• Journal of Plant Biology
• /
• v.38 no.4
• /
• pp.359-364
• /
• 1995

As the first step to elucidate the relationship between the structure and function of CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15) in plants, the partial nucleotide sequence of soybean cytidylyltransferase cDNA was determined using a polymerase chain reaction (PCR). Degenerate oligonucleotide primers were synthesized from the conserved region revealed from the rat and yeast cytidylyltransferase DNA sequences. The catalytic domain region showed 78 and 76% homology with the rat and yeast amino acid sequences, respectivly. The hydropathy profile indicated that the C-terminal non-catalytic portion of the protein was very hydrophilic, and in the region between the catalytic domain and the C-terminal region, there was a large amphipathic $\alpha$-helical domain that was believed to bind the membrane surface in the active formation. There are 7 potential sites for phosphorylation by protein kinase C and 4 potential sites for phosphorylation by Ca2+/calmodulin kinase within the determined sequence.

• Proceedings of the Korean Biophysical Society Conference
• /
• 1996.07a
• /
• pp.33-33
• /
• 1996

An ectodomain of gp41, the transmembrane fusion protein of HIV, without the fusion peptide region was expressed using pET system in E. coli. The expressed protein gp41core, was isolated as inclusion body and was purified by ion-exchange chromatography after solubilized in 6M urea. The purified denatured protein was renaturated and the folded domain of gp41core was identified by the presence of the proteolysis resistence domain and a high content of ${\alpha}$-helical secondary structure. (omitted)

• YAKHAK HOEJI
• /
• v.54 no.1
• /
• pp.67-74
• /
• 2010

Some of the benzopyrene (BP)-DNA adduct are known to build intercalated motif between flanking base pairs in damaged DNA depending on the structural condition. The size of benzopyrene itself is definitely not comparable with any of the DNA bases and thus the question whether the lesion of some base pair by insertion of benzopyrene can happen with or without a dramatic distortion of the helical structure is a highly interesting theme. In this work we used a molecular dynamics simulation based on the theory of molecular mechanics. The specific consequences about the structural properties of the intercalated structures and benzopyrene motif in minor groove of the double helix are deduced after 5 ns simulation time.

• Journal of the Korean Magnetic Resonance Society
• /
• v.8 no.2
• /
• pp.96-107
• /
• 2004

We prepared two oligonucleotides containing same base pairing, but different base sequence in the middle region, d(CGAATTCG) and d(CGTATACG). NMR and UV absorbance data represented that such variation in base sequence could cause a significant difference in melting temperature and dynamics between d(CGAATTCG)$_2$ and d(CGTATACG)$_2$ duplexes, which are regarded to be associated with the stacked structure and the width of the minor groove of them. The latter showed poor stability compared to the former, because of poor stacking of bases. And berenil could bind to the minor groove of d(CGAATTCG)$_2$ which is relatively narrow, more strongly than d(CGTATACG)$_2$ and this gave rise to large improvement in thermal stability of the d(CGAATTCG)$_2$ duplex, compared to d(CGTATACG)$_2$.

• Bulletin of the Korean Chemical Society
• /
• v.20 no.9
• /
• pp.1073-1077
• /
• 1999

CRAMP, a 37-amino acid cationic antimicrobial peptide was recently deduced from the cDNA cloned from mouse femoral marrow RNA. In order to investigate the structure-activity relationship and functional region of CRAMP, CRAMP and its 18-mer overlapping peptides were synthesized by the solid phase method. CRAMP showed broad spectrum antibacterial activity against both Gram-positive and Gram-negative bacterial strains (MIC: 3.125-6.25 μM) but had no hemolytic activity until 50 μM. CRAMP was found to have a potent anticancer activity (IC50: 12-23 μM) against two human small cell lung cancer cell lines. Furthermore, CRAMP was found to display faster bactericidal rate in B. subtilis rather than E. coli in the kinetics of bacterial killing. Among 18-meric overlapping fragment peptides, only CRAMP (16-33) displayed potent antibacterial activity (MIC: 12.5-50 μM) against several bacteria with no hemolytic activity. Circular dichroism (CD) spectra anal-ysis indicated that CRAMP and its analogues will form the amphipathic α-helical conformation in the cell membranes similar to other antimicrobial peptides, such as cecropins and magainins.

