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

• Bulletin of the Korean Chemical Society
• /
• v.30 no.9
• /
• pp.1956-1962
• /
• 2009

The binding abilities of two multidentate tripodal amine catechol ligands, cis,cis-1,3,5-tris[(2,3-dihydroxybenzylamino) aminomethyl]cyclohexane (TMACHCAT, $L^1)\;and\;N^1,N^3,N^5$-tris(2-(2,3-dihydroxybenzylamino) ethyl)cyclohexane-1,3,5-tricarboxamide (CYCOENCAT, $L^2$) with Ga(III) and In(III) have been investigated by potentiometric and spectrophotometric methods in an aqueous medium of 0.1 M KCl at 25 ${\pm}\;1\;{^{\circ}C}.$ The ligands $L^1\;and\;L^2$ formed various monomeric species $MLH_3,\;MLH_2$, MLH and ML (M = $Ga^{+3}\;and\;In^{+3}$) and showed potential to form strong encapsulated tris(catechol) type complexes. The coordination modes, binding ability and selectivity of the ligands towards Ga(III) and In(III) have been discussed with the help of experimental evidences, and supported with molecular modeling calculations.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.8
• /
• pp.1188-1192
• /
• 2003

In order to study the role of residue in the active site of glutathione S-transferase (GST), Tyr 108 residue in human GST P1-1 was replaced with alanine, phenylalanine and tryptophan by site-directed mutagenesis to obtain mutants Y108A, Y108F and Y108W. These three mutant enzymes were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. The substitutions of Tyr108 significantly affected $K_m^{CDNB}$ and $K_m^{ETA}$, whereas scarcely affected $K_m^{GSH}$. The substitutions of Tyr108 also significantly affected $I_{50}$ of ETA, an electrophilic substrate-like compound. The effect of these substitutions on kinetic parameters and the response to inhibition suggests that tyrosine 108 in hGST P1-1 contributes to the binding of the electrophilic substrate and a major determinant in the binding of CDNB is the aromatic ring of Tyr108, not its hydroxyl group.

• Analytical Science and Technology
• /
• v.9 no.1
• /
• pp.91-97
• /
• 1996

The extent of binding($K_B$) between chemical compound and humic acid was measured as an indicator of decrease in toxicity. From the experimental $K_B$ and estimated $K_B$ calculated from $K_{ow}$, no reduction of toxicity among test chemicals in aquatic systems were predicted except P,P'-DDT. The effect of humic acid on aquatic organisms is not expected to be significant for the compounds with $K_B{\leq}10^5$ or $K_{ow}{\leq}10^6$.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.594-598
• /
• 2005

Treatment of a solution of $CuCl_2$ in dimethyl phosphate (DMP) with DMSO under nitrogen atmosphere afforded to a light blue fluorescence powder. Slow evaporation of $H_2O$-DMSO solution of this powder resulted in blue-sky crystals of a new polymeric Cu(II) complex, with a unit cell composed of $Cu_2(DMP)_4$(DMSO), (1). The crystal and molecular structure of the complex acquired crystallographically. Compound (1) crystallizes in the monoclinic space group $P2_1$/n with a = 12.8920(11) $\AA$, b = 13.1966(11) $\AA$, c = 14.7926(13) $\AA$, $\alpha$ = 90$^{\circ}$, $\beta$ = 98.943(2)$^{\circ}$, $\gamma$ = 90$^{\circ}$, V= 2486.1(4) ${\AA}^3$, and Z = 4. A square pyramidal environment for the metal center was established by coordination of oxygen atoms of four bridging DMP ligands in the basal positions and binding a tri-centered oxygen atom of DMSO in the apical disposition of Cu(II). The sixth position was also affected by a weak interaction with the sulfur atom of another DMSO. The phosphorous atom in the bridging DMP was arranged in a deformed tetrahedron with (gg) conformation for methyl esters with $C_{2v}$ symmetry.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.4
• /
• pp.548-552
• /
• 2005

