• BMB Reports
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• v.37 no.5
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• pp.538-545
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• 2004

A new CRT binding factor (CBF) gene designated Cbcbf25 was cloned from Capsella bursa-pastoris, a wild grass, by the rapid amplification of cDNA ends (RACE). The full-length cDNA of Cbcbf25 was 898 bp with a 669 bp open reading frame (ORF) encoding a putative DRE/CRT (LTRE)-binding protein of 223 amino acids. The predicted CbCBF25 protein contained a potential nuclear localization signal (NLS) in its N-terminal region followed by an AP2 DNA-binding motif and a possible acidic activation domain in the C-terminal region. Bioinformatic analysis revealed that Cbcbf25 has a high level of similarity with other CBF genes like cbf1, cbf2, and cbf3 from Arabidopsis thaliana, and Bncbf5, Bncbf7, Bncbf16, and Bncbf17 from Brassica napus. A cold acclimation assay showed that Cbcbf25 was expressed immediately after cold triggering, but this expression was transient, suggesting that it concerns cold acclimation. Our study implies that Cbcbf25 is an analogue of other CBF genes and may participate in cold-response, by for example, controlling the expression of cold-regulated genes or increasing the freezing tolerance of plants.

• BMB Reports
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• v.39 no.4
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• pp.406-411
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• 2006

Signaling lymphocyte activation molecule (SLAM; also known as CD150) is a newly identified cellular receptor for measles virus (MV). The interaction between MV Haemagglutin (MVH) and SLAM is an initial step for MV entry. We have identified several novel SLAM binding sites at residues S429, T436 and H437 of MVH protein and MVH mutants in these residues dramatically decrease the ability to interaction with the cell surface SLAM and fail to co-precipitation with SLAM in vivo as well as malfunction in syncytium formation. At the same time, K58, S59 and H61 of SLAM was also identified to be critical for MVH and SLAM binding. Further, these residues may be useful targets for the development of measles therapy.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.5
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• pp.523-523
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• 2003

The change of interactions of anionic surfactants, sodium dodecyl sulfate(SDS) and sodium tetradecyl sulfate(575) in the presence of electrolytes, to the chitosan-based polyelectrolyte(sol＇n and gel phase) were studied. The chitosan gel used in this study were crosslinked with epichlorohydrin(ECH). Binding isotherms were determined by potentiometric technique using a surfactant ion selective solid-state electrode and the results were represented by using the sequence generating function(SGF) method. The results of binding isotherm were shown comparatively high cooperativity. The addition of electrolytes in the chitosan/SDS system resulted in a shift of the binding to higher free surfactant concentration because of screen effect by the electrolytes. Degree of binding of chitosan gel was higher than that of chitosan sol＇n. And also a conformational phase transition of the chitosan gel in the presence of electrolytes has been investigated.

• Journal of the Korean Society of Clothing and Textiles
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• v.27 no.5
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• pp.524-532
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• 2003

The change of interactions of anionic surfactants, sodium dodecyl sulfate(SDS) and sodium tetradecyl sulfate(575) in the presence of electrolytes, to the chitosan-based polyelectrolyte(sol＇n and gel phase) were studied. The chitosan gel used in this study were crosslinked with epichlorohydrin(ECH). Binding isotherms were determined by potentiometric technique using a surfactant ion selective solid-state electrode and the results were represented by using the sequence generating function(SGF) method. The results of binding isotherm were shown comparatively high cooperativity. The addition of electrolytes in the chitosan/SDS system resulted in a shift of the binding to higher free surfactant concentration because of screen effect by the electrolytes. Degree of binding of chitosan gel was higher than that of chitosan sol＇n. And also a conformational phase transition of the chitosan gel in the presence of electrolytes has been investigated.

• Journal of Microbiology
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• v.44 no.3
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• pp.293-300
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• 2006

The Escherichia coli heat-labile enterotoxin B subunit (HLT-B) is one of the most powerful mucosal immunogens and known mucosal adjuvants. However, the induction of high levels of HLT-B expression in E. coli has proven a difficult proposition. Therefore, in this study, the HLT-B gene was cloned from pathogenic E. coli and expressed as a fusion protein with GST (glutathion S-transferase) in E. coli BL2l (DE3), in an attempt to harvest a large quantity of soluble HLT-B. The culture conditions, including the culture media used, temperature, pH and the presence of lactose as an inducer, were all optimized in order to obtain an increase in the expression of soluble GST-rHLT-B. The biological activity of the purified rHLT-B was assayed in a series of GMI-ELISA experiments. The findings of these trials indicated that the yield of soluble recombinant GST-rHLT-B could be increased by up to 3-fold, as compared with that seen prior to the optimization, and that lactose was a more efficient alternative inducer than IPTG. The production of rHLT-B, at 92 % purity, reached an optimal level of 96 mg/l in a 3.7 L fermentor. The specific GM1 binding ability of the purified rHLT-B was determined to be almost identical to that of standard CTB.