• Journal of the Korean Society of Visualization
• /
• v.18 no.3
• /
• pp.90-95
• /
• 2020

The purpose of this study is to numerically evaluate the collection performance of an ultra-small Lapple cyclone separator for 1~10 ㎛ particles introduced at flow rate of 10 L/min. The numerical evaluation reveals that a static pressure drop occurs more dominantly inside of the cyclone separator than at the inlet and the vortex finder. Also a fluid flow in the cyclone separator is confirmed to have a helical structure heading upward in the center of cyclone separator and downward in the vicinity of wall. The investigation on dust collection efficiency of the Lapple cyclone separator shows that particles of 4~8 ㎛ diameters are collected at very lower efficiency than other sizes. Then, the cut-point diameter of the cyclone separator is 1.48 ㎛.

• Bulletin of the Korean Chemical Society
• /
• v.17 no.3
• /
• pp.239-244
• /
• 1996

Mastoparan B (MP-B) that is a novel MP isolated from the hornet Vespa basalis, was studied as compared with MP, in terms of interaction with phospholipid bilayer and antimicrobial activity. MP-B has more hydrophilic amino acid residues in hydrophilic face of amphiphilic α-helical structure than MP. The both peptides exhibited considerably different effect on interaction with lipid bilayers, e.g. their conformation in the presence of acidic and neutral liposomes, dye-release ability from encapsulated liposomes, but on the whole the interaction mode was similar. On antimicrobial activity, MP had a strong activity against Gram-positive bacteria but no against Gram negative ones. Contrary to this, MP-B had a strong activity against Gram-positive and potent against Gram-negative ones. Since both peptides have almost same residues on the hydrophobic side, such more hydrophilic surface on the molecule seems to lead to the subtle change in its interaction with membranes, resulting in the alternation in its biological activity.

• Molecules and Cells
• /
• v.25 no.1
• /
• pp.138-141
• /
• 2008

HP0892 (SwissProt/TrEMBL ID O25552) is a 90-residue conserved hypothetical protein from Helicobacter pylori strain 26695, with a calculated pI of 9.38 and a molecular mass of 10.41 kDa. It belongs to the Plasmid stabilization system protein family (PF05016) in the Pfam database. Proteins with sequence similarity to HP0892 exist in Vibrio choierae, Enterococcus faecalis, Campylobacter jejuni, Streptococcus pneumoniae, Haemophilus influenzae, Escherichia coli O157. Here we report the sequence-specific backbone resonance assignments of HP0892 using multidimentional heteronuclear NMR spectroscopy. About 97.0% (422/435) of the HN, N, CO, $C{\beta}$, $C{\alpha}$ resonances of 90 residues of HP0892 were assigned. On the basis of the resonance assignments, three helical regions and four strand regions were identified using the CSI program. This study is a prerequisite for calculating the solution structure of HP0892, and will be useful for studying its interaction with other molecules.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.46 no.7
• /
• pp.567-574
• /
• 2018

Swirl injection induces not only the increase in fuel regression rate but also the reduction of combustion pressure oscillation. This acts, in turn, to stabilize combustion process. Thus, this study primarily focuses on the change in flow structure in the main chamber by swirl injection. Then examining the change in flow structure was done to understand the physical process for stabilizing combustion. In the results, the application of swirl injection could suppress the generation of p' and q' in 500Hz band and could shift the phase difference and cross correlation. Further investigations with combustion visualization also show that the development of helical motion near surface region affects the small-sized vortex generation and shedding yielding combustion stabilization eventually.

• Journal of the Korean Magnetic Resonance Society
• /
• v.11 no.2
• /
• pp.129-137
• /
• 2007

During the screening of material which has the antimicrobial activity against aminoglycoside-resistant bacteria, A new material ${\varepsilon}-(L-{\beta}-lysine)$ polypeptide from a culture medium of Streptomyces sp.(DWGS2) was isolated, and the structure and the physicochemical properties of the new material were elucidated. The new material was separated by column chromatography of the culture medium using Dowex $1{\times}2$, Silica gel, and Sephadex LH20 etc. The structure and molecular weight were determined with the data of NMR, MALDI mass, and ESI mass experiments. And the monomer obtained by hydrolysis of the new material with 6N-HCI was identified as a $L-{\beta}-lysine(T_2)$, which is a tail of bleomycin. As tail-region analogy, $T_2({\beta}-lysine$ derivatives from streptomyces) interactions with a self-complementary oligonucleotides, $d(CGCTTCGAAGCG)_2$, was investigated by NMR.