• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.435-441
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• 2010

We report the preparation and characterization of a new and water soluble complex of palladium(II) with 1,10- phenanthroline and butyldithiocarbamate ligands. This compound has been studied through spectroscopic techniques, $^1H$ NMR, IR, electronic spectra and elemental analysis and conductivity measurements. The complex shows 50% cytotoxic concentration ($Ic_{50}$) value against chronic myelogenous leukemia cell line, K562, much lower than that of cisplatin. Thus the mode of binding of this complex to calf thymus DNA have been extensively investigated by isothermal titration UV-visible spectrophotometry, fluorescence, gel filteration and other methods. UV-visible studies show that the complex exhibits cooperative binding with DNA and remarkably denatures the DNA at extremely low concentration ($~13\;{\mu}M$). Fluorescence studies indicate that the complex intercalate into DNA. Gel filtration studies suggest that the binding of Pd(II) complex with DNA is strong enough that it does not readily break. In these interaction studies, several thermodynamic and binding parameters are also determined which may reflect the mechanism of action of this type of compound with DNA.

• Bulletin of the Korean Chemical Society
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• v.21 no.12
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• pp.1217-1221
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• 2000

L-alanine dehydrogenase from Bacillus subtilis exhibits allosteric kinetic properties in the presence of $ZN^{2+}$. $ZN^{2+}$ induces the binding of substrate (L-alanine) to be cooperative at pH 8.0. The effect of pH variation between pH 7.0 and pH 10.0 on the inhibition by $ZN^{2+}$ correlates with the pH effect on the $K_m$ values for L-alanine within these pH range indicating that $ZN^{2+}$ and substrate compete for the same site. No such cooperativity is induced by $ZN^{2+}$ when the reaction is carried out at pH 10. At this higher pH, $ZN^{2+}$ binds with the enzyme with lower affinity and noncompetitive with respect to L-alanine. Inhibition of L-alanine dehydrogenase by $ZN^{2+}$ depends on the ionic strength. Increase in KCI concentration reduced the inhibition, but allosteric property in $ZN^{2+}$ binding is conserved. A model for the regulatory mechanism of L-alanine dehydrogenase as a noncooperative substrate-cooperative cofactor allosteric enzyme, which is compatible in both concerted and the sequential allosteric mechanism, is proposed.

• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.562-567
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• 1999

Single-stranded DNA binding protein (SSB) is well-characterized as having a helix-destabilizing activity. The helix-destabilizing capability of SSB has been re-examined in this study. The results of restriction endonuclease protection assays and titration experiments suggest that the stimulatory effect of SSB on strand exchange acts by melting out the secondary structure which is inaccessible to RecA protein binding; however, SSB is excluded from regions of secondary structure present in native single-stranded DNA. Complexes of SSB and RecA protein are required for eliminating the secondary structure barriers under optimal conditions for strand exchange.

• Bulletin of the Korean Chemical Society
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• v.4 no.2
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• pp.68-72
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• 1983

The $pK_{a}$ of $-NH_{3}^{+}$ group of chitosan in water was 6.2, while that of D-glucosamine-HCl, monomer of chitosan, was found to be 7.8. The difference of $pK_{a}$ values between chitosan and D-glucosamine was attributed to the strong electrostatic interaction between $-NH_{3}^{+}$ groups in chitosan. The apparent binding constant of $Cu^{2+}$ to D-glucosamine was estimated to be $1{\times}10^{4}$. For chitosan, no significant binding of $Cu^{2+}$ to the polymer was observed when pH < 5, but strong cooperative binding was observed near pH 5.1. The mechanism of such cooperativity was proposcd. Chitosan in solution exhibited typical polyelectrolytic behaviors: viscosity increases with increased amount of charged group, and decreases with addition of salt. The concentration dependence of viscosity was measured, and the Huggins parameters and intrinsic viscosity were calculated at various ionic strength. The results were interpreted in terms of molecular properties of the chitosan molecule.

