• Macromolecular Research
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• 제15권5호
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• pp.459-464
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• 2007

Polymer electrolyte membranes, featuring ionic channels, were prepared from sulfonated dextran/ poly(vinyl alcohol) (sD/PVA) membranes. A stiff sulfated dextran was chosen as the route for ionic transport, since ionic sites are located along the stiff dextran main chain. The sD/PVA blend membranes were annealed and then chemically crosslinked. The characteristics of the crosslinked sD/PVA membranes were investigated to determine their suitability as proton exchange membranes. The proton conductivity was found to increase with increasing amounts of sD inside the membrane, which reached a maximum and then decreased when the sD content exceeded 30 wt%, while the methanol permeability increased with increasing sD content. The good dispersion of sD inside the membrane, which serves as an ionic channels mimic, played a significant role in proton transportation.

• Journal of Microbiology and Biotechnology
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• 제2권2호
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• pp.135-140
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• 1992

The partitioning of recombinant human interleukin-2(rhII-2) in PEG 8000-dextran 38800 aqueous two-phase system has been investigated using three different sources of rhIL-2. In the case of pure rhIL-2, the solubility in a PEG-dextran two-phase system was low and most of rhIL-2 was partitioned into the bottom phase. For the recovery of rhIL-2 from insoluble protein aggregates, the inclusion bodies of recombinant E. coli were solubilized by the treatment with sodium dodecyl sulfate (SDS). The addition of SDS significantly enhanced not only the solubility of rhIL-2 but also the partitioning of rhIL-2 to the top phase. When the ratio of SDS to rhIL-2 was 2.0, the partition coefficient(K) and the recovery yield(Y) at the top phase were 4.5 and 88%, respectively, at pH 6.8. In order to reduce the recovery steps further, SDS was directly added to the intact recombinant E. coli cells and then partitioned into the PEG/dextran aqueous two-phase system. The observed partition coefficient ($K{\cong{3.0$) and recovery yield ($Y{\geq}80%$ )of this method were comparable to the rhIL-2 recovery from insoluble protein aggregates. The results obtained in this work indicate that PEG-dextran two-phase partitioning might provide a simple way for the recovery and partial purification of recombinant proteins which are produced as inclusion bodies.

• 한국식품저장유통학회지
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• 제31권1호
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• pp.149-160
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• 2024

식물에서 유래하는 전분과 달리 dextran은 미생물 기원으로 바이오폴리머로 glucose 단위체가 α-1,6 결합 형태로 연결된 다당류이며, 주로 젖산균에 의해 설탕으로부터 생산되는 것으로 알려져 있으나 dextran-dextrinase 활성을 갖는 초산균(G. oxydans)을 통해서도 얻을 수 있다. 쌀로부터 dextrin 기반의 dextran을 얻기 위해 쌀 가수분해물을 이용하여 초산균 발효를 통해 dextran을 생산하고 생성물의 특성을 연구하였다. 발효조를 이용한 dextrin 및 쌀 가수분해물 첨가 배지 배양 시, 초산균 배양 20시간 후 모두 OD₆₀₀값 5 수준을 유지하였으며, 배양 72시간 후 상등액의 분자량구성을 GPC 분석한 결과 배지 내 기질의 구성과 달리 DP 480 및 400 수준의 고분자 물질이 생성된 것을 확인하였다. 다당류의 glucose 결합패턴을 ¹H-NMR로 확인한 결과 α-1,4:1,6 결합비율이 각각 1:2.37 및 1:4.4로 증가하여 쌀 가수분해물을 이루는 주요 결합인 α-1,4 결합이 α-1,6 결합 물질로 전환된 것으로 확인되었고, rat 유래 alpha-glucosidase 소화효소 처리결과 glucose가 천천히 방출되는 것으로 나타났다. 이를 통해 쌀 가수분해물은 당전이 활성이 있는 초산균 발효를 통해서 미생물 유래의 dextran으로 전환시켜 수용성 식이섬유 소재와 같이 소화를 지연시키는 고부가 생물소재로 제조할 수 있음을 시사하였다.

• KSBB Journal
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• 제4권1호
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• pp.15-16
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• 1989

Dextran gel 섬유인 Sephadex G gels의 크기를 Ogston-Laurent 의 gel model에 의하여 측정한 결과 섬유의 길이는 $12.48{\times}10^{12}(G-200)$ cm/ ml 범위이고, 섬유의 지름과 partial specific volume은 각각 $7.21{\tiems}10^{-8}cm$와 0.586ml/g이었다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.347-350
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• 2001

The dextran prodution by Leuconostoc mensenteroids NRRL-B512F was studied in a synthetic medium from sucrose as a sole carbon source. Especially, effect of nitrogen source was treated and compared in this study. In oder to maximize the cell growth and dextran produtivity through fermentation two nitrogen sources, yeast extract and tryptone, were used with various concentrations. At the end of fermentation, when the concentration of yeast extract was 9g/L we can obtain the maximum dry cell weight(14.1g/L), dextran dry weight(25.4g/L) and productivity(1.4g/L ${\cdot}$ hr).

