• Journal of Life Science
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• v.8 no.2
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• pp.119-125
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• 1998

Column-purified double-stranded RNA binding factor (RBF) protein was tested for its binding affinity for the different forms of nucleic acids structure such as single-stranded(ss) and double-stranded(ds)RNA and ss- and dsDNA. The RBF protein was incubated with each of these nucleic acid structures in separate reactions and its comparative binding affnity was visualized by SDS-polyacrylamide gel electrophoresis. The RBF protein bound to the dsRNA molecule to form a tight RNA:protein complex in agreement with previous studies, but not to the other nucleic acid molecules confirming its distinctive affinity for the dsRNA structure. In phosphorylation assay in vito, the purified RBF protein significantly inhibited the autophosphorylation of the PKR derived from not only human but mouse source in the presence of poly(I):poly(C). It is suggesting that PKR vs. RBF is similarly under a competitive interaction among different eukaryotic organisms during protein synthesis.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1256-1260
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• 2003

Two O-methyltransferases, OMTII-1 and OMTII-4 of meadow rue Thalictrum tuberosum showed a high sequence identity. Of 364 amino acids only one residue is not the same, which is Tyr21 or Cys21. Even if the 21st residues in these OMTs are not included in the binding sites of the enzymes, binding affinities of the enzyme homodimers over the same substrate are very different. While the binding affinity of one homodimer over caffeic acid is 100%, that of the other is 25%. Authors tried to predict the three-dimensional structures of Thalictrum tuberosum O-methyltransferases using homology-based modelling by a comparison with caffeic acid O-methyltransferase, and explain the reason of the phenomenon mentioned above based on their three dimensional structural studies. In the enzyme homodimer, the better binding affinity may be caused by the shorter distance between the 21st residue and the binding site of the other monomer.

• The Korean Journal of Nuclear Medicine
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• v.17 no.2
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• pp.35-40
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• 1983

To evaluated the usefulness of cultured human fibroblast for insulin receptor assay, the authors cultured fibroblast from biopsied normal adult female eyelid skin and assayed the insulin receptor with radioreceptor assay method. From the data obtained, percent of labeled insulin bound, numbers of insulin binding sites, affinity constants(Ka) and affinity of the empty sites(Ke) were calculated. The results were as follow; 1) The percent radioactivity bound of cultured fibroblast reached plateau at 4 hours $15^{\circ}C$ incubation. 2) The scatchard plot of insulin binding to cultured human fibroblast was curvilinear and the affinity to receptor was decreased with increased receptor occupancy. 3) The numbers of high affinity, low affinity and total insulin receptor of cultured fibroblasts were 852, 24,800 and 25,652 sites per cell. 4) High and low affinity constants of cultured fibroblasts were $3.4\times^{10}M^{-1},\;and\;1.08\times10^8M^{-1}$, and the affinity of empty site was $5.0\times10^8M^{-1}$.

• KSBB Journal
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• v.16 no.2
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• pp.170-173
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• 2001

Liposome-amino acid conjugates were prepared using dipalmitolyphosphatidylcholine(DPPC) and hydrophobically modified asparagine. A microdialyzer was used to measure glucose diffusion. The glucose binding affinity of DPPC-ODA-asparagine liposomes higher than that of DPPC liposomes and distilled water. The size of DPPC-ODA-asparagine was approximately 75-150 nm. Cholesterol increased the stability of liposomes, and reduced the size of liposome particles.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.290-290
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• 1994

The binding characteristic of oxomemazine to muscarinic receptor in the cerebrum, heart, and ileum were compared to those of pirenzepine to investigate whether oxomemazine could classify the muscarinic receptor subtypes. 〔$^3$H〕Quinucl idinyl benzilate(QNB) identified a single class of muscarinic receptors with apparent K$\sub$D/ value of about 60 pM in three tissues. Analysis of the pirenzepine inhibition curve of 〔$^3$H〕QNB binding to cerebral microsome indicated the presence of two receptor subtypes with high (Ki=16 nM, M$_1$-receptor) and low (Ki=400 nM, M$_2$-receptor) affinity for pirenzepine. Oxomemazine also identified two receptor subtypes with high (Ki=84 nM, On-receptor) and low (Ki=1 4 ${\mu}$M, O$\sub$L/-receptor) affinity in rat cerebral microsome, The percentage population of the M$_1$-and M$_2$-receptors to the total receptors were 61 : 39, and those of the O$\^$H/- and O$\sub$L/-receptors 39 : 61, respectively, However, the Hill coefficients of these two drugs for the inhibition of 〔$^3$H〕QNB binding to the heart and ileum were close to unity which indicated that these drugs bound to a uniform population of receptors in these two tissues. The Ki values for the low affinity sites of pirenzepine and oxomemazine in the cerebrum were similar to those of these drugs in the heart ileum. Both pirenzepine and oxomemazine increased K$\sub$D/ value for 〔$^3$H〕QNB without affecting the binding sites concentration and Hill coefficient for the 〔$^3$H〕QNB binding. Oxomemazine had a 10-fold lower affinity at Ma-receptors than at M$_1$-receptors, and pirenzepine a 8-fold lower affinity at O$\sub$L/-receptors than OH-receptors. Analysis of the shal low competition curves of oxomemazine for the H$_1$ receptors and pirenzepine for the O$\sub$L/-receptors yielded that 69% of the M$_1$-receptors were of the O$\sub$H/-receptors and the remaining 31% of the O$\sub$L/-receptors, and that 29% of the O$\sub$L/-receptors were of the M$_1$-receptors and 71% of the M$_2$-receptors. However, M$_2$ for oxomemazine and O$\sub$H/ for pirenzepine were composed of a uniform population. These results suggest that oxomemazine could discriminatethe muscarnic receptor subtypes and may subclassify the M$_1$-receptors into two subtypes.

