• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1170-1176
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• 2005

The structures and conformations of ortho-, meta-, and para-methyl red (MR) upon proton gain and loss were studied by density functional calculations, and compared to methyl yellow for the effects of a carboxyl substitution. Internal hydrogen bonding causes the geometry of neutral o-MR planar, otherwise twist. Monoprotonated species of MR are planar where the proton is attached to $\beta$-azo nitrogen. This loses its azo character a bit, and shows strong delocalization characterized as a quinonoid canonical structure. Di-protonated species of MR is proved to hold two protons at the amino and $\alpha$-azo nitrogen atoms, and planar. It regains somewhat of its azo character, but still shows fairly delocalized property in terms of carbocationic canonical structures. The carboxyl substitution on 4-dimethylamino-trans-azobenzene structure has some delocalization effects on the geometry or conformation of MR derivatives whether neutral, mono-, di- or de-protonated.

• Journal of Applied Biological Chemistry
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• 제43권1호
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• pp.37-43
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• 2000

1,3,2-Dioxaphosphorinanes are suitable compounds for studying the stereochemistry of substitution at phosphorus. Cis- and trans-5-hydroxymethl-5-methyl-2-thiono-2ethoxy-1,3,2-dioxaphosphorinane were prepared, and their structures and stereochemistry unambiguously assigned by NMR and X-ray crystallography with acetoxy and 3,5-dinitrobenzoyloxy derivatives, respectively. Trans isomer gave $^{31}P$ NMR signal at higher field than cis isomer, and the ring proton Spectrum of cis isomer showed characteristic pattern for identifying its geometry. In X-ray crystallography they adopted a chair conformation with the ethoxy groups in the axial positions, and the sulfide groups in the equatorial positions. A flattening of the ring around the phosphorus center was noted, the POC bond angles were about $120^{\circ}$, and the C-O bonds in the ring were significantly longer than the C-O bond for the ethoxy group or the C-O bond for hydroxyl group.

• 한국잠사곤충학회지
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• 제44권2호
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• pp.87-92
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• 2002

염화아연에 의한 작잠 견사의 용해 조건을 살펴본 후 투석법에 의하여 얻은 작잠 견피브로인 분말의 형태와 적외선 분광 특성 및 X-선 회절 특성을 살펴본 결과 다음과 같은 결론을 얻었다. 1. 작잠 견사는 고농도의 염화아연 수용액에 용해되었으나 용해 조건을 조절하여 완전하게 작잠 견사를 용해할 수 있었다. 2. 재생 작잠 분말의 구조 특성을 살펴보기 위하여 적외선 분광분석과 X-선 회절분석을 행한 결과 작잠분말은 $\beta$-sheet 구조와 $\alpha$-helix 구조로 이루어져 있었다. 3. 염화아연을 사용하여 제조한 작잠 견피브로인 용액으로부터 순수한 작잠 견피브로인을 얻기 위한 새로운 방법이 개발되어야 함을 알 수 있었다.

• 한국자기공명학회논문지
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• 제17권2호
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• pp.81-85
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• 2013

Various fluorine-containing materials are used in electronic devices like LCD display panels and Li-ion batteries. The structural conformation of fluorine in fluorinated materials is an important contributing factor that influences the chemical and physical properties. The conformation can be changed by heat and stress during manufacture or use. Understanding the conformational changes is critical for understanding the performance and durability of electronic devices. Solid-state NMR spectroscopy could be widely used for the analysis of various fluorine-containing materials for electronic devices. However, conventional CPMAS probes cannot be used for in-situ analysis of fluorine-containing electronic devices like LCD panels and Li-ion batteries. In this paper, we show the design, construction, and optimization of a $^{19}F-^{13}C$ double-resonance solid-state NMR probe for a 400MHz wide-bore magnet with a flat square coil for in-situ analysis of fluorine-containing electronic devices without observing fluorine background signals. This custom-built probe does not show any fluorine background signals, and can have higher efficiency for lossy samples.