• KSBB Journal
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• 제5권4호
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• pp.403-410
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• 1990

Application of the Rheocatch Hotwire Monitoring System for food biotechnology process was evaluated. The growth of microogranism, E coli (JM 83 and Sigma) and Corynesccfertun glutamicum, were monitored. in the fermentor. The cell growth could not be detected the temperature differences between the hotwire and samples($\Delta$T) as indicated by the monitoring system during the fermentation processes. The cell concentration of less than 2g/dl was not sufficient to generate the measurable temperature difference in the fermentor. In order to calibrate the Rheocatch Monitoring System, the temperature difference as a function of solute concentration (microbial cells, sodium cholide, sucrose and dextran) was studied. The relationship between $\Delta$T and the concentration of microbial cells, sucrose and dextran can be expressed in a power series. Further studied with dextran indicated that viscosity and/or kinematic viscosity increase exponentially with an increase in $\Delta$T This is regardless of the concentration and molecular weight of dextran. $\Delta$T linearly increases with the logarithm of molecular weight, while the logarithm of viscosity and the logarithm of kinematic viscosity increase with the logarithm of molecular weight.

• KSBB Journal
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• 제15권6호
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• pp.556-559
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• 2000

Cyclodextrin Glucanotransferase(EC 2.4.1.19 : 1,4-${\alpha}$-glucano) transferase, cyclizing; CGTase) can be separated and recovered in an aqueous two-phase system composed of poly(ethylene glycol)(PEG)/dextran and PEG/salt. In an aqueous two-phase system consisting of PEG 35000 (5%) and dextran T2000 (7%), all cell and debris were collected at the interphase. CGTase partitioned to the denser dextran phase at an yield of 83.4%. On the other hand, in an aqueous two-phase system consisting of PEG 35000 (10%) and sodium phosphate (15%), CGTase partitioned to the denser salt phase at an yield of 95.5%. In order to recover CGTase using an aqueous two-phase system, the PEG/salt system proved to be more efficient than the PEG/dextran system in terms of yield and cost.

• Bulletin of the Korean Chemical Society
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• 제6권4호
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• pp.210-214
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• 1985

Urokinase, a plasminogen activator, was conjugated with dextran by the cyanogen bromide activation-coupling method. The resulting water-soluble conjugate was purified by gel permeation chromatography on Sephadex G-200. The maximal activity was obtained when the ratio of urokinase/dextran was 1/20 for the coupling. The final preparation showed 5 CTA units/mg conjugate, 300 CTA units/mg protein, 8.4 % activity retention, and 47 % protein retention. The urokinase-dextran conjugate had good thermal, pH and storage stabilities. In addition, it showed greater resistance to the inhibitory effect of human plasma than native urokinase. Also in vitro biological half-life of urokinase increased 40 times by this conjugation. In view of activity, excellent stability and increased half-life, the conjugate can be a potential fibrinolytic agent in an injectable form.

• 생명과학회지
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• 제19권4호
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• pp.457-461
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• 2009

본 연구는 Lipomyces starkeyi KCTC 17343에 의한 dextranase 최적 생산 조건을 확립하고 dextran에 대한 효소 분해 특성을 규명하였다. 균주의 성장과 dextranase생산은 발효초기 pH와 온도에 따라 다르며 최적 pH는 4-5, 최적온도는 $25-30^{\circ}C$의 범위에서 결정이 되었다. 최적 발효조건에서의 dextranase 생산은 total enzyme activity가 4.85 IU/ml으로 나타났다. 이때의 발효균주의 specific growth rate는 $0.076h^{-1}$이었다. 발효 중 dextranase의 활성은 발효 정상기에서도 안정성을 유지하였다. Dextranase에 의한 dextran을 가수분해 결과, 가수분해물의 구성은 DP2 to 8에 이르는 올리고 덱스트란으로 이루어졌다.

• 동아시아식생활학회지
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• 제21권1호
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• pp.82-87
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• 2011

김치 원료로부터 덱스트란 생성균과 탁주 효모균이 식혜에 첨가된 설탕을 이용하여 올리고당과 알코올을 생산하는 것을 바탕으로 기능성 알코올 발효 음료 제조를 연구하였다. 식혜 제조를 위한 최대 당화 시간은 가용성 고형물의 변화가 증가한 후 완만하게 되어지는 5시간 내외가 차후 알코올성 발효음료 제조를 위해 적당하였다. 알코올 발효 시 탁주 효모만 사용하였을 경우 약 3%(w/v)가 생성되었으며, 덱스트란 생성균만 접종하였을 경우 알코올 발효는 이루어지지 않았다. 덱스트란생성균과 탁주 효모를 혼합 접종하였을 경우 약 4%(w/v)의 에탄올이 생성되었다. TLC 분석 결과, 탁주 효모만 접종했을 경우 올리고당은 생성되지 않았으며, 탁주 효모와 덱스트란 생성균의 혼합 접종시 설탕을 48시간 안에 사용하였으며, 발효 과정 중 올리고당으로 추정되는 점적을 확인할 수 있었다. 위와 같이 덱스트란 생성균과 탁주 효모를 이용한다면 기능성 올리고당과 알코올을 생성하여 새로운 형태의 기능성 알코올 발효 음료의 생산이 가능할 것으로 보여진다.