• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.43-47
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• 2008

The nickel and cobalt resistance of Cupriavidus metallidurans CH34 is mediated by the CnrCBA efflux pump encoded by the cnrYHXCBAT metal resistance determinant. The products of the three genes cnrYXH transcriptionally regulate expression of cnr. CnrY and CnrX are membrane-bound proteins, probably functioning as anti-sigma factors, whereas CnrH is a cnr-specific extracytoplasmic functions (ECF) sigma factor. The periplasmic domain of CnrX (residues 29-148) was cloned as a N-terminal His-tagged protein, expressed in Escherichia coli, and purified using affinity chromatography and gel filtration. The molecular mass was estimated to be about 13.6kDa by size exclusion chromatography, corresponding to a monomer. The tetragonal bipyramid crystals were obtained by mixing an equal volume of protein in 50mM Tris-HCl, pH 7.5, 1% glycerol, 100mM NaCl, 1mM DTT, and the reservoir solution of 15% w/v PEG 2000, 100mM lithium chloride at 277K in 2-4 days using hanging drop vapor diffusion. The protein concentration was 24mg/ml. The crystal that diffracted to $2.42{\AA}$ resolution belongs to space group $P4_1\;or\;P4_3$ with unit cell parameters of $a=b=32.14{\AA},\;c=195.31{\AA},\;{\alpha}={\beta}={\gamma}=90^{\circ}$, with one molecule of CnrX in the asymmetric unit.

• Journal of Microbiology and Biotechnology
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• v.18 no.1
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• pp.55-58
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• 2008

Alanine racemase, a bacterial enzyme belonging to the fold-type III group of pyridoxal 5'-phosphate (PLP)-dependent enzymes, has been shown to catalyze the interconversion between L- and D-alanine. The alanine racemase from the pathogenic bacterium Enterococcus faecalis v583 has been overexpressed in E. coli and was shown to crystallize an enzyme at 295 K, using polyethylene glycol (PEG) 8000 as a precipitant. X-ray diffraction data to $2.5{\AA}$ has been collected using synchrotron radiation. The crystal is a member of the orthorhombic space group, $C222_1$ with unit cell parameter of a=94.634, b=156.516, $c=147.878{\AA},\;and\;{\alpha}={\beta}={\gamma}=90{\AA}$. Two or three monomers are likely to be present in the asymmetric unit, with a corresponding $V_m\; of\;3.38{\AA}^3\;Da^{-1}\;and\;2.26{\AA}^3\;Da^{-1}$ and a solvent content of 63.7% and 45.5%, respectively.

• Journal of Powder Materials
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• v.23 no.4
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• pp.311-316
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• 2016

$Ni(OH)_2$ hollow spheres have been prepared by solvent displacement crystallization using a micro-injection device, and the effect of process parameters such as concentration and the relative ratio of the injection speed of the precursor solution, which is an aqueous solution of $NiSO_4{\cdot}6H_2O$, to isopropyl alcohol of displacement solvent have been investigated. The crystal phases after NaOH treatment are in the ${\beta}-phase$ for all process parameters. A higher concentration of $NiSO_4{\cdot}6H_2O$ aqueous solution is injected by a micro-injection device and bigger $Ni(OH)_2$ hollow spheres with a narrower particle size distribution are formed. The crystallinity and hardness of the as-obtained powder are so poor that hydrothermal treatment of the as-obtained $Ni(OH)_2$ at $120^{\circ}C$ for 24 h in distilled water is performed in order to greatly improve the crystallinity. It is thought that a relative ratio of the injection speed of $NiSO_4{\cdot}6H_2O$ to that of isopropyl alcohol of at least more than 1 is preferable to synthesize Ni(OH)2 hollow spheres. It is confirmed that this solution-based process is very effective in synthesizing ceramic hollow spheres by simple adjustment of the process parameters such as the concentration and the injection speed.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.805-810
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• 2008

Using metallic Ti powder as raw materials and 1,2-diaminocyclohexane (DACH) as the trial template, two novel reduced titanophosphate open-structures were hydrothermally isolated by varying the $H_3PO_4/H_2O$ ratio to adjust the pH value. TiPO-1 crystallizes in orthorhombic Pbca space group with cell parameters a = 21.956(3) $\AA$, b = 8.6268(11) $\AA$, c = 7.2883(9) $\AA$, V = 1380.5(3) $\AA^3$, Z = 4. TiPO-2 crystallizes in triclinic space group P$\bar{1}$ with parameters a = 5.1620(10) $\AA$, b = 8.815(2) $\AA$, c = 10.655(3) $\AA$, $\alpha$ = $99.45^{\circ}$, $\beta$ = $102.94^{\circ}$, $\gamma$ = $91.06^{\circ}$, V = 465.34 $\AA^3$. TiPO-1 is constructed by infinite -Ti-O-Ti-O- linkage that is capped by $PO_4$ groups to form a chain structure with protonated DACH molecules occupying the interchain spaces. TiPO-2 represents a rare 3-D reduced titanophosphate with 12-MR channels. The structure of TiPO-2 is a neutral framework with water molecules located in the channels.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.18-23
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• 2007