• Korean Journal of Microbiology
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• v.32 no.2
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• pp.102-108
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• 1994

Autonomously replicating sequence Binding Factor 1(ABF1) is a DNA-binding protein that specifically recognizes the $RTCRYN_5ACG$ at many sites in the yeast genome including the promoter element, mating-type silencer and ARS. To express the intact full-length ABF1 gene in E. coli, the ABF1 gene has been cloned into pMAL-c2 and His-61, Leu-353 and Leu-360 were substituted with other amino acid. ABF1 fusion proteins of wild type ABF1 and H61A, L353R and L360R nutants were purified by amylose resin affinity chromatography. Fusion protein of MBP and ABF1 was digested by Factor Xa and Characterized by gel retardation assay and complementation test. As aresult, we suggested that other DNA binding motif except atypical inc-finger motif is in the middle region of ABF1.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.464-466
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• 2010

• Korean Journal of Animal Reproduction
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• v.18 no.2
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• pp.95-99
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• 1994

The purpose of the present study was to determine the in vivo effect of oxytocin antagonist-I(Al) on uterine oxytocin receptor number (Rn) and/or binding affinity (Kd) in the estrous rat. Anesthetized rats were given a bolus infusion of control or 5${\mu}\textrm{g}$ of AI and sacri-ficed 0.5 and 4 hours later. The uterine tissue was removed, trimmed and frozen. Membrane oxytocin receptors were isolated after homogenization of uterine tissue and differential ultracentrifugation. The oxytocin receptor assay was performed by saturation with cold oxytocin competion with a high specific activity oxytocin antagonist. Rn and Kds were determined by nonlinear curve fitting methods. No differences(p>0.05) between the AI and control treated animals in either oxytocin receptor number or binding affinity was detected in this study. These data suggest that the major mode of action of AI is via competitive inhibition at the uterine oxytocin receptor and not by altering receptor number or binding affinity.

• Molecules and Cells
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• v.39 no.3
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• pp.217-228
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• 2016

To generate a biobetter that has improved therapeutic activity, we constructed scFv libraries via random mutagenesis of several residues of CDR-H3 and -L3 of hu4D5. The scFv clones were isolated from the phage display libraries by stringent panning, and their antiproliferative activity against HER2-positive cancer cells was evaluated as a primary selection criterion. Consequently, we selected AH06 as a biobetter antibody that had a 7.2-fold increase in anti-proliferative activity ($IC_{50}$: 0.81 nM) against the gastric cancer cell line NCI-N87 and a 7.4-fold increase in binding affinity ($K_D$: 60 pM) to HER2 compared to hu4D5. The binding energy calculation and molecular modeling suggest that the substitution of residues of CDR-H3 to W98, F100c, A101 and L102 could stabilize binding of the antibody to HER2 and there could be direct hydrophobic interactions between the aromatic ring of W98 and the aliphatic group of I613 within HER2 domain IV as well as the heavy and light chain hydrophobic interactions by residues F100c, A101 and L102 of CDR-H3. Therefore, we speculate that two such interactions were exerted by the residues W98 and F100c. A101 and L102 may have a synergistic effect on the increase in the binding affinity to HER2. AH06 specifically binds to domain IV of HER2, and it decreased the phosphorylation level of HER2 and AKT. Above all, it highly increased the overall level of p27 compared to hu4D5 in the gastric cancer cell line NCIN82, suggesting that AH06 could potentially be a more efficient therapeutic agent than hu4D5.

• Bulletin of the Korean Chemical Society
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• v.25 no.6
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• pp.791-795
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• 2004

The binding of cethyl trimethylammonium bromide, (CTAB) with human serum albumin (HSA) has been investigated at 5 mM phosphate buffer pH 7.0, 27 $^{\circ}C$ and various ionic strength using ion selective membrane electrodes. This method is faster and much more accurate than equilibrium dialysis technique, so provides sufficient and accurate data for binding data analysis. A novel and simple method was introduced for resolution and characterization of binding sets on basis of binding capacity concept. The values of Hill binding parameters were estimated for each set and used for calculation of intrinsic binding affinity. The results interpreted on basis of nature of forces which interfered in the interaction and represent the existence of three and two binding sets for binding of CTAB at $10^{-4}$ and $10^{-3}$ M of NaBr, respectively.