• Journal of Microbiology and Biotechnology
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• 제16권6호
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• pp.939-945
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• 2006

The physiological characteristics and function of the exopolysaccharide (EPS) produced by Lactobacillus rhamnosus ATCC 9595 were determined. The total quantity of EPS was rapidly increased to 496$\pm$20 mg/l during the exponential phase, and then maintained steadily during the stationary phase. During the exponential phase (18 h), the total EPS consisted of 61% cell-bound EPS (cb-EPS) and 39% released EPS (r-EPS), whereas the relative proportion of EPS during the stationary phase (48 h) was convered to 23% cb-EPS and 77% r-EPS. On gel permeation chromatography, cb-EPS was fractionated as a single peak of 8.6$\times10^6$ Da, whereas r-EPS was fractionated as two peaks with average molecular weights of 4.3$\times$10$^4$ and 8.6$\times10^6$ Da. Interestingly, both EPS species exhibited anticancer properties and cholera toxin-binding activities. Our results suggest that the EPS generated by L. rhamnosus ATCC 9595 might be suitable for use as a functional food or food supplement.

• Macromolecular Research
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• 제13권2호
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• pp.147-151
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• 2005

The main objective of this study was to modulate pH-sensitive polymers (poly($\beta-amino esters$)) by controlling their molecular weight during their synthesis. These pH-sensitive and biodegradable polymers were synthesized by Michael-type step polymerization. 1,4-Butane diol diacrylate was used as the unsaturated carbonyl compound and piperazine as the nucleophilic compound. Various molecular weight polymers were obtained by varying the mol ratio of piperazine/1,4-butane diol diacrylate. The synthesized polymers were characterized by $^{1}H-NMR$ and their molecular weights were measured by gel permeation chromatography(GPC). The dependence of the molecular weight on the mol ratio was evaluated by the titration method. Also, the pH dependent turbidity of the polymers was determined by UV-Vis spectrophotometry. This pH dependent property of the polymers could be very useful for preparing drug carriers that are sensitive to pH.

• Macromolecular Research
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• 제10권2호
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• pp.85-90
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• 2002

Poly (ethylene oxide)/polylatide/poly(ethylene oxide) (PEO/PL/PEO) tri-block copolymers, which each block is connected by ester bond, were synthesized by coupling reaction of PL with PEO in the presence of pyridine. PL/PEO/PL tri-block copolymer was synthesized by ring opening polymerization of L-lactide initiated by PEO in the presence of stannous octoate. Degradation behavior of the copolymers was investigated in a pH 7.4 phosphate buffer saline (PBS) at 37$\pm$1 $^{\circ}C$. Gel permeation chromatography (GPC) and $^1$H-nuclear magnetic resonance (NMR) were used to monitor the change of mass loss, molecular weight and composition of copolymers. In hydrolytic degradation, the PEO/PL/PEO tri-block copolymer with high PEO contents affected the increase of its mass loss, and resulted in the decrease of its molecular weight as well as PEO composition. However, when PL/PEO/PL and PEO/PL/PEO tri-block copolymers had similar PEO contents, PEO/PL/PEO decreased faster in molecular weight and PEO composition than PL/PEO/PL.

• Macromolecular Research
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• 제15권4호
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• pp.385-391
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• 2007

Block copolymer micelles are generally formed via the self-assembly of amphiphilic block copolymers in an aqueous medium. The hydrophilic and hydrophobic blocks form shell and core micelles, respectively. The block copolymers of methoxy poly(ethylene glycol) (MPEG)-b-poly(2-diisopropylamino)ethyl methacrylate (PDPA) were synthesized via atom transfer radical polymerization, with the macro initiator synthesized by the coupling of 2-bromoisobutyryl bromide with MPEG in the presence of a triethyl amine base catalyst. The atom transfer radical polymerization of 2-diisopropylamino)ethyl methacrylate was performed in conjunction with an N,N,N',N",N"-pentamethyl-diethylenetriamine/copper bromide catalyst system, in DMF, at $70^{\circ}C$. The pH induced micellization/demicellization was studied using fluorescence, with a pyrene probe. Furthermore, the pH dependent micellization was confirmed using the microviscosity method, with a dipyme fluorescence probe. The pH dependant micelle size distribution was studied using dynamic light scattering. The characterization of the synthesized polymers was established using gel permeation chromatography and from the $^1H-nuclear$ magnetic resonance spectroscopy.

• Macromolecular Research
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• 제15권6호
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• pp.541-546
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• 2007

The combination of atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of well-defined block copolymers. Bromo terminated poly(methyl acrylate) (pMA-Br) was prepared by an ATRP initiator, ethyl-2-bromoisobutyrate (EBiB). Subsequently, the bromine chain end of pMA-Br was converted to an azide group by simple nucleophilic substitution reaction. ${\alpha}-Alkyn-{\omega}-bromo-functionalized$ polystyrene was also synthesized by ATRP using the alkyn-functionalized initiator, propargyl-2-bromoisobutyrate (PgBiB). In both cases, the conversion was limited to a low level to ensure a high degree of chain end functionality. Then the coupling reaction between the azide end group in $pMA-N_3$ and alkyn-functionalized PgBiB-pSt was performed by Cu(I)catalysis. This coupling reaction was monitored by gel permeation chromatography (GPC). The synthesized block copolymer was characterized by FT-IR, $^1H-NMR$ spectroscopy and $^1H-^1H$ COSY correlation spectroscopy.