• BMB Reports
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• v.35 no.2
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• pp.143-154
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• 2002

The structural and functional aspects of ervatamin B were studied in solution. Ervatamin B belongs to the $\alpha+\beta$ class of proteins. The intrinsic fluorescence emission maximum of the enzyme was at 350 nm under neutral conditions, and at 355 nm under denaturing conditions. Between pH 1.0-2.5 the enzyme exists in a partially unfolded state with minimum or no tertiary structure, and no proteolytic activity. At still lower pH, the enzyme regains substantial secondary structure, which is predominantly $\beta$-sheet conformation and shows a strong binding to 8-anilino-1-napthalene-sulfonic acid (ANS). In the presence of salt, the enzyme attains a similar state directly from the native state. Under neutral conditions, the enzyme was stable in urea, while the guanidine hydrochloride (GuHCl) induced equilibrium unfolding was cooperative. The GuHCl induced unfolding transition curves at pH 3.0 and 4.0 were non-coincidental, indicating the presence of intermediates in the unfolding pathway. This was substantiated by strong ANS binding that was observed at low concentrations of GuHCl at both pH 3.0 and 4.0. The urea induced transition curves at pH 3.0 were, however, coincidental, but non-cooperative. This indicates that the different structural units of the enzyme unfold in steps through intermediates. This observation is further supported by two emission maxima in ANS binding assay during urea denaturation. Hence, denaturant induced equilibrium unfolding pathway of ervatamin B, which differs from the acid induced unfolding pathway, is not a simple two-state transition but involves intermediates which probably accumulate at different stages of protein folding and hence adds a new dimension to the unfolding pathway of plant proteases of the papain superfamily.

• BMB Reports
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• v.45 no.8
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• pp.452-457
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• 2012

Diketoreductase (DKR) from Acinetobacter baylyi contains two tryptophan residues at positions 149 and 222. Trp-149 and Trp-222 are located along the entry path of substrate into active site and at the dimer interface of DKR, respectively. Single and double substitutions of these positions were generated to probe the roles of tryptophan residues. After replacing Trp with Ala and Phe, biochemical and biophysical characteristics of the mutants were thoroughly investigated. Enzyme activity and substrate binding affinity of W149A and W149F were remarkably decreased, suggesting that Trp-149 regulates the position of substrate at the binding site. Meanwhile, enzyme activity of W222F was increased by 1.7-fold while W222A was completely inactive. In addition to lower thermostability of Trp-222 mutants, molecular modeling of the mutants revealed that Trp-222 is vital to protein folding and dimerization of the enzyme.

• Bulletin of the Korean Chemical Society
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• v.31 no.10
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• pp.2806-2808
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• 2010

The structure of 3-aminophenol $(CO_2)_1$ cluster was computationally studied both in the ground and the lowest singlet excited electronic states. The ground state structure and binding energy of the cluster was investigated using the second-order M$\ddoot{o}$ller-Plesset perturbation theory (MP2) at the complete basis set (CBS) limit. The excited state geometry of the cluster was obtained at the second-order approximate coupled cluster (CC2) level with cc-pVDZ basis set, and the $S_0-S_1$ absorption spectrum was simulated by calculating Franck-Condon overlap integral. The ground state geometry of the global minimum with a very high binding energy of 4.3 kcal/mol was found for the cluster, due to the interaction between amino group and $CO_2$ in addition to the strong $\pi-\pi$ interaction between the aromatic ring and $CO_2$. The excited state geometry shows a very big shift in the position of $CO_2$ compared to the ground state geometry, which results in low intensity and broad envelope in the Franck-Condon simulation.

• BMB Reports
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• v.36 no.3
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• pp.305-311
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• 2003

A modified actinomycin D was prepared with a hydroxyl group that replaced the amino group at the chromophore 2-position, a substitution known to strongly reduce affinity for double-stranded DNA. Interactions of the modified drug on single-stranded DNAs of the defined sequence were investigated. Competition assays showed that 2-hydroxyactinomycin D has low affinity for two oligonucleotides that have high affinities ($K_a\;=\;5-10{\times}10^6\;M^{-1}$ oligomer) for 7-aminoactinomycin D and actinomycin D. Primer extension inhibition assays performed on several single-stranded DNA templates totaling around 1000 nt in length detected a single high affinity site for 2-hydroxyactinomycin D, while many high affinity binding sites of unmodified actinomycin D were found on the same templates. The sequence selectivity of 2-hydroxyactinomycin D binding is unusually high and approximates the selectivity of restriction endonucleases. Binding appears to require a complex structure, including residues well removed from the polymerase pause site.

• Journal of Electrical Engineering and information Science
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• v.2 no.6
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• pp.106-110
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• 1997

The binding energies of the ground state of both the heavy-hole and light-hole excitons in a GaAs(In\ulcornerGa\ulcornerAs) quantum well sandwiched between two semi-infinite Al\ulcornerGa\ulcornerAs(InP) layers are calculated as a function of well width in the presence of an arbitray magnetic field. A variational approach is followed using very simple trial wave function. The applied magnetic field is assumed to be parallel to the axis of growth and the binding energies are calculated for a finite value of the height of the potential barrier. The exciton binding energies for a given value of the magnetic field are found to be increased than their values in a zero magnetic field due to the compression of their wave functions within the well with the applied magnetic field.