• BMB Reports
• /
• v.28 no.2
• /
• pp.155-161
• /
• 1995

A nicotinic acetylcholine receptor (nAchR) isolated from the electric tissues of Torpedo californica has been reconstituted into a vesicle comprising a bifunctional azo-ligand (Bae 1) compound, and a liposome containing phospholipids and cholesterol (1 : 1, w/w). The liposome-mediated reconstituted receptor showed a concentration-dependent response to cholinergic drugs in a lithium ion flux assay. This liposome-mediated reconstituted nAchR was immobilized onto an electrode using various synthetic polymers which were tested for their response to the cholinergic ligands. The immobilized nAchR not only exhibited a linear response to a wide range of cholinergic ligand concentrations but also retained an operational stability which lasted for longer than 6 days. Thus, this result provides a basis for application of the immobilized nAchR-based biosensor in detecting cholinergic ligands in vitro.

• BMB Reports
• /
• v.38 no.6
• /
• pp.676-682
• /
• 2005

To date, no 8-oxoguanine-specific endonuclease-coding gene has been identified in Thermotoga maritima of the order Thermotogales, although its entire genome has been deciphered. However, the hypothetical protein Tm1821 from T. maritima, has a helix-hairpin-helix motif that is considered to be important for DNA binding and catalytic activity. Here, Tm1821 was overexpressed in Escherichia coli and purified using Ni-NTA affinity chromatography, protease digestion, and gel filtration. Tm1821 protein was found to efficiently cleave an oligonucleotide duplex containing 8-oxoguanine, but Tm1821 had little effect on other substrates containing modified bases. Moreover, Tm1821 strongly preferred DNA duplexes containing an 8-oxoguanine:C pair among oligonucleotide duplexes containing 8-oxoguanine paired with four different bases (A, C, G, or T). Furthermore, Tm1821 showed AP lyase activity and Schiff base formation with 8-oxoguanine in the presence of $NaBH_4$, which suggests that it is a bifunctional DNA glycosylase. Tm1821 protein shares unique conserved amino acids and substrate specificity with an 8-oxoguanine DNA glycosylase from the hyperthermophilic archaeon. Thus, the DNA recognition and catalytic mechanisms of Tm1821 protein are likely to be similar to archaeal repair protein, although T. maritima is an eubacterium.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.133-133
• /
• 2013

For both oxygen reduction (ORR) and hydrogen oxidation reactions (HOR) of proton electrolyte membrane fuel cells (PEMFCs), alloying Pt with another transition metal usually results in a higher activity relative to pure Pt, mainly due to electronic modification of Pt and bifunctional behaviour of alloy surface for ORR and HOR, respectively. However, activity and stability are closely related to the preparation of alloy nanoparticles. Preparation conditions of alloy nanoparticles have strong influence on surface composition, oxidation state, nanoparticle size, shape, and contamination, which result from a large difference in redox priority of metal precursors, intrinsic properties of metals, increasedreactivity of nanocrystallites, and interactions with constituents for the synthesis such as solvent, stabilizer, and reducing agent, etc. Carbon-supported Pt-Ni alloy nanoparticles were prepared by the borohydride reduction method in anhydrous solvent. Pt-Ru alloy nanoparticles supported on carbon black were also prepared by the similar synthetic method to that of Pt-Ni. Since electrocatalytic reactions are strongly dependent on the surface structure of metal catalysts, the atom-leveled design of the surface structure plays a significant role in a high catalytic activity and the utilization of electrocatalysts. Therefore, surface-modified electrocatalysts have attracted much attention due to their unique structure and new electronic and electrocatalytic properties. The carbon-supported Au and Pd nanoparticles were adapted as the substrate and the successive reduction process was used for depositing Pt and PtM (M=Ru, Pd, and Rh) bimetallic elements on the surface of Au and Pd nanoparticles. Distinct features of the overlayers for electrocatalytic activities including methanol oxidation, formic acid oxidation, and oxygen reduction were investigated.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.1
• /
• pp.187-192
• /
• 2010

