• YAKHAK HOEJI
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• v.53 no.4
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• pp.228-234
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• 2009

Topoisomerase I (Topo I) participates in the DNA replication, transcription, and repair. Binding of Topo I inhibitor to the Topo I-DNA cleavage complex forms stabilized ternary complex which blocks DNA religation and ultimately causes cell death. Camptothecin (CPT) and its derivatives have been among the most effective anticancer drugs by inhibition of topo I. However, efforts to synthesize non-CPT drugs have been actively going on because the CPT derivatives have several limitations such as poor solubility, short half-life, and side effects. As an indenoisoquinoline, NSC314622 is not as potent as CPT, but its chemical stability and slower reversibility of the cleavage complex made it a good lead compound. Recently, a series of indenoisoquinoline analogues were synthesized with substituted dimethoxy or methylenedioxy on the aromatic ring and alkylamino on the lactam nitrogen. Some of them showed quite good Topo I inhibitory activity. Using the computer docking program, Surflex-Dock, indenoisoquinoline analogues were docked into the human Topo I-DNA cleavable complex. The docking results showed that the compounds with activity better than NSC314622 intercalated between the -1 and +1 base pairs at the cleavage site, but those with little or no activities did not appear to intercalate. These results could be useful to design new Topo I inhibitors improved than CPT.

• Journal of Microbiology and Biotechnology
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• v.8 no.3
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• pp.264-269
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• 1998

Commamonas acidovorans SMN4 showed wide growth substrate spectra for various aromatic hydrocarbons. Strain SMN4 was able to grow on biphenyl producing a meta-cleavage compound, yellow 2-hydroxy-6-oxophenylhexa-2,4-dienoic acid with a spray of 2,3-dihydroxybiphenyl, while it also grew on catechol, developing yellow 2- hydroxymucoic semialdehyde with a spray of 100 mM catechol. Thus these results indicate that two-ring structures of biphenyl were cleaved by meta-mode in upper and lower pathways. Strain SMN4 metabolized various substituted biphenyl compounds and xylene to the corresponding benzoate derivatives through oxidation of the ring structures. It was clearly shown that biphenyl can be a common inducer in the oxidation of biphenyl and 2,3-dihydroxybiphenyl. Various compounds were examined for their suitability to serve as substrates for indole oxidation, indicating that biphenyl, benzoate, and succinate are quite good inducers of indigo production due to the activity of biphenyl dioxygenase. This results suggest that indigo formation is by means of the combined activities of biphenyl dioxygenase and tryptophanase.

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.484-489
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• 1990

An intracellular inulase ( fJ-fructofuranoside fructohydrolase, EC 3.2.1.26) from Bacillus subtilis has been partially purified and its mode of action and general properties were studied. The enzyme had an apparent molecular weight of 49,000 as estimated by gel filtration and its pI point was 5.2. Substrate concentration studies showed an apparent Km of 10 mM for sucrose and of 18 mM for raffinose. The enzyme was an acid-labile protein with a pH optimum of 6.6. The optimum temperature was 50$^{\circ}$C. The enzyme acts on straight chain oligo- and poly-fructosides of the inulin series via a exo-wise cleavage mechanism, as well as on sucrose.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1547-1552
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• 2022

β-Amyrin is a pentacyclic triterpene widely distributed in leaves and stems worldwide. The ability of β-amyrin to induce the production of reactive oxygen species (ROS) in microorganisms suggests its potential as an antimicrobial agent. Thus, this study aimed to elucidate the antibacterial mode of action of β-amyrin. We treated Escherichia coli cells with β-amyrin and found that it triggered ROS accumulation. Excessive stress caused by ROS, particularly hydroxyl radicals, induces glutathione (GSH) dysfunction. GSH protects cells from oxidative and osmotic stresses; thus, its dysfunction leads to membrane depolarization. The resultant change in membrane potential leads to the release of apoptotic proteins, such as caspases. The activated caspases-like protein promotes the cleavage of DNA into single strands, which is a hallmark of apoptosis-like death in bacteria. Apoptotic cells usually undergo events such as DNA fragmentation and phosphatidylserine exposure, differentiating them from necrotic cells, and the cells treated with β-amyrin in this study were positive for annexin V and negative for propidium iodide, indicating apoptosis-like death. In conclusion, our findings suggest that the antibacterial mode of action of β-amyrin involves the induction of ROS, which resulted in apoptosis-like death in E. coli.

