• Archives of Pharmacal Research
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• 제4권1호
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• pp.33-41
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• 1981

The prepared dextran sulfates were characterized by measuring the reduced viscosisty at five different concentrations to obtain an intrinsic viscosity in both phosphate and tris buffers, pH 7.4, ionic strength of 0.1 Dextran sulfates having 0.81, 1.06 sulfate groups per hexose unit have reduced viscosity value below 40 ml/g whereas dextran sulfates having 1.21, 1.43, 1.69 sulfate groups per hexose unit have reduced viscosity value over 40 ml/g. Dextran sulfate having 1.21 sulfate groups per hexose unit had highest value of reduced viscosity. The reduced viscosity of dextran sulfate in tris buffer was always higher than that in phosphate buffer regardless of the sulfate content of dextran sulfate. The influence of the sulfation of the dextran sulfate. The influence of the sulfation of the dextran sulfate molecule on the dextran sulfate-LDL interaction was studied with three different dextran sulfate molecules. Dextran sulfate molecules having more than one sulfate group per hexose unit. The dextran sulfate having 0.81 sulfate groups per hexose unit showed considerably different precipitation curves in phosphate and tris buffers. This peculiar behavior of dextran sulfate having 0.81 sulfate groups per hexose unit in the two buffer systems was not noticed with dextran sulfate having more than one noticed with dextran sulfate having more than one sulfate group per hexose unit.

• KSBB Journal
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• 제9권1호
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• pp.1-7
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• 1994

본 연구에서는 dextransucrase의 효소반응에 의한 dextran 생성기작을 규명하고자 하였다. Dextransucrase에 의한 dextran 생성은 초기당농도 50~150g/$\ell$에 대하여 수행하였고 생성된 dextran은 GPC를 사용하여 분자량 분포를 측정하였다. 이 연구에서 실험한 surcrose 농도범위에서는 surcrose가 primer로 작용하지 않은 것으로 추측된다. 또한 surcrose 농도가 50~100g/$\ell$의 범위에서 확산에의한 surcrose의 물질전달 제약에 의한 중합속도의 감소로 먼저 중간분자량 dextran이 생성되었다가 고분자량 dextran이 생성된다는 것을 알 수 있었다. Surcrose 농도가 100~150g/$\ell$로 증가하면서 중간분자량 dextran 생성기작은 라디칼 중합반응을 따르나 낮은 surcrose 농도에서는 물질전달 제약에 의하여 중합반응속도가 감소되어 중간분자량의 dextran을 생성함을 알 수 있었다.

• KSBB Journal
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• 제10권3호
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• pp.257-263
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• 1995

본 연구는 비용매첨가법에 의한 "native" dextran 의 분별침전에 관한 내용으로, 첫째, 유전상수값이 다른 비용매들에 의한 dextran의 침전 특성을 조사 하였다. 둘째. dextran생산에셔 분별침전 과정의 방 법적 인 개선을 시도하였다. 침전특성을 조샤한 결과, 침전된 dextran은 비용매 함량과 일차함수관계를 보였고, 그 일차식의 가울기는 비용매의 유전상수값 과 상관관계를 보이므로서. dextran의 침전을 유도 하는 주요특성이 비용매의 유전상수임을 알았다. 그 리고 재분별에 의한 침전방법을 원용하여 dextran 의 분별침전 과정을 구성하였으며, dextran의 침전 특성 결과와 조합하여 일정한 분자량 빛 분자량 분 포를 갖는 dextran을 효율적으로 생산할 수 였는 근거를 마련하였다.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2005년도 생물공학의 동향(XVII)
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• pp.358-362
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• 2005

High molecular weight dextran (39% alcohol, v/v), less soluble dextran, eluted from this column between T 500 and T 2000, a commercial linear dextran, Soluble dextran (45% alcohol, v/v) eluted at between T 70 and T 150 dextran. The molecular weight average of total dextran (50% alcohol, v/v) was between 150,000 to 500,000. A few oligosaccharides were detected from hydrolyzates of less soluble dextran. The hydrolyzates of soluble dextran were a family of DP 1 to 6 isomaltooligosaccharides. Compounds greater than DP 4 were branched isomaltooligosaacharides.

• 한국미생물·생명공학회지
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• 제20권3호
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• pp.316-323
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• 1992

가자미 식해에서 분리한 Leuconostoc mesenteroides(Sikhae)로부터 생산한 dextransucrase 조효소액에 10 sucrose를 반응시켜 얻은 dextran 생성액의 유변성과 생성된 dextran의 분자량 분포 및 수율을 반응시간별로 조사하였다. Dextran 생성속도는 반응액의 HPLC를 이용한 당분석과 점도측정으로 추정이 가능하였다. Periodate oxidation 시험결과 정제된 dextran은 89의 Alpha-(1-6) 결합외에 11의 Alpha-(1-3) 부결합이 존재하는 것으로 판단되며, 반응시간이 경과함에 따라 dextran 생성액은 높은 항복력을 갖는 Bingham-pseudoplastic 유체특성을 나타내었다. 반응시간이 결과함에 따라 시간의존 특성(thixothropicity)이 증가하였는데 이러한 현상은 GPC 분석을 통하여 dextran 생성액내 고분자 dextran의 비율증가에 의한 것임을 알 수 있었다. Dextran 생성액은 반응 8시간후에 최고점도 (2680 cP. $\gamma$=$33.75s^{-1}$, $25^{\circ}C$)를 나타내었으며, 그 이후부터 점도는 다시 감소하였다. 또한 dextran 생성액은 온도가 증가함에 따라 점도가 감소하였으며, 이는 Arrhenius의 일반식으로 표시할 수 있었다. Arrhenius 식으로 구한 dextran 생성액의 유동 활성화에너지는 반응시간이 경과함에 따라 증가하였으며, 8시간 반응시킨 dextran 생성액의 경우 1.69kcal/gmole 정도로써 온도증가에 의한 점도변화가 비교적 적음알 수 있었다.

