• Fisheries and Aquatic Sciences
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• 제2권2호
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• pp.149-154
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• 1999

Response Surface Methodology was applied for optimizing the processing parameters of ultrasound treatment in order to produce low-molecular alginate. The use of ultrasound significantly reduced viscosity of alginate solutions. Suggested parameters of ultrasound treatment for maximum reduction of alginate molecular weight were: specific intensity, 115.81 $W/cm^2$ at 20kHz frequency; treatment time, 35.55 min; temperature, $20.08^{\circ}C$; alginate concentration, $2.5\%$. Low-molecular alginate obtained by ultrasound had two peaks on Sepharose CL-6B gel filtration. The viscosities of control, fraction I, and fraction II at $0.1\%$ concentration and $25^{\circ}C$ were 3.07, 1.23, and 0.82cps, respectively. Molecular weights of control, fraction I, and fraction II alginates were 336,500, 70,400, and 52,800 daltons, and their solubilities were 3, 6, and $14\%$, respectively. The lower molecular weight of alginate, the lower the alcohol precipitation and the higher $Ca^{2+}$ ion binding capacities. Heavy metal ion binding capacities of alginates were high in the following order of Pb, Cd, Zn, and Co.

• 한국식품과학회지
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• 제33권1호
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• pp.122-127
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• 2001

잔나비버섯 자실체로부터 열수추출하여 얻어진 고분자 및 저분자 분획의 이화학적 특성 및 생리활성 대하여 검토하였다. 고분자와 저분자 분획은 당과 단백질 및 소량의 hexosamine을 함유하고 있었다. 구성 당은 주로 glucose, galactose, mannose와 소량의 xylose, fructose, ribose 및 arabinose 등으로 구성되었으며, 아미노산의 경우는 당과 단백질의 결합력에 관여하고 있는 Ser과 Thr를 다량 함유하고 있는 것으로 조사되었다. 고분자 분획의 분자량은 10 kD 부근에서 주를 이루고 있는 것으로 나타났다. 항보체활성은 고분자 분획에서 높았으며, 항체생성능은 대조군에 비해 약간 증가하는 양상을 나타내었다. 탐식능, NO 및 $TNF-{\alpha}$ 생성능은 서로 상관성이 있는 것으로 조사되었다. 효소적 및 비효소적 지질과산화 유발에 대한 영향은 고분자 및 저분자 분획에서 모두 억제능을 나타내었다. 이와 같이 잔나비버섯 자실체로부터 추출한 고분자 및 저분자 분획은 면역활성 및 지질 과산화 억제효과 있는 것으로 조사되었다.

• 한국식품영양과학회지
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• 제13권3호
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• pp.326-333
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• 1984

The oxidation rate of krill lipids is very slow and no peroxides are accumulated even after long storage. By means of various chromatographic techniques and mass spectrophotometry, the primary antioxidant has been identified as ${\alpha}$-tocopherol. The phospholipid fractions did not show any antioxidative activity but peroxide-decomposing properties of total lipids depended upon the phospholipid contents. The peroxide-decomposing activities of phospholipids were due to the presence of polar materials generated during the storage. The most peroxide-decomposing fractions of oxidized krill lecithin by DEAE-cellulose column chromatography was low-molecule fraction (mean molecular weight: 182) and high-molecule fraction (mean molecular weight: 1942) was the next. The separation of peroxide-decomposing properties from low-molecule fraction was achieved by partitioning between chloroform and methanol/water. The methanol/water fraction showed strong peroxide-decomposing activities and main component of this fraction was assumed hydroxyamine compounds derived from choline.

• 한국수산과학회지
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• 제44권6호
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• pp.630-634
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• 2011

Enzymatic hydrolysate of porphyran from Porphyra yezoensis was prepared by treatment with ${\beta}$-agarase. The hydrolysate was fractioned into molecular sizes of <3, 3-30, and 30-300 kