• Journal of the Korean Chemical Society
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• v.22 no.2
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• pp.55-61
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• 1978

MO theoretical studies on the conformations of N-acetylpyrrolidone and its protonated form were carried out by the EHT and CNDO/2 methods. According to our calculated results, the heavy atom skeleton of this molecule is planar, and the trans-trans planar conformation is more stable than cis-trans. The protonation occurs most readily on the ring carbonyl oxygen. These results were interpreted in terms of conjugative, electrostatic and steric effect.

• BMB Reports
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• v.37 no.6
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• pp.676-683
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• 2004

The conformational properties of hydrophobic core variant ubiquitin (Val26 to Ala mutation) in an acidic solution were studied. The intrinsic tryptophan fluorescence emission spectrum, far-UV and near-UV circular dichroic spectra, the fluorescence emission spectrum of 8-anilinonaphthalene-1-sulfonic acid in the presence of V26A ubiquitin, and urea-induced unfolding measurements indicate this variant ubiquitin to be in the partially folded molten globule conformation in solution at pH 2. The folding kinetics from molten globule to the native state was nearly identical to those from the unfolded state to the native state. This observation suggests that the equilibrium molten globule state of hydrophobic core variant ubiquitin is an on-pathway folding intermediate.

• Applied Microscopy
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• v.19 no.2
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• pp.59-73
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• 1989

To investigate the effect of cadmium and cadmium binding protein on the electron transport system and conformational changes of rat kidney mitochondria, various cadmium concentration were treated in vitro and respiration rate, NADH-CoQ reductase activity were measured. Ultrastructural changes at state IV respiration were also observed. CdBP was isolated from the rat liver by Sephadex G-75 column fractionation and treated in vitro with cadmium. Also mitochondrial state IV respiration rate was measured. When cadmium was treated in vitro, state IV respiration and enzyme activity were decreased and ultrastructural transformation of mitochondria from a condensed to an orthodox conformation was inhibited under state IV respiration. In case cadmium and CdBP were treated together, oxygen consumption was more increased than cadmium only. Conformational changes of mitochondria from a condensed to orthodox conformation were also observed. This indicates that CdBP have a protective effect against cadmium toxicity.

• Bulletin of the Korean Chemical Society
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• v.30 no.10
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• pp.2341-2344
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• 2009

Metallacyclodimers, [Ag(OTf)($L1)]_2$ and [Ag($L2)]_2(OTf)_2$ (L1 = 1,3-dibromo-2,2-bis[(isonicotinoyloxy)methyl] propane; L2 = 2,5-dimethyl-2,5-bis(isonicotinoyloxy)hexane) were constructed and characterized. The crystal structure of [Ag(OTf)($L1)]_2$ reveals a 32-membered cyclodimer, whereas that of [Ag($L2)]_2(OTf)_2$ shows a linked 34-membered cyclodimer chain via intercyclic argentophilic (Ag…Ag) interactions. [Ag(OTf)($(L1)]_2$ affords “intramolecular $\pi-\pi$ interaction cyclodimer” whereas [Ag($L2)]_2(OTf)_2$ produces a racemic mixture of “twisted cyclodimer”. Ring-conformation of the cyclodimers was affected via the competition of electrostatic interaction and argentophilic interaction.

• Journal of the Korean Chemical Society
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• v.20 no.6
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• pp.507-513
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• 1976

Conformation of cis-2-butenedialdioxime, a newly synthesized compound, was assigned by means of nuclearmagnetic resonance, extended Huckel molecular orbital method, and Pople's model of anisotropic effect. It was confirmed that two carbon-carbon single bonds are conrotatorily twisted from the molecular plane of six $sp^2$ orbitals of carbon-carbon double bond. The conformation of minimum energy is found to be twisted by$25^{\circ}C.$

• Proceedings of the Botanical Society of Korea Conference
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• 1998.07a
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• pp.83-96
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• 1998

The plant pigment proteins phytochromes are a molecular light sensor or switch for photomorphogenesis involving a variety of growth and developmental responses of plants to red and far-red wavelength light. Underscoring the photomorphogenesis mediated by phytochromes is the light signal transduction at molecular and cellular levels. For example, a number of genes activated by the phytochrome-mediated signal transduction cascade have been identified and characterized, especially in Arabidopsis thaliana. The light sensor/switch function of phytochromes are based on photochromism of the covalently linked tetrapyrrole chromophore between the two photoreversible forms, Pr and Pfr. The photochromism of phytochromes involves photoisomerization of the tetrapyrrole chromophore. The "photosensor" Pr-form ("switch off" conformation) of phytochromes strongly absorbs 660 nm red light, whereas the "switch on" Pfr-conformation preferentially absorbs 730 nm far-red light. The latter is generally considered to be responsible for eliciting transduction cascades of the red light signal for various responses of plants to red light including positive or negative expression of light-responsive genes in plant nuclei and chloroplasts. In this paper, we discuss the structure-function of phytochromes in plant growth and development, with a few examples of biotechnological implications.

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.531-538
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• 2014

The quantum mechanical properties of a series of oligo-para-phenylenes (2-11) were characterized using DFT B3LYP/6-311G(d,p) calculations. The global minimum among the various torsional conformers of an oligo-p-phenylene is calculated to be a twist conformation. A less stable planar conformation, in which all the dihedral angles in oligo-p-phenylene are restricted to be planar, has also been calculated. The total electronic energies, normal vibrational modes, Gibbs free energies, and HOMOs and LUMOs of the two different conformations (twisted and planar) of the oligo-p-phenylenes were analyzed. The energy differences between the HOMOs and LUMOs of the substrates are in accord with the maximum absorption peaks of the experimental UV spectra of 2-6. The calculated normal vibrational modes of 2-6 were comparable with their experimental IR spectra.

• Journal of the Korean Chemical Society
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• v.52 no.6
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• pp.630-636
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• 2008

• Proceedings of the Korean Biophysical Society Conference
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• 1996.07a
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• pp.28-28
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• 1996

NMR studies on the structure of the luteinizing hormone releasing hormone (LHRH) in aqueous buffer and trifluoroethanol (TFE)/aqueous buffer (1:1, v/v) solution were performed. The NMR data under these conditions suggested a unique conformation which includes a ${\beta}$-1 turn of the Tyr5-Arg8 segment and an unusual turn of Ser4-Gly6 segment staggered with the ${\beta}$-I turn. (omitted)

• Bulletin of the Korean Chemical Society
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• v.24 no.10
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• pp.1470-1474
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• 2003

The dynamics of the tertiary conformation of myoglobin (Mb) after photolysis of carbon monoxide was investigated at 283 K solution by probing amide I and II bands using femtosecond IR absorption spectroscopy. Time-resolved spectra in the amide region evolve with 6-12 ps time scale without noticeable subpicosecond dynamics. The spectra measured at 100 ps delay after photolysis is similar to the difference FTIR spectrum at equilibrium. Time-resolved spectra of photoexcited Mb evolve modestly and their amplitudes are less than 8% of those of photolyzed MbCO, indicating that thermal contribution to the spectral evolution in the amide region is negligible. These observations suggest that the conformational relaxation ensuing photolysis of MbCO be complex and the final deoxy protein conformation have been substantially formed by 100 ps, probably with 6- 12 ps time constant.