• Microbiology and Biotechnology Letters
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• v.22 no.4
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• pp.360-367
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• 1994

The effect of various nutrients for the production of the anti-complementary polysaccha- ride by Flammulina velutipes, was examined and the partial purification of the polysaccharide was carried out. The culture conditions and medium compositions considerably influenced the anti-complementary activity of the polysaccharides. When a culture was carried out at 23$\circ$C and pH 5.5 for 6 days in the synthetic medium supplemented with galactose and NaNO$_{3}$, the production of the anti-complementary polysaccharide was maximized. The crude polysaccharide, FV-1 was isolated from the culture broth and partially purified into two fractions, FV-1-II and FV-1-III by gel filtration using Sephadex G-100. FV-1-II was mainly consisted of xylose, mannose, galactose and glucose, and rhamnose, mannose and galactose, for FV-1-III. Also, the anti-complementary activity of FV-1-III was reduced partially in the absence of the Ca ion. When crossed immunoelect- rophoresis using anti-human C3 serum was carried out after incubation of normal human serum with the FV-1-III in the Ca ion free condition, a cleavage of C3 precipitin line was observed. These results indicate that the mode of complement activation by polysaccharide from Flammulina velutipes is via not only the classical pathway but also the alternative pathway.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1339-1345
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• 2018

2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase, which catalyzes aldol cleavage and condensation reactions, has two distinct substrate-binding sites. The substrate-binding mode at the catalytic site and Schiff-base formation have been well studied. However, structural information on the phosphate-binding loop (P-loop) is limited. Zymomonas mobilis KDPG aldolase is one of the aldolases with a wide substrate spectrum. Its structure in complex with the substrate-mimicking 3-phosphoglycerate (3PG) shows that the phosphate moiety of 3PG interacts with the P-loop and a nearby conserved serine residue. 3PG-binding to the P-loop replaces water molecules aligned from the P-loop to the catalytic site, as observed in the apostructure. The extra electron density near the P-loop and comparison with other aldolases suggest the diversity and flexibility of the serine-containing loop among KDPG aldolases. These structural data may help to understand the substrate-binding mode and the broad substrate specificity of the Zymomonas KDPG aldolase.

• Bulletin of the Korean Chemical Society
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• v.23 no.11
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• pp.1604-1610
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• 2002

In the present work, we studied thiram on silver surface by SERS. Investigations of disulfides with SERS revealed that the molecules undergo a surface reaction on silver, namely easy cleavage of the S-S bond. We believe that the two S atoms of resonance formed from the thiram may be chemisorbed strongly on Ag sol. This resonance form adheres perpendicularly to the Ag surface via the two S atoms, since the ${\delta}(CH3)$ and n (CN) mode perpendicular to the surface showed strong enhancement. The important roles of halide anion adsorption have been discussed and the pH effects of thiram on Ag sol in acidic, neutral, and alkaline conditions were examined.

• The Korean Journal of Food And Nutrition
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• v.9 no.4
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• pp.490-495
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• 1996

The anti-compliment activity of hemolytic complementary assay(TCH50) of rhamnan sulfate fraction obtained from water extracts of Monostroma nitidum was investigated Rhamnan sulfate Fraction, F-4-3 fraction appeared relatively strong anti-complementary activity which decreased TCH50 over 60% than that comparison with control, and F-4-3 considerably inhibited ACH50. F-4-3 inhibited formation of the classical pathway C3 convertase or C4 cleavage. The results also indicate the mode of complement activation by F-4-3 fraction shows not only the classical pathway but also the alternative pathway.

• Journal of the Korean Magnetic Resonance Society
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• v.27 no.2
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• pp.5-9
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• 2023

t ENOD40B, a plant peptide hormone, was doubly labeled with C-13 and N-15 by recombinant production in Escherichia coli. The peptide was prepared by affinity chromatography followed by protease cleavage and reverse-phase chromatography. To elucidate the mode of action against its receptor, sucrose synthase, we proceeded to assign the backbone and side-chain resonances using a set of double and triple resonance experiments. This result will be used to determine the three-dimensional structure of the peptide at its bound state as well as to observe the chemical shift changes upon binding.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.6
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• pp.269-275
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• 2005

Ni/Ni-aluminide/Ti/Ti-aluminide laminate composite, considered as a functionally gradient material, was manufactured by thin foil hot press technique. Thick intermetallic layers of NiAl and $TiAl_3$ were formed by a self-propagating high-temperature synthesis (SHS) reaction, and thin continuous taters of $Ni_3Al$ and TiAl were formed by a solid-state diffusion. Fracture resistance with loading along the crack arrester direction is higher than crack divider direction due to the interruption of crack growth in metal layers. The $Ni_3Al$ and NiAl intermetallic layer showed cleavage and intergranular fracture behavior, respectively, while the fracture mode of $TiAl_3$ layer was found to be an intragranular cleavage. The debonding between metal and intermetallic layer and the pores were observed in the Ni/Ni-aluminide layers, resulting in the lower fracture resistance. With the results of acoustic emission (AE) source characterization the real time of failure and the effect of AE to crack growth could be monitored.