• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.367-373
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• 2013

The ruthenium(II) ferrocenyl heterocyclic thiosemicarbazone complexes of the type $[RuCl(CO)(EPh_3)]_2L$ (where E = P/As; L = binucleating monobasic tridendate thiosemicarbazone ligand) have been investigated. Strutural features were determined by analytical and spectral techniques. Binding of these complexes with CT-DNA by absorption spectral study indicates that the ruthenium(II) complexes form adducts with DNA and has intrinsic binding constant in the range of $3.3{\times}10^4-1.2{\times}10^5M^{-1}$. The complexes exhibit a remarkable DNA cleavage activity with CT-DNA in the presence of hydrogen oxide and the cleavage activity depends on dosage.

• Korean Journal of Microbiology
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• v.29 no.5
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• pp.307-313
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• 1991

A yellow-green, fluorescent siderophore A3 was extracellularly produced under iron-limited growth conditions from Pseudomonas synxantha A3. The physicochemical and biological properties of siderophore A3 were examined. The approxiamte molecular weights of the Fe(III)-siderophore A3-1 complex and Fe(III)-siderophore A3-2 complex were estimated to be about 1,300 and 1,100, respectively, by Bio-gel P2 gel exclusion chromatography. The molar ratio between the siderophore and the Fe(III)was 1.08 mole. The molecular weight of the complex could be calculated with this ratio and the new values were 1,150 and 960, respectively. The binding constant(K) between thesiderophore A3 and Fe(III) that determined by displacing the iron from the Fe(III)-siderophore complex with EDTA was 4.12*10$^{18}$ at pH 5.0. Siderophore A3 appeared to have antibacterial activity on several bacterial strains, however, ferric siderophore Ae complex did not show that activity. The cytotoxicity of siderophore A3 was obtained from Human Chronic Myelogenous Leudemia K562 cells. Inhibition concentration (50%)($IC_{50}$ ) was $0.17\mu$\{g/ml}.

• BMB Reports
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• v.29 no.4
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• pp.353-358
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• 1996

Bovine angiogenin (bAng) is a potent blood vessel inducing protein purified from cow In ilk. fluorescence spectroscopy has been used to study the interaction of bAng with actin in 50 mM Tris-HCl pH 7.5, and 1 mM $CaCl_2$ at $25^{\circ}C$. Actin contains four tryptophans but bAng contains no tryptophans. A 50% decrease in intrinsic fluorescence accompanied formation of the bAng/actin complex. By contrast, the interaction of RNase A, a homologous protein to bAng, with actin results in about 10% quenching of the fluorescence. Fluorescence titration experiments were performed by adding increasing concentrations of bAng (0~1.0 ${\mu}M$) to a constant concentration of actin (0.1 ${\mu}M$), and the dissociation constant $K_d$ for the bAng/actin complex and the stoichiometry n were measured as $20{\pm}1$ nM and $1.0{\pm}0.1$ respectively. These results suggest that the interaction between bAng with actin is specific and that quenching of actin fluorescence has occurred in the bAng/actin complex. The bAng binding sites of actin are discussed in the results of this study, and we propose that Trp-80 in the small domain of bovine actin is responsible for the bAng/actin binding.

• The Korean Journal of Pharmacology
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• v.20 no.2
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• pp.23-34
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• 1984