• 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.

• 한국잠사곤충학회지
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• 제42권2호
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• pp.114-119
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• 2000

Effects of ethanlo treatment on the structural and thermal characteristics of regenerated Antheraea pernyi silk fibroin (RSF) were investigated. Infrared spectroscopy and X-ray diffractometry showed that the conformational transition of RSF might be affected by concentration of ethanol and its treatment time. The structure of RSF was rapidly changed from random coil to $\beta$-sheet conformation when RSF was treated with les than 75% ethanol concentration. However, RSF treated with ethanol(100%) did not show conformational change. Differential scanning calorimetry showed that exotherm at 232$\^{C}$ disappeared and the intensity of endotherm at 228$\^{C}$ decreased with treatment of 75% ethanol. Dynamic thermal analysis showed that loss modulus (E") and tan $\delta$$\_$E/ of RSF treated with aqueous ethanol was broaden and shifted to higher temperature in comparison with those of untreated RSF.

• Journal of Oral Medicine and Pain
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• 제23권3호
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• pp.241-247
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• 1998

Salivary research is at a critical crossroads regarding the clinical application of the basic knowledge. The purpose of this article is to introduce the current progress on salivary research to Korean dental scientists. The accumulated results based on advance technologies such as protein chemistry, molecular biology, and structural biology have showed that salivary macromolecules need structural requirements for proper function. Currently, several concepts or principles, which can be applied to salivary macromolecules, have been suggested. These include the role of molecules' conformation on biological activity, their multifunctional nature, their redundancy of function, their amphifunctional properties, and the potential importance of complexing between molecules. These concepts and the information available will help the development of saliva substitutes, the design of drug carriers and chimera molecules with enhanced function and the development of gene therapy protocols. These approaches will alleviate or restore lost salivary function and can be used to treat various kinds of oral and systemic diseases.

• 한국자기공명학회논문지
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• 제23권3호
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• pp.67-72
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• 2019

Caveolae are small plasma membrane invaginations that play many roles in signal transduction, endocytosis, mechanoprotection, lipid metabolism. The most important protein in caveolae is the integral membrane protein, caveolin, which is divided into three families such as caveolin 1, caveolin 2, and caveolin 3. Caveolin 1 and 3 are known to incorporate palmitate through linkage to three cysteine residues. Regulation of the protein palmitoylation cycle is important for the cellular processes such as intracellular localization of the target protein, membrane association, conformation, protein-protein interaction, and activity. However, the detailed aspect of individual palmitoylation has not been studied. In the present work, the role of each lipid modification at three cysteines was studied by NMR. Our results suggest that each lipid modification at the natively palmitoylation site has its own roles. For example, lipidations to C106 and C129 are play a role in structural stabilization, however, interestingly, lipid modification to C116 interrupts the structural stabilization.

• 한국자기공명학회논문지
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• 제5권1호
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• pp.46-55
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• 2001

P23, a translationally controlled turner protein is involved in the interleukin-4 secretion from human basophils and is also known to be an IgE-dependent histamine-releasing factor. However, the precise physiological function and structure of P23 have not been elucidated. In the current study, we constructed the optimal expression and purification protocol of P23 and investigated the secondary structure and structural stability in various conditions. Circular dichroism (CD) investigation showed that the secondary structure of P23 adopts mainly a P-sheet conformation. CD spectroscopy and differential scanning calorimetry revealed that P23 is fairly stable in the pH range of neutral and mild-basic conditions and in the temperature range of 10 - 50$\^{C}$. Since the thermal stability and the P-sheet content of P23 were decreased by the addition of Ca$\^$2+/ ion, it could be suggested that Ca$\^$2+/ion induces structural change by partially destabilizing the structure of P23. In addition various H experiments were monitored to solve the aggregation of P23. Den results will provide the preliminary structural information about P23.