Fe65, a neuron-specific adaptor protein, has two phosphotyrosine binding (PTB) domains. The second PTB (PTB2) domain interacts with intracellular domain fragment (AICD) of amyloid beta precursor protein (APP). Recent studies suggested that tile complex is composed of AICD and Fe65 transactivates genes that are responsible for neuronal cell death in Alzheimer's disease (AD). Therefore, a compound inhibiting the interaction between Fe65 and AICD can be a drug candidate to treat AD. However, it remains unclear how Fe65 recognizes AICD at a molecular level. Here, we report high-level production of the PTB2 domain of Fe65 in the baculovirus system. We found that the baculovirus system is an efficient method to obtain the Fe65 PTB2 domain, compared with the bacterial and mammalian expression systems. The purified recombinant protein was used for crystallization to determine its crystal structure helping to understand the molecular mechanism of Fe65-dependent signaling and to design its inhibitors.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.62-62
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• 2003

The native form of serpin (serine protease inhibitor) is kinetically trapped in metastable state. Metastability in these proteins is critical to their biological function. Serpins inhibit target proteases by forming a stable covalent complex in which the cleaved reactive site loop of the serpin is inserted into $\beta$-sheet A of the serpin with concomitant translocation of the protease to the opposite of the initial binding site. Despite recent determination of the crystal structures of a Michaelis protease-serpin complex as well as a stable covalent complex, details on the kinetic mechanism remain unsolved. In this study we constructed several $\alpha$$_1$-antitrypsin variants and examined their kinetic mechanism of loop translocation and formation of protease-serpin complex by stopped-flow experiments of fluorescence resonance energy transfer as well as quenched-flow experiment. We report here the relationship of serpin's conformational switch mechanism with Inhibitory activity. There is little direct correlation between loop insertion rate and inhibitory activity. Rather, disrupting a salt bridge between R196 and E354 accelerates loop translocation even though it impairs the inhibitory activity. Moreover, the serpin's reactive site loop is translocated, at least partially, prior to loop cleavage.

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1661-1666
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• 2004

The reaction of titanium tetraisopropoxide with 2 equiv of N,N-diethyl acetoacetamide affords Ti($O^iPr)_2(CH_3COCHCONEt_2)_2$ (1) as colorless crystals in 80% yield. Compound 1 is characterized by spectroscopic (Mass and $^1H/^{13}C$ NMR) and microanalytical data. Molecular structure of 1 has been determined by a single crystal X-ray diffraction study, which reveals that it is a monomeric, cis-diisopropoxide and contains a six coordinate Ti(IV) atom with a cis($CONEt_2$), trans($COCH_3$) configuration (1a) in a distorted octahedral environment. Variable-temperature $^1H$ NMR spectra of 1 indicate that it exists as an equilibrium mixture of cis, trans (1a) and cis, cis (1b) isomers in a 0.57 : 0.43 ratio at -20$^{\circ}C$ in toluene-$d_8$ solution. Thermal properties of 1 as a MOCVD precursor for titanium dioxide films have been evaluated by thermal gravimetric analysis and vapor pressure measurement. Thin films of pure anatase titanium dioxide (after annealing above 500$^{\circ}C$ under oxygen) have been grown on Si(100) with precursor 1 in the substrate temperature range of 350- 500$^{\circ}$ using a bubbler-based MOCVD method.