To investigate diurnal variations of opiate receptor binding and its modification by experimental condition or treatment of various centrally-acting drugs, the amount of maximum $^3H-morphine$ binding in rat midbrain homogenates was measured at 4 hour intervals for 24 hours. Animals were conditioned under the controlled L : D, 12 : 12 cycle or D: D, 12 : 12 cycle, for 3 weeks and treated with 0.5 ml of physiological saline or drugs for 2 weeks. A highly significant diurnal rhythm with peak at 22 hour of early dark phase with an amplitude$(0.68{\pm}0.06\;pmole/mg\;protein)$ of +51.1% and nadir $(0.33{\pm}0.03\;mole/mg\;prtein)$ at 18 hour of late light phase with an amplitude of -26.6% was found in control group. 24 tour mean of $^3H-morphine$ binding was $0.45{\pm}0.03\;pmole/mg$ protein respectively. Constant dark adaptation or treatment of reserpine, pargyline, imipramine, amphetamine and chlorpromazine modified the diurnal rhythm in the time of peak and nadir binding shape, phase, amplitude of the diurnal curve and 24 hour mean of $^3H-morphine$ binding. However, Kd values were not changed in all experimental groups : Statistical analysis at times of least and great binding indicates that the differences in $^3H-morphine$ binding were due to changes not in the affinity, but in the number of binding sites. The results are interpreted with regard to the diurnal rhythm of opiate receptor finding. The modes of action of psychoactive drugs are closely related to postulated changes of receptor sensitivity in neuropharmacological aspects.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.6
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• pp.344-351
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• 2002

Chemical speciation and transport of heavy metals in soil environment could be controlled by humic acid. In order to understand the mechanism on competitive adsorption of Cd and Cu on the surface of humic acid extracted from peat, the charge development of humic acid were investigate through a batch adsorption experiment with a series of different background electrolytes levels. The competitive adsorption of Cd and Cu to the humic acid were estimated according to the model using the proton binding constant obtained from the above batch test. The affinity of Cu to the carboxyl group on the humic acid was higher than that of Cd, but the affinity to the phenolic group was lower than to the carboxyl group. It seems that the amount of adsorbed Cd and Cu could be estimated using the proton binding constant obtained from a solution with single background ion. However, it is difficult to interpret the competitive adsorption of Cd and Cu with the constant for single background ion.

• BMB Reports
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• v.38 no.4
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• pp.407-413
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• 2005

Calcium and zinc binding protein, calprotectin is a multifunctional protein with broad spectrum antimicrobial and antitumoural activity. It was purified from human neutrophil, using a two-step ion exchange chromatography. Since surface hydrophobicity of calprotectin may be important in membrane anchoring, membrane penetration, subunits oligomerization and some biological roles of protein, in this study attempted to explore the effect of calcium in physiological range on the calprotectin lipophilicity. Incubation of human calprotectin ($50\;{\mu}g/ml$) with different calcium concentrations showed that 1-anilino-8-naphthalene sulfonic acid (ANS) fluorescence intensity of the protein significantly elevates with calcium in a dose dependent manner, suggesting an increase in calprotectin surface hydrophobicity upon calcium binding. Our study also indicates that calcium at higher concentrations (6, 8 and 10 mM) induces aggregation of human calprotectin. Our finding demonstrates that the starting time and the rate constant of calprotectin aggregation depend on the calcium concentration.

• YAKHAK HOEJI
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• v.40 no.6
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• pp.734-738
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• 1996

The development of the alpha2 isoform of (Na,K)ATPase which is high affinity ouabain receptors was studied in the differentiating nonfusing muscle cell line BC3H-1. T he differentiation process of BC3H-1 cell line was confirmed by 2-dexy-D-[$^3$H] glucose uptake experiment and the quantity of the expression of ${\alpha}_2$ isoform was measured using a whole cell [$^3$H] ouabain-binding assay. Undifferentiated growing BC3H-1 cells, myoblasts, exhibited low levels of insulin-stimulated glucose uptake and [$^3$H] ouabain-binding sites. In contrast, differentiated BC3H-1 cells, myocytes, had a 5.6-fold increase in insulin-stimulated glucose uptake and 5-fold increase in [$^3$H] ouabain-binding sites. Scatchard analysis showed that myocytes developed more [$^3$H] ouabain-binding sites than myoblasts vath a dissociation constant (kd) of 6${\times}10^{-8}$M and capacity of 6.l${\times}10^{-5}$ sites/cell. Therefore. it seems that myoblasts express low levels of ${\alpha}_2$ subunit and probably the majority of ${\alpha}_1$ subunit, whereas myocytes express high levels of ${\alpha}_2$ isoform. The results indicate that the expression of ${\alpha}_2$ isoform is developmentally regulated during differentiation and that BC3H-1 culture system provides an excellent model for the study of differentiation and mechanism of (Na,K)ATPase action in muscle which requires electrical excitability.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1445-1449
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• 2006

