• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.946-951
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• 2008

The opd gene, encoding organophosphorus hydrolase (OPH) from Flavobacterium sp. capable of degrading a wide range of organophosphate pesticides, was surface- and intracellular-expressed in Synechococcus PCC7942, a prime example of photoautotrophic cyanobacteria. OPH was displayed on the cyanobacterial cell surface using the truncated ice nucleation protein as an anchoring motif. A minor fraction of OPH was displayed onto the outermost surface of cyanobacterial cells, as verified by immunostaining visualized under confocal laser scanning microscopy and OPH activity analysis; however, a substantial fraction of OPH was buried in the cell wall, as demonstrated by proteinase K and lysozyme treatments. The cyanobacterial outer membrane acts as a substrate (paraoxon) diffusion barrier affecting whole-cell biodegradation efficiency. After freeze-thaw treatment, permeabilized whole cells with intracellular-expressed OPH exhibited 14-fold higher bioconversion efficiency ($V_{max}/K_m$) than that of cells with surface-expressed OPH. As cyanobacteria have simple growth requirements and are inexpensive to maintain, expression of OPH in cyanobacteria may lead to the development of a low-cost and low-maintenance biocatalyst that is useful for detoxification of organophosphate pesticides.

• Journal of Integrative Natural Science
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• v.6 no.4
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• pp.193-196
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• 2013

Haemoglobin is an interesting physiologically significant protein composed of specific functional prosthetic haem and globin moieties. In recent decades, there has been substantial interest in attempting to understand the structural basis and functional diversity of avian haemoglobins (Hbs). Towards this end, purification, crystallization, preliminary X-ray diffraction and molecular-replacement studies have been carried out on Amaurornis phoenicurus Hb. Crystals were grown by the hanging drop vapor-diffusion method using PEG 2000 and NaCl as precipitants. The crystals belonged to the primitive monoclinic system $P2_1$, with unit-cell parameters $a=65.33{\AA}$, $b=93.14{\AA}$, $c=98.54{\AA}$, ${\beta}=100.48^{\circ}$; a complete data set was collected to a resolution of $2.6{\AA}$. The Matthews coefficient of $2.30{\AA}^3Da^{-1}$ for the crystal indicated the presence of two ${\alpha}_2{\beta}_2$ tetramers in the asymmetric unit.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1999.03b
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• pp.173-178
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• 1999

In this study MD simulations have been performed to observe the behavior of a grain boundary in an a-Fe plate under 2-dimensional loading. In MD simulation the acceleration of every molecule can be achieved from the potential energy and the force interacting between each molecule and the integration of the motion equation by using Verlet method gives the displacement of each molecule. Initially four a-Fe rectangular plates having different misorientation angles of grain boundary were modeled by using the Johnson potential and Morse potential We compared the potential energy of the grain boundary system with that of the perfect structure model. Also we could obtain the width of the grain boundary by investigating the local potential energy distribution. The tensile loading for each grain boundary models was applied and the behavior of grin boundary was studied. From this study it was clarified that in the case using Johnson potential the obvious fracture mechanism occurs along the grain boundary in the case of Morse potential the diffusion of the grain boundary appears instead of the grain boundary fracture.

• KSBB Journal
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• v.16 no.4
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• pp.321-326
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• 2001

The change of molecular weight inside and outside a capsule produced using coencapsulating technology was investigated. Chitosan and chitosanase were enveloped in this membrane and product released was a loaded the medium by the principle of size exclusion. The leakage of substrate corresponding to the agitation speed was controlled by adjusting the alginate and CaCO$_3$ concentrations. The optimal condition of alginate concentration and agitation speed were 0.5% and 40rpm, respectively. Membrane thickness and capsules diameter were 10 $\mu$m and approx. 3.0 - 1.5 mm, respectively. Molecular weight difference by concentration and alginate viscosity were of little significance. In accordance with the molecular weight distribution versus enzyme concentration relationship, low concentration of enzyme produced high molecular weight oligosaccharides. At a 1.5 mm capsule size the product diffusion rate to outer surface highest. The molecular weight distribution of the released oligosaccharides was ranged from 1000 to 6000 Da. More than 80% of the initial activity of encapsulated enzyme retained after 8hrs of reaction.

• Bulletin of the Korean Chemical Society
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• v.27 no.9
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• pp.1433-1438
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• 2006

An AsFlFFF channel was designed and built, and then tested for analysis of pullulans and proteins. Pullulans and proteins having various nominal molecular weights were injected at various conditions of the cross-flow rate ($F_c$) and the channel-out flow rate ($F_{out}$). The retention (measured by the retention ratio R) and the zone broadening (measured by the plate height H) were measured, and then compared with theory. When the incoming flow rate, $f_{in}$ (and thus $F_{out}$) was varied with $F_c$ fixed at 2.5 mL/min, the plate height measured for the pullulan with nominal molecular weight (M) of about 100,000 showed the trend expected by the longitudinal diffusion theory (H decreases with increasing flow rate). In contrast, when $F_{out}$ was varied with the flow rate ratio, $F_c/F_{out}$, fixed constant at 5, the plate height measured for the same sample showed the trend expected from the non-equilibrium theory (H increases with increasing flow rate). Calibration plots (log D vs. log M) obtained with pullulans and proteins were not coincide, probably due to the difference in molecular conformation, suggesting the analysis of pullulans and proteins using AsFlFFF requires independent calibration. It was found that the linearity of the protein-calibration plot was improved by using a buffer solution as the carrier.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.3
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• pp.131-138
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• 2002