• Bulletin of the Korean Chemical Society
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• v.14 no.6
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• pp.726-732
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• 1993

A comparative study on cadmium(II) complexation with three well characterized humic acids (SHA: soil humic acid from the Okchun Metamorphic Belt; AqHA: aquatic humic acid from Gorleben underground aquifer, Germany; CoHA: commercially available humic acid from the Aldrich Co.) was carried out in 0.1 M $NaClO_4$ at different solution pH(5.0, 5.5, and 6.0) using the ultrafiltration technique. The maximum binding ability (MBA) of the humic acids for cadmium(II) was observed to vary with their origins and solution pH. The results suggest that 1 : 1 complex predominates within the experimental range, and the conditional stability constants were calculated based on the assumption of cooperative binding, yielding log K values that were quite similar (CoHA: 4.17${\pm}$0.08; AqHA: 4.14${\pm}$0.07; SHA: $4.06{\pm} 0.12\;l\;mol^{-1}$ at pH 6.0) irrespective of humic acid origins or pH. By contrast a nonlinear Schatchard plot was obtained, using the cadmium(II) ion selective electrode speciation analysis method, which indicated that humic acid may have two or more classes of binding sites, with $log\;K_1\;and\;log\;K_2$ of 4.73${\pm}$ 0.08 and $3.31{\pm}0.14\;l\;mol^{-1}$ respectively.

• BMB Reports
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• v.40 no.5
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• pp.740-748
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• 2007

To gain insight into the structure and function of repressor proteins of bacteriophages of gram-positive bacteria, repressor of temperate Staphylococcus aureus phage ${\phi}11$ was undertaken as a model system here and purified as an N-terminal histidine-tagged variant (His-CI) by affinity chromatography. A ~19 kDa protein copurified with intact His-CI (~ 30 kDa) at low level was resulted most possibly due to partial cleavage at its Ala-Gly site. At ~10 nM and higher concentrations, His-CI forms significant amount of dimers in solution. There are two repressor binding sites in ${\phi}11$ cI-cro intergenic region and binding to two sites occurs possibly by a cooperative manner. Two sites dissected by HincII digestion were designated operators $O_L$ and $O_R$, respectively. Equilibrium binding studies indicate that His-CI binds to $O_R$ with a little more strongly than $O_L$ and binding species is probably dimeric in nature. Interestingly His-CI binding affinity reduces drastically at elevated temperatures ($32-42^{\circ}C$). Both $O_L$ and $O_R$ harbor a nearly identical inverted repeat and studies show that ${\phi}11$ repressor binds to each repeat efficiently. Additional analyses indicate that ${\phi}11$ repressor, like $\lambda$ repressor, harbors an N-terminal domain and a C-terminal domain which are separated by a hinge region. Secondary structure of ${\phi}11$ CI even nearly resembles to that of $\lambda$ phage repressor though they differ at sequence level. The putative N-terminal HTH (helix-turn-helix) motif of ${\phi}11$ repressor belongs to the HTH -XRE-family of proteins and shows significant identity to the HTH motifs of some proteins of evolutionary distant organisms but not to HTH motifs of most S. aureus phage repressors.

• Journal of the Korean Society of Clothing and Textiles
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• v.20 no.4
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• pp.655-666
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• 1996

The effect of protease (subtilisin Carlsberg) on the removal of hemoglobin as protein soil was studied. The relation between the renloval and the hydrolysis of hemoglobin by subtilisin Carlsberg was discussed. The soiled babric was prepared by spotting of hemoglobin solution evenly on the cotton fabric and was denatured by steaming. The soiled fabric was washed by using Terg-0-Tometer at various conditions. The removal efficiency was evaluated by analysis of protein on the fabrics before and after washing by means of copper-Folin method. 1. The removal of hemoglobin was increased in proportion to increasing of the enzyme concentration up to a certain point, but it began to decrease above the point. 2. The hemoglobin was removed effectively by adding of subtilisin Carlsberg, and more effectively removed by adding of AOS in the enzyme solution. 3. The removal of hemoglobin deviated from the first order reaction in detergency. 4. The renloval of hemoglobin was highest at $50^{\circ}C$ in detergency, Even at low temperature the removal efficiency of enzyme was relatively higher compared with the hydrolysis of hemoglobin by the enzyme. However the removal of hemoglobin was apparently decreased with the increase of temperature over $60^{\circ}C$. 5. The removal of hemoglobin was relatively high at pH 7.0~8.0 and increased continuously with the increase of pH in detergency 6. In detergency, the removal mechanism of hemoglobin by subtilisin Carlsberg could be explained as follows: Fisrt of all, the enzyme hydrolyzed hemoglobin substrates partially by forming E-S complex at the surface of hemoglobin on the cotton fiber, and decomposed cooperative binding of hemoglobin. Subsequently, the fragments of hemoglobin were easily removed by washing. According as the enzyme penetrated to inner part of hemoglobin gradually, the hemoglobin on the cotton fiber was effectively removed by the repetition of these process. The removal of hemoglobin was more effectively increased by adding both the enzyme and AOS in the washing solution. Therefore, it was regarded that AOS molecules were adsorbed at the hydrophobic surface of denatured hemoglobin, subsequently, decomposed more effectively cooperative binding of hemoglobin, and the fragments of hemoglobin were removed more efficiently by means of the interfacial reaction of AOS.