Molecular tweezers based on chenodeoxycholic acid bearing different lengths of arm were synthesized andtheir anion binding affinities were evaluated by $^1H$ NMR, isothermal calorimetric titration, and ESI mass spectrometry. Molecular tweezer 6 showed a high selectivity toward $H_2PO_4\;^-$ over $Cl^-,\;Br^-,\;I^-, $ and $CH_3CO_2\;^-$ by $^1H$ NMR titration, whereas the association constant for $F^-$ revealed the largest value as determined by ITC. The selectivity of 6 towards $F^-$ was about 103 times higher than that of $Cl^-,\;H_2PO_4\;^- $, and $CH_3CO_2\;^-$. ITCexperiment of 6 with $F^-$ in a DMSO showed two binding modes; two sequential association constants $K_1\;=\;2.77\;{\times}\;10^5\;M^{-1}$ and $K_2\;=\;8.68\;{\times}\;10^6\;M^{-1}$ were found. These sequential bindings were confirmed by ESI massspectrometry. 1 : 1 and 1 : 2 complexes of 6 and $F^-$ were found at m/z 868.08 and 884.04.

• Journal of Microbiology and Biotechnology
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• v.25 no.4
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• pp.503-510
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• 2015

The iLOV protein belongs to a family of blue-light photoreceptor proteins containing a light-oxygen-voltage sensing domain with a noncovalently bound flavin mononucleotide (FMN) as its chromophore. Owing to advantages such as its small size, oxygen-independent nature, and pH stability, iLOV is an ideal candidate over other reporter fluorescent proteins such as GFP and DsRed. Here, for the first time, we describe the feasibility of applying LOV domain-based fluorescent iLOV as a metal sensor by measuring the fluorescence quenching of a protein with respect to the concentration of metal ions. In the present study, we demonstrated the inherent copper sensing property of the iLOV protein and identified the possible amino acids responsible for metal binding. The fluorescence quenching upon exposure to Cu²⁺ was highly sensitive and exhibited reversibility upon the addition of the metal chelator EDTA. The copper binding constant was found to be 4.72 ± 0.84 µM. In addition, Cu²⁺-bound iLOV showed high fluorescence quenching at near physiological pH. Further computational analysis yielded a better insight into understanding the possible amino acids responsible for Cu²⁺ binding with the iLOV protein.

• BMB Reports
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• v.30 no.1
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• pp.1-6
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• 1997

The ability of Hep-G2 cells to process $[^{125}I]LDL$ under basal conditions was investigated. The receptor-binding and internalization of $[^{125}I]LDL$ increased with the time of incubation in a saturable manner. After 4 h of incubation, 31.4 ng of $[^{125}I]LDL$ was cell bound. The cells rapidly internalized $[^{125}I]LDL$ via specific, receptor-mediated endocytosis. The amount of internalized $[^{125}I]LDL$ reached a maximun of 96.7 ng at 2 h of incubation and remained constant for the next 2 h. The rate of degradation of internalized $[^{125}I]LDL$ proceeded in a linear manner over the entire 4 h of incubation after an initial lag period. The effects of individial fatty acids (C18:0. C18:1, C18:2. and C18:3), differing in their degree of unsaturation. on the receptor-binding, internalization and degradation of $[^{125}I]LDL$ were also investigated. Inclusion of 1.0 mM of each fatty acid into the culture medium significantly increased $[^{125}I]LDL$ metabolism in Hep-G2 cells. Among the fatty acids tested, stearic acid had the least effect on the receptor-binding activity. There were no significant differences among the unsaturated fatty acids in LDL-receptor binding. The effect of individual fatty acids on the $[^{125}I]LDL$ uptake was similar to that of the receptor-binding. showing a significantly lower effect with stearic acid. The amount of degraded material of internalized $[^{125}I]LDL$ was the lowest with stearic acid when it was compared with unsaturated fatty acids.