as much as they can. This means the change of putting enterprise first in importance to putting customer first importance. therefore to correspond to customer's demand, shorting lead time is becoming a essential condition. The answer to this changes of environment is supply chain management. In the Supply chain, The ATP function doesn't only give customers to conformation of delivery. It can be used by the core function with ATP rule that can reconcile supplies and demands on the supply chain. Therefore We can be acquire the conformation about on the due date of supplier by using the ATP function of management about real and concurrent access on the supply chain, also decide the affect about product availability due to forecasting or customer's orders through the ATP. In this paper, It consolidates the necessity on a CTP and analyzes data which is concerned of ATP. Under the these environments, defines the ATP rule that can improve the customer value and data flow related the LTV(Life Time Value) and builds on a algorithm.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2002년도 International Symposium on Magnetic Resonance
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• pp.90-90
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• 2002

Syndecans, transmembrane heparan sulfate proteoglycans, are coreceptors with integrin in cell adhesion process. It forms a ternary signaling complex with protein kinase C and phosphatidylinositol 4,5 bisphosphate (PIP2) for integrin signaling. NMR data indicates that cytoplasmic domain of syndecan-4 (4L) undergoes a conformational transition in the presence of PIP2, forming oligomeric conformation. The structure based on NMR data demonstrated that syndecan-4L itself forms a compact intertwined symmetric dimer with an unusual clamp shape for residues Leu$^{186}$ -Ala$^{195}$ . The molecular surface of the syndecan-4L dimer is highly positively charged. In addition, no inter-subunit NOEs in membrane proximal amino acid resides (Cl region) has been observed, demonstrating that the Cl region is mostly unstructured in syndecan-4L dimmer. However, the complex structure in the presence of PIP2 induced a high order multimeric conformation in solution. In addition, phosphorylation of cytoplasmic domain induces conformational change of syndecan-4, resulting inhibition of PKC signaling. The NMR structural data strongly suggest that PIP2 promotes oligomerization of syndecan-4 cytoplasmic domain for PKC activation and further induces structural reorganization of syndecan for mediating signaling network in cell adhesion procedure.

• Journal of Microbiology and Biotechnology
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• 제15권6호
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• pp.1392-1396
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• 2005

Proteolytic digestion and CD measurement of wild-type and mutant cyclic AMP receptor proteins (CRPs) were performed either in the presence or absence of cyclic nucleotide. Results indicated that transition of a structural change to the hinge region by the binding of cAMP to the anti site was required for the binding of cAMP to the syn site near the hinge region and, although the occupancy of cAMP in the anti site increased the protein stability, CRP adopted more a stable conformation by the binding of cAMP to the syn site.

• 통합자연과학논문집
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• 제4권3호
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• pp.222-226
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• 2011

Cyclic AMP receptor protein(CRP) is involved in the activation of many genes corresponding to catabolite enzymes in Escherichia coli. In this study, mutant CRP(S128A) was used to elucidate the effect of Ser 128 on the cAMP-induced structural change. Based on the protease digestion and thermal analysis, serine 128 in CRP affects the cAMP binding capability and then structural change of CRP protein. In addition, CD spectra in near UV region revealed that S128A CRP retained the sensitive conformation to thermal effect relative to that of wild-type CRP, in spite of identical Tm values in the absence of cAMP.