• Journal of Korea Trade
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• v.25 no.6
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• pp.1-19
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• 2021

Purpose - This paper aims at analyzing the functions and effectiveness of the cooperation agenda in Free Trade Agreements (FTAs), focusing on the cases of Asian countries. This paper estimates the contribution of this agenda to the sustainable development in Asia by providing the 'side payment' of the economic integration that encourages foreign investment and change in global value chains (GVC). Design/methodology - This study analyzes the functions of the cooperation chapter in FTAs by applying the cooperative game theory and reviewing the structures of the related FTAs. Also, as an empirical study, the existing FTA provisions and related development assistant programs in Asia are reviewed in this paper, especially focusing on the FTAs signed by Korea. Findings - Our main findings can be summarized as follows: The drawback of the economic integration, which would be the imbalanced economic benefit, can be redressed by the cooperation chapter in FTAs functioning as a 'side payment'. Indeed, as the examples of Korean FTAs show, more foreign investment and the GVC expansion in Asian countries have been encouraged thanks to the implementation of the cooperation chapters. Originality/value - This paper attempts to find how a legally binding agreement would influence the cooperation agenda in Asia which has never been analyzed despite the increasing number of so-called 'cooperation' chapters in the FTAs.

• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.1
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• pp.30-43
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• 2003

The geography, circulation pattern, and ecology show that the semi-closed seas of Northwest Pacific be managed as one complete system. Ongoing multilateral cooperative efforts relevant to marine environmental protection in the Northwest Pacific area, include the Working Group for the Western Pacific (WESTPAC) established under the auspices of WNESCO's Intergovernmental Oceanographic Commissions, the UNDP/GEF Programme on Prevention and Management of Marine Pollution in East Asian Seas (PEMSEA), the North Pacific Marine Science Organization(PICES), and the United Nations Environment Programme(WNEP)'s Northwest Pacific Action Plan(NOWPAP). The present report firstly describes the current situations on the existing regional cooperative regimes for marine environmental conservation in the Northwest Pacific region, with a special respect to the Northwest Pacific Action Plan(NOWPAP) which was adopted in 1994 by Japan, People's Republic of China, Republic of Korea and Russian Federation. Then, problems of the existing regimes are also discussed, together with the suggestion of the possible solutions, focusing on NOWPAP. Suggestions include: 1) the Northeast Asian countries should understand the importance of legally-binding regional convention, and should build up any legally-binding instrument which can function as a big umbrella for real regional cooperation without prejudice to the rights of the States, 2) At present stage, it will be possible to make a regional convention flexible without prejudice to the sovereign right of the States or territorial issues; 3) taking into account that the region often faces many generic political problems that often inhibit the effective collective actions on environmental issues, the leadership from UNEP or other international organizations is required; 4) strong institutional and financial framework should be made, and 5) multilateral efforts to respond to the new marine environmental threats should be taken at the regional level in order to protect the coastal and marine environments in the Northwest Pacific.

• Bulletin of the Korean Chemical Society
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• v.30 no.9
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• pp.1951-1955
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• 2009

A Thermodynamic study on the interaction of bovine calf thymus DNA with new designed Pd(II) complex (Ethylendiamine- 8-hydroxyquinolinato Palladium(II) chloride) was studied by using isothermal titration calorimetry (ITC) at 27 ${^{\circ}C}$ in Tris buffer solution at pH = 7.5. The enthalpies of Pd(II) complex + DNA interaction are reported and analysed in terms of the new solvation theory. It was indicated that there are three identical and non-cooperative sites for Pd(II) complex. The binding of a Pd(II) complex is endothermic with association equilibrium constants of 428.03 m$M^{-1}$ at 27 ${^{\circ}C}$. The binding of Pd(II) complex can cause some changes in the stability of the DNA at low and high Pd(II) complex concentrations. Our results suggested that this complex might interact with DNA as an intercalator, thus interfering with DNA replication and cell proliferation.