Thanks to recent progress in availability of molecular and functional techniques it became possible to search for the basic molecular and cellular processes that mediate and control $HCO_3{^-}$ and fluid secretion by the pancreatic duct. The coordinated action of various transporters on the luminal and basolateral membranes of polarized epithelial cells mediates the transepithelial $HCO_3{^-}$ transport, which involves $HCO_3{^-}$ absorption in the resting state and $HCO_3{^-}$ secretion in the stimulated state. The overall process of HCO3 secretion can be divided into two steps. First, $HCO_3{^-}$ in the blood enters the ductal epithelial cells across the basolateral membrane either by simple diffusion in the forms of $CO_2$ and $H_2O$ or by the action of an $Na^+-coupled$ transporter, a $Na^+-HCO_3$ cotranporter (NBC) identified as pNBC1. Subsequently, the cells secrete $HCO_3{^-}$ to the luminal space using at least two $HCO_3{^-}$ exit mechanisms at the luminal membrane. One of the critical transporters needed for all forms of $HCO_3{^-}$ secretion across the luminal membrane is the cystic fibrosis transmembrane conductance regulator (CFTR). In the resting state the pancreatic duct, and probably other $HCO_3{^-}$ secretory epithelia, absorb $HCO_3{^-}.$ Interestingly, CFTR also control this mechanism. In this review, we discuss recent progress in understanding epithelial $HCO_3{^-}$ transport, in particular the nature of the luminal transporters and their regulation by CFTR.

• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.403-409
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• 2005

For transdermal delivery of large molecular drugs such as vaccine and protein drugs, novel microneedle treatment device with roll was designed. The roll dimension is 1.43 cm diameter and 2.8 cm perimeter. Total number of microneedle on the roll is 3,360 with $230\;{\mu}m$ height and $740\;{\mu}m$ distance. The pore with $150\;{\mu}m$ depth and $35\;{\mu}m$ diameter on the skin was made by the designed microneedle device. This system could be achieved without pain. The permeation rates of FITC labelled ovalbumin (FITC-OVA, molecular weight: 45,000 g/mol) as a model protein were determined by modified Franz diffusion cells using skins of hairless mice or SD rats which were treated by using microneedle device two or four times. The average penetration fluxes of model protein increased from 674 to $872\;{\mu}g/cm^{2}{\cdot}hr$ as the number of treatment to make pore increased from two to four times. In conclusion, we confirmed the possibility of using the designed microneedle treatment device for transdermal delivery of the large molecular drugs.

• Food Science of Animal Resources
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• v.31 no.3
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• pp.413-419
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• 2011

The antimicrobial effects of the natural flavonoids kaempferol, quercetin, apigenin, and naringenin as well as a novel flavonoid 7-O-butyl naringenin against the growth of four meat-born Staphylococcus aureus strains were evaluated. First, the flavonoids were screened for inhibitory effects against the growth of each strain using the paper disc diffusion method. Second, the growth inhibitory effects of flavonoids that showed antimicrobial activity were measured using the microplate method. Third, the bactericidal effects of flavonoids were evaluated in a 0.8% (w/v) NaCl solution. All flavonoids showed bacteriostatic effects at >20 mM. Among the flavonoids studied, quercetin was more effective than the others tested. However, the inhibitory effect of 7-O-butyl naringenin on growth of S. aureus KCCM 32395 was greater than that of quercetin at the same concentration. Additionally, 7-O-butyl naringenin exhibited significant bactericidal effects at >25 ${\mu}M$. When bacterial cells were examined using scanning electron microscopy, it appeared that the S. aureus membranes were damaged or morphologically changed when treated with quercetin and 7-O-butyl naringenin at 200 ${\mu}M$.

• 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.

• Bulletin of the Korean Chemical Society
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• v.33 no.1
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• pp.227-232
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• 2012

Galectins are generally believed to be potential candidates for use in the development of novel antiinflammatory agents or as selective modulators of the immune response. In particular, galectin-9 exhibits some of the extracellular functions, including cell aggregation, adhesion, chemoattraction, activation, and apoptosis. Tl-galectin (Tl-gal, galectin-9 homologue gene) was isolated from an adult worm of the Toxascaris leonina. The full-length Tl-gal gene, which was incorporated into pET-28a, was overexpressed in E. coli and purified by nickel affinity and gel filtration chromatographies. The purified Tl-gal was crystallized using the hangingdrop vapor-diffusion method. The crystal belonged to the tetragonal space group $P4_1$, with unit-cell parameters of a = b = $75.7\AA$ and c = $248.4\AA$. The crystals were obtained at $20^{\circ}C$ and diffracted to a resolution of $3.0\AA$. The asymmetric unit contained four molecules of Tl-gal, which gave a crystal volume per protein mass (Vm) of $2.8\AA^3Da^{-1}$ and a solvent content of 54.1%.