• 한국미생물·생명공학회지
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• 제20권2호
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• pp.190-195
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• 1992

Polythylene glycol/dextran 수성 2단계에서 polyethylene glycol의분자량과 농도가 증가할수록 체적비는 증가하고 분배계수는 감소하였다. 또한 dextran의 분자량이 증가할 수록 체적비는 감소하고 분배계수는 증가하였다. 한편 dextran의 농도가 증가할수록 체적비와 분배계수는 감소하였다.

• Journal of Pharmaceutical Investigation
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• 제37권1호
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• pp.45-49
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• 2007

Dextran-5-aminosalicylic acid conjugate (dextran-5-ASA) was in vitro-evaluated as a polymeric colon-spe-cific prodrug of 5-aminosalicylic acid (5-ASA). Chemical stability of dextran-5-ASA in the pH 1.2 or 6.8 buffer solutions was investigated at 37 for 6 hrs. The dextran backbone was not degraded and no 5-ASA release was detected. Moreover, dextran-5-ASA neither liberated 5-ASA in the homogenates of the small intestine of rats nor was transported across Caco-2 cell monolayers, suggesting no significant loss of dextran-5-ASA during transit through the upper intestine. Furthermore, incubation of dextran-5-ASA in 10% cecal contents of rats released about 37% and 55% of 5-ASA bound to dextran in 8 hr and 24 hr, respectively. While that with either esterase or dextranase failed to liberate 5-ASA from the polymeric prodrug, incubation of dextran-5-ASA with both esterases and dextranse released 5-ASA up to about 24% of 5-ASA bound to dextran. These results suggest that, after oral administration of dextran-5-ASA, the polymeric prodrug is delivered specifically to and releases 5-ASA in the large intestine, and reveal that the 5-ASA release by cleavage of the ester bond requires precedent depolymerization of the dextran backbone.

• Geomechanics and Engineering
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• 제12권5호
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• pp.849-862
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• 2017

With growing interests in using bacterial biopolymers in geotechnical practices, identifying mechanical properties of soft gel-like biopolymers is important in predicting their efficacy in soil modification and treatment. As one of the promising candidates, dextran was found to be produced by Leuconostoc mesenteroides. The model bacteria utilize sucrose as working material and synthesize both soluble and insoluble dextran which forms a complex and inhomogeneous polymer network. However, the traditional rheometer has a limitation to capture in situ properties of inherently porous and inhomogeneous biopolymers. Therefore, we used the particle tracking microrheology to characterize the material properties of the dextran polymer. TEM images revealed a range of pore size mostly less than $20{\mu}m$, showing large pores > $2{\mu}m$ and small pores within the solid matrix whose sizes are less than $1{\mu}m$. Microrheology data showed two distinct regimes in the bacterial dextran, purely viscous pore region of soluble dextran and viscoelastic region of the solid part of insoluble dextran matrix. Diffusive beads represented the soluble dextran dissolved in an aqueous phase, of which viscosity was three times higher than the growth medium viscosity. The local properties of the insoluble dextran were extracted from the results of the minimally moving beads embedded in the dextran matrix or trapped in small pores. At high frequency (${\omega}>0.2Hz$), the insoluble dextran showed the elastic behavior with the storage modulus of ~0.1 Pa. As frequency decreased, the insoluble dextran matrix exhibited the viscoelastic behavior with the decreasing storage modulus in the range of ${\sim}0.1-10^{-3}Pa$ and the increasing loss modulus in the range of ${\sim}10^{-4}-1\;Pa$. The obtained results provide a compilation of frequency-dependent rheological or viscoelastic properties of soft gel-like porous biopolymers at the particular conditions where soil bacteria produce bacterial biopolymers in subsurface.

• Journal of Microbiology and Biotechnology
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• 제16권8호
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• pp.1316-1319
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• 2006

An antibody displayed phage collection (SBAE-2R), screened from a human synthetic phage antibody library (Fab 21ox), was used for the determination of dextran. The dextran-binding affinity was determined by serologically specific transmission electron microscopy (TEM) and a paper dipstick assay. The phage collection was distributed over the dextrancoated grids with 39$\pm$25 phages/$\mu$m$^2$ on the grids. Phages were not seen on dextran-coated grids exposed to the Fab 2lox phage library. The phage collection (SBAE-2R) produced 54$\pm$3 color normalized intensity (N.I.) from 125 ppm to 1,000 ppm of dextran and 5$\pm$1 (N.I.) for 63 ppm of dextran in a paper dipstick assay. This research extends the analytical options for dextran analysis by antibody displayed phage with a minimum of equipment usage.

• 한국의류학회지
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• 제28권11호
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• pp.1507-1515
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• 2004

Washable wool was developed using environmental-friendly spray UV-cure technique. Photocrosslinkable polymer, dextran-methacrylate, was synthesized starting from natural biopolymer, dextran. The aqueous solution of dextran-methacrylate was applied to wool fabric with various concentrations to find out the optimum condition in minimizing felting shrinkage. The wool fabric subsequently cured by 365 nm UV, The effects of UV-cure time and photoinitiator concentration on felting behavior of wool were examined. As the concentration of dextran-methacrylate increased, the felting shrinkage decreased gradually. At concentration 0.5g/ml, the felting shrinkage of wool was negligible. Other properties such as air permeability, moisture content, wrinkle recovery, thickness and wettability were also evaluated. The surface coating of dextran polymer onto wool fiber was identified by SEM.