• The Korean Journal of Physiology and Pharmacology
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• v.16 no.3
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• pp.193-198
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• 2012

Changes in the expression profiles of specific proteins leads to serious human diseases, including colitis. The proteomic changes related to colitis and the differential expression between tuberculous (TC) and ulcerative colitis (UC) in colon tissue from colitis patients has not been defined. We therefore performed a proteomic analysis of human TC and UC mucosal tissue. Total protein was obtained from the colon mucosal tissue of normal, TC, and UC patients, and resolved by 2-dimensional electrophoresis (2-DE). The results were analyzed with PDQuest using silver staining. We used matrix-assisted laser desorption ionization time-of-flight/time-of-flight spectrometry (MALDI TOF/TOF) to identify proteins differentially expressed in TC and UC. Of the over 1,000 proteins isolated, three in TC tissue and two in UC tissue displayed altered expression when compared to normal tissue. Moreover, two proteins were differentially expressed in a comparative analysis between TC and UC. These were identified as mutant ${\beta}$-actin, ${\alpha}$-enolase and Charcot-Leyden crystal protein. In particular, the expression of ${\alpha}$-enolase was significantly greater in TC compared with normal tissue, but decreased in comparison to UC, implying that ${\alpha}$-enolase may represent a biomarker for differential diagnosis of TC and UC. This study therefore provides a valuable resource for the molecular and diagnostic analysis of human colitis.

• Bulletin of the Korean Chemical Society
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• v.15 no.10
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• pp.891-896
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• 1994

Reactions of mer, trans-$Re({\equiv}NC_6H_5)(PPh_3)_2Cl_3$, I, with $PMe_3$ and $P(OMe)_34 at room temperature, led to mer, trans-$Re({\equiv}NC_6H_5)(PPh_3)(PMe_3)Cl_3$, II, and fac-$Re({\equiv}NC_6H_5)(PPh_3)(P(OMe)_3)Cl_34, III, respectively. The crystal structures of II and III were determined through X-ray diffraction. Ⅱ crystallizes in the orthorhombic system, space group $Pna2_1$ with cell parameters a=19.379(4) ${\AA}$, b=11.867(2) ${\AA}$, c = 12.676(3) ${\AA}$, and Z = 4. Least-squares refinement of the structure led to a $R(wR_2)$ factor of 0.0251 (0.0621) for 2203 unique reflections of $I>2{\sigma}(I)$ and for 306 variables. III crystallizes in the monoclinic system, space group $P2_1/n$ with cell parameters a=11.399(3) ${\AA}$, b=14.718(4) ${\AA}$, c=17.558(5) ${\AA}$, ${\beta}=97.79(2){\circ}$, and Z=4. Least-squares refinement of the structure led to a $R(wR_2)$ factor of 0.0571 (0.1384) for 3739 unique reflections of $I>2{\sigma}(I)$ and for 344 variables. Structural studies showed that the relative orientations of the two phosphines in both complexes are different, probably due to the differences in the coordinating abilities between $PMe_3$ and $P(OMe)_3$ to the 5-coordinate fluxional intermediate.

• Bulletin of the Korean Chemical Society
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• v.15 no.11
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• pp.990-996
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• 1994

New ferrocene-based chelate amines, $Fe[C_5H_4CH(Me)NMe_2]_2\;(3), \;Fe[C_5H-3(CH(Me)NMe_2)(PPh_2)-1,2]_2\;(4),\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(CN)NMe_2-1,2)\;(6),\;and\;(C_5H_5)Fe(C_5H_3(CH_2NMe_2)(CH(Me)NMe_2-1,2)$ (7) have been prepared. The reaction and the coordination chemistry of 4 and other related compounds (S,R)-(1-N,N-dimethylaminoethyl)-2-dicyclohexylphosphino)ferrocene (CPFA) and 1,1'-bis-(diphenylphosphino)ferrocene (BPPF) with $Rh_2(OAc)_4(MeOH)_2$ were investigated. The reaction of the chiral ligand (S,R)-CPFA forms a complex of the type (${\eta}^1$-(S,R)-CPFA-P)$_2Rh_2(OAc)_4$ (8) in which the ligand is coordinated to both rhodium centers in a monodentate fashion through phosphorus. In contrast, the bisphosphine analogues such as BPPF and 4 afford chelate complexes of the type (${\eta}^2-PP)Rh_2(OAc)_4$ (9 & 10) where both ligands act as a chelate bidentate to a single rhodium atom. All these complexes were characterized by microanalytical and spectroscopic techniques. In one case, the structure of 8 was determined by X-ray crystallography. Crystals are monoclinic, space group C2 (No. 5), with a=26.389 (3), b=12.942 (1), c=11.825 (1) A, ${\beta}$=111.22(1)$^{\circ}$, V=3964.7 (8) $A^3$, Z=4, and $D_{calc}$=1.58 g $cm^{-3}$. Two Rh(II) centers are bridged by four $AcO^-$ groups in the ${\eta}^1$ : ${\eta}^1$ mode across a Rh-Rh single bond, and octahedral coordination at Rh(1) and Rh(1') is completed by axially coordinating (S,R)-CPFA and a briding $AcO^-$, respectively.