• 한국수산과학회지
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• 제38권4호
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• pp.219-225
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• 2005

We studied the anticancer, antioxidative, ACE inhibitory, antithrombic, and cerebral ischemia inhibitory activities, of low molecular weight substances fractionated from the seasoned and smoked products of skipjack tuna (Euthynus pelamis). Low molecular weight substances fractionated from the liquid extract of seasoned and smoked skipjack tuna powder showed 7 peaks on gel permeation chromatography. Anticancer activity was the highest at Peak 3 $(54.23%)$ followed by Peak 4 $(41.58\%)$. The potency order of antioxidative activity was the highest at Peak 3 $(94.14\%)$ followed by Peak 2 $(82.07\%)$ and Peak 5 $(81.24\%)$. ACE inhibitory activity was the highest at Peak 3 $(67.27\%)$ followed by Peak 5 $(45.62\%)$. But there was weak anti thrombotic effect (PT and APTT) in the low molecular weight substances of the seasoned and smoked products of skipjack tuna. Cerebral ischemia inhibitory activity was the highest at Peak 3 $(80.0\%)$ followed by Peak 5 $(40.0\%)$.

• KSBB Journal
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• 제24권1호
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• pp.59-64
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• 2009

The callus formation from inferior leaf of Aloe saponaria was induced in M & S medium supplemented with 10-30 ${\mu}M$ NAA (${\alpha}$-naphthalene acetic acid) and 3-7 ${\mu}M$ kinetin under incubation in the dark at $25^{\circ}C$ for 6 weeks. The hot water extract ($100^{\circ}C$, 24 hrs) from cultured callus was obtained and the components analysis for the extract were examined to determine the callus can synthesized the bioactive component such as Aloe polysaccharide. The freeze dried extract contained the sugar of 53.2%, protein of 7.3%, ash of 18.5% and water of 21% (w/w). Two fractions (Fr-I and Fr-II) were obtained by Sepharose CL-4B gel permeation chromatography and Fr-I, major fraction was further purified with dialysis. From sugar analysis by TLC and GC, the purified Fr-I fraction consisted of glucose (77.6%), galactose (17.7%), mannose (4.7%, w/w) and uronic acid (trace). The molecular weight of purified Fr-I fraction determined by GPC was about 110 kDa.

• 대한의생명과학회지
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• 제12권4호
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• pp.443-450
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• 2006

To demonstrate their possibilities as an enhanced vaccine delivery system, protein-loaded Poly lactide glycolide copolymer (PLGA) microspheres were prepared with different physical characteristics. Ethyl acetate (EA) solvent extraction process was employed to prepare microspheres and the effects of process parameters on drug release properties were evaluated. The biodeuadability of microspheres was also evaluated by the pH change and GPC (Gel permeation chromatography). Primary IgG antibody responses in BALB/c mice were compared with protein saline solutions as negative controls and adsorbed alum suspensions as positive controls after single subcutaneous injection for in vivo studies. The microspheres showed a erosion with a highly porous structure and did not keep their spherical shape at 45 days and this result could be confirmed by GPC. In vitro release of proteinous drug showed initial burst effect in all batches of microspheres, followed by gradual release over the next 4 weeks. PLGA microspheres were degraded until 45 days and the secondary structure of OVA was not affected by the preparation method. Enzyme-linked immunosorbent assays demonstrated that the single subcutaneous administrations of OVA-loaded PLGA microspheres induced enhanced serum IgG antibody response in comparison to negative and positive controls. These results demonstrated that microspheres providing the controlled release of antigens might be useful in advanced vaccine formulations for the parenteral carrier system.

• BMB Reports
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• 제42권6호
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• pp.387-392
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• 2009

Here, we report the first biochemical and structural characterization of the hypothetical protein HP0902 from Helicobacter pylori, in terms of structural genomics. Gel-permeation chromatography and dynamic light scattering indicated that the protein behaves as a dimer in solution. Circular dichroism spectroscopy showed that HP0902 primarily adopts a $\beta$-structure and the protein was highly thermostable with a denaturing temperature higher than $70^{\circ}C$. Finally, the backbone NMR assignments were obtained on the [$^{13}C,^{15}N$]HP0902 and the secondary structure was determined using the chemical shift data. Additionally, the local flexibility was assessed via a heteronuclear $^1H-^{15}N$ steady state NOE experiment. The results revealed that HP0902 would adopt a compactly folded, all-$\beta$ topology with 11 $\beta$-strands. All of the results clearly support the notion that HP0902 belongs to the cupin superfamily of proteins.

• Bulletin of the Korean Chemical Society
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• 제32권7호
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• pp.2377-2384
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• 2011

Azo-acenaphthylene oligomers with repeating acenaphthylene units "n" up to 4, 5, 7, 17 and 19 have been prepared successfully using nitroxide mediated Stable Free Radical Polymerization (SFRP). Azo-acenaphthylene oligomers, reversibly end-capped by the stable nitroxide 2,2,6,6-tetramethyl-1-piperidinoxyl (TEMPO), were further reacted via radical addition to 4-(naphthalenemethoxy)styrene monomer for diblock co-polymer formation. Characterization of the oligomers and diblock co-polymers was accomplished using MALDI-MS supported by GPC (Gel Permeation Chromatography) and $^1H$ NMR spectrometry. MALDI-MS afforded definitive results by providing an inter-peak interval of 152 (m/z), corresponding to acenaphthylene monomer, and inter-peak interval of 260 (m/z) for the naphthalenemethoxystyrene monomer unit in block copolymers. Our study opens the way to control the number of repeat units in the oligomers. Further these oligomers can be tailored with various monomers for the formation of block copolymers.