The interaction between ionic surfactants and different nonionic molecules and polymers are studied using ion surfactant selective electrode. From the experimental data, critical concentrations of the interaction and binding process are evaluated. The interaction between hexadecyltrimethylammonium bromide (HTAB) with polyethylene glycol (PEG) in three molecular weights (1000, 10000 and 100000) and also schiff-bases, 2-[2-carboxyphenyl nitrilomethylidyne]-phenol (ortho CNP), 2-[3-carboxyphenyl nitrilomethylidyne]-phenol (meta CNP)and 2-[4-carboxyphenyl nitrilomethylidyne]-phenol (para CNP) with the potentiometric method were investigated using HTAB membrane selective electrode. In the case of PEG with increasing molecular weights more interaction to HTAB occurs. The electromotive force (EMF) data also showed that interaction between para CNP with HTAB is more than the other schiff-bases. It seems this case related to less space interference of COOH group for that compound. The onset of binding ($T_1$) of course is the same for three schiffbase molecules.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.1
• /
• pp.61-68
• /
• 2008

High initial (2 minutes after iv injection) brain-uptake of PET agents is required to deliver the agent to binding sites in brain tissue but, for quantification of the specific binding, relatively rapid washout of free and non-specifically bound PET agents from the brain (30 minutes after injection) also is required. In order to compare the physicochemical properties of the PET agents which are responsible for early brain-uptake and rapid washout, respectively, chemometric analysis on brain-uptake of PET agents was performed via a classical VolSurf approach. According to the PCA and PLS results, high 2-30 min brain-uptake ratio seems to be related to the large hydrophobic regions in the PET agents which are not confined to a particular surface.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.7
• /
• pp.1141-1150
• /
• 2007

Molecular modeling study has been performed to assist in the design of PTP1B inhibitors using FlexX. FlexX dockings with 19 test ligands, whose structures have been determined by X-ray crystallography, were successful in reproducing the experimental conformations within the protein. An increase in biological activity is observed as hydrophobic character of formylchromone derivatives increases. Most ligands bind to the activesite regions of the protein successfully in two different score runs. The Drug score run gave better results than the FlexX score run based on the score, rank, binding modes and bond distance of docked structures. Consensus values from the CScore scoring function are between 3 and 5, suggesting that the scoring scheme is reliable. All formylchromone inhibitors considered in this work show unidirectional binding modes in the active site pocket, which is contrary to the bidirectional X-ray results by Malamas et al. and amino acid residues responsible for such orientation are identified to help further development of the inhibitors.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3261-3266
• /
• 2011

The interaction of bilobalide (BB) and ginkgolides B (GB) with bovine serum albumin (BSA) was investigated by fluorescent technique and UV/vis absorption spectroscopy. The results showed that BB and GB could intensively quench the fluorescence of BSA through a static quenching procedure. The binding constants (Ka) and the average binding distance between the donor (BSA) and the acceptor (ginkgolides) were obtained ($r_{BB}$ = 5.33 nm and $r_{GB}$ = 4.20 nm) by the theory of non-radiation energy transfer, and then the thermodynamic parameters such as ${\Delta}S^0$ (0.17-0.32 kJ/mol), ${\Delta}G^0$ (-20.76 ~ -17.79 kJ/mol) and ${\Delta}H^0$ (32.47-76.52 kJ/mol) could be calculated, respectively. All these results revealed that the interaction of BB and GB with BSA were driven mainly by hydrophobie force. The synchronous fluorescence spectroscopy was applied to examine the effect of two ginkgolides on the configuration of BSA. The configuration alteration of BSA could be induced by the hydrophobicitv environment of tyrosine with the increase of the drug concentration.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.9
• /
• pp.3219-3222
• /
• 2011

Three types of ${\beta}$-ketoacyl acyl carrier protein synthase (KAS) are important for overcoming the bacterial resistance problem. Recently, we reported the discovery of a antimicrobial flavonoid, YKAF01 (3,6-dihydroxyflavone), which exhibits antibacterial activity against Gram-positive bacteria through inhibition of ${\beta}$-ketoacyl acyl carrier protein synthase III (KAS III). In this report, we suggested that YKAF01 can be an inhibitor ${\beta}$-ketoacyl acyl carrier protein synthase I (KAS I) with dual inhibitory activity for KAS I as well as KAS III. KAS I is related to the elongation of unsaturated fatty acids in bacterial fatty acid synthesis and can be a good therapeutic target of designing novel antibiotics. We performed docking study of Escherichia coli KAS I (ecKAS I) and YKAF01, and determined their binding model. YKAF01 binds to KAS I with high binding affinity ($2.12{\times}10^6$) and exhibited an antimicrobial activity against the multidrug-resistant E. coli with minimal inhibitory concentration (MIC) value of 512 ${\mu}g$/mL. Further optimization of this compound will be carried out to improve its antimicrobial activity and membrane permeability against bacterial cell membrane.