In order to monitor the possibility of horizontal gene transfer between transgenic rice and microorganisms in a paddy rice field, the gene flow from a bifunctional fusion (TPSP) rice containing trehalose-6-phosphate synthase and phosphatase to microorganisms in soils was investigated. The soil samples collected from the paddy rice field during June 2004 to March 2006 were investigated by multiplex PCR, Southern hybridization, and amplified fragment length polymorphism (AFLP). The TPSP gene from soil genomic DNAs was not detected by PCR. Soil genomic DNAs did not show homologies on the Southern blotting data, indicating that gene transfer did not occur during the last two years in the paddy rice field. In addition, the AFLP band patterns produced by soil genomic DNAs from both transgenic and non-transgenic rice fields appeared similar to each other when analyzed by the NTSYSpc program. Thus, these data suggest that transgenic rice does not give a significant impact on the communities of soil microorganisms, although long-term observation may be needed.

• YAKHAK HOEJI
• /
• v.32 no.4
• /
• pp.239-244
• /
• 1988

Transcriptional rate of lactate dehydrogenase A-gene(LDH-A) during the prereplicative phase of regenerating rat liver was determined by in vitro run-off transcription assay. The results show that the transcription rate of LDH A-gene increases between 12 hours and 15 hours peaking at 13 hours after partial hepatectomy of rat liver. The increased rate of LDH A-gene transcription was interfered after DL-propranolol treatment intraperitoneally injected twice at 1 hour and 8 hours after partial hepatectomy indicating that the transcriptional control of LDH A-gene expression may be mediated by beta adrenergic receptor and cAMP as a second messenger. And also was it shown that the temporally increased rate of LDH A-gene transcription was maximum one hour after the second cAMP-surge which is known to play an important role for the initiation of DNA replication during regeneration of rat liver. And the transcriptional rate of LDH A-gene was decreased to the basal level at the time period when the hepatocytes proliferate rapidly suggesting that the induced LDH Aisozyme may be required for the initiation of DNA replication during regeneration of rat liver. These data may be supporting for the hypothesis suggesting that the induced LDH A-isozyme during the pre-replicative phase of regenerating rat liver may play bifunctional roles as a glycolytic enzyme and a helix destablizing protein as well.

• Carbon letters
• /
• v.10 no.3
• /
• pp.190-197
• /
• 2009

Various silanes, amino silane, vinyl silane, sulfur silane (TESPD), and ZS (TESPD/zinc soap complex), are added into chlorinated isobutylene-isoprene copolymer (CIIR)/soft clay/carbon black (CB) and CIIR/hard clay/CB compounds and they are investigated with respect to the vulcanization characteristics, the processability, and the mechanical properties. Comparing hard clay and soft clay filled compounds, hard clay (Suprex) filled system shows a higher die C tear than the soft clay (GK) filled one. The other properties (Mooney, extrusion torque/pressure, torque rise ($M_H-M_L$), modulus at 300%) are close to each other. Among various silanes, the ZS treated hard clay (Suprex) compound shows the highest mechanical property following hard clay(S)/vinyl silane(V) and soft clay(GK)/vinyl silane(V) compounds. The TESPD and the ZS effectively helps a formation of a strong 3-dimensional network structure between silica and CIIR via coupling reaction due to bifunctional nature of TESPD. In addition to that, the ZS added compounds show both a better processability and mechanical properties compared to the S2 ones at low concentration due to improved compatibility between zinc soap and CIIR matrix. Only the ZS added compound shows both improved processabilities (Mooney, Extrusion torque-& pressure) and improved mechanical properties (degree of crosslinking, elongation modulus, tear, and fatigue to failure counts) on both CIIR/hard clay/CB and CIIR/soft clay/CB compounds.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.48 no.6
• /
• pp.51-56
• /
• 2011

The surface of magnetic iron oxide nanoparticles (${\gamma}-Fe_2O_3$) is functionalized ($-NH_2$, -COOH) with bifunctional organic molecules and evaluated using FT-IR (Fourier transform infrared spectroscopy). We immobilize 21-base pair probe DNA and hybridize fluorescence-labeled (Cy5) target DNA onto the functionalized iron oxide nanoparticles. The fluorescence images obtained from a confocal microscopy show that the functionalized iron oxide nanoparticles should detect the hybridization of complementary and noncomplementary DNA.

• Biomedical Science Letters
• /
• v.12 no.4
• /
• pp.393-398
• /
• 2006

These studies were carried out to characterize the physiological functionalities of Codonopsis lanceolata, Cornus officinalis, and their mixtures. We investigated the antioxidative, fibrinolytic, and ${\alpha}$-glucosidase inhibitory activities of them. The antioxidative activities of Codonopsis lanceoiata and Cornus officinalis were 87% and 90%, respectively. Addition of salt to Codonopsis lanceolata and Cornus officinalis did not affect its antioxidative activities. In spite of fourfold addition of Codonopsis lanceolata to Cornus officinalis, the antioxidative activity was conserved at 90%. The fibrinolytic activities of Codonopsis lanceolata and Cornus officinalis were 0.78 plasmin unit/ml and 1.74 plasmin unit/ml, respectively. Addition of salt decreased the fibrinolytic activities of both Codonopsis lanceolata and Cornus officinalis. A mixture (3:1) of Codonopsis lanceolata and Cornus officinalis exhibited a 21% increase in activity. The ${\alpha}$-glucosidase inhibitory activities of Codonopsis ianceoiata and 100-fold diluted Cornus officinalis were 25% and 73%, respectively. The addition of salt to Codonopsis lanceolata and Cornus officinalis slightly decreased their ${\alpha}$-glucosidase inhibitory activities. According to the addition of Cornus officinalis to Codonopsis lanceoiata, the ${\alpha}$-glucosidase inhibitory activities of the resulting mixture were highly increased. We anticipate that these results will be used as basic data for the development of new bifunctional foods.

• BMB Reports
• /
• v.29 no.4
• /
• pp.365-371
• /
• 1996

Partially reduced interferon-a ($IFN-{\alpha}$) was cross-linked with thymosin ${\alpha}1$ ($T{\alpha}1$) using sulfo-succinimidyl (4-iodoacetyl) amino benzoate (SIAB), a bifunctional cross-linking reagent. The partially reduced $IFN-{\alpha}$ optimal for the cross-linking reaction was obtained by incubating native $IFN-{\alpha}$ with 0.5 mM DTT at $30^{\circ}C$ for 60~100 min. $T{\alpha}1$ was activated by incubating with sulfo-SIAB at $37^{\circ}C$ for 30 min to produce $T{\alpha}1-IAB$. The $T{\alpha}1-IFN-{\alpha}$ cross-linking was achieved by the reaction of the partially reduced $IFN-{\alpha}$ with $T{\alpha}1-IAB$. This cross-linking was between the sulfhydryl group of Cys1 in $IFN-{\alpha}$ and the N-terminal amino group of $T{\alpha}1$ through acetyl amino benzoate as a spacer. The immunological activity of the cross-linked molecule showed the same extent as that of $T{\alpha}1$, and most of the antiviral activity was retained compared to that of the partially reduced $IFN-{\alpha}$.

• Journal of Microbiology
• /
• v.43 no.3
• /
• pp.237-243
• /
• 2005

The protease purified from Bacillus cereus JH108 has the function of leucine specific endopeptidase. When measured by hydrolysis of synthetic substrate (N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide), the enzyme activity exhibited optimal activity at pH 9.0, $60^{\circ}C$. The endopeptidase activity was stimulated by $Ca^{++},\;Co^{++},\;Mn^{++},\;Mg^{++},\;and\;Ni^{++}$, and was inhibited by metal chelating agents such as EDTA, 1,10-phenanthroline, and EGTA. Addition of serine protease inhibitor, PMSF, resulted in the elimination of the activity. The endopeptidase activity was fully recovered from the inhibition of EDTA by the addition of 1 mM $Ca^{++}$, and was partially restored by $Co^{++}\;and\;Mn^{++}$, indicating that the enzyme was stabilized and activated by divalent cations and has a serine residue at the active site. Addition of $Ca^{++}$ increased the pH and heat stability of endopeptidase activity. These results show that endopeptidase requires calcium ions for activity and/or stability. A Lineweaver-Burk plot analysis indicated that the $K_m$ value of endopeptidase is 0.315 mM and $V_{max}$ is 0.222 ) is $0.222\;{\mu}mol$ of N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide per min. Bestatin was shown to act as a competitive inhibitor to the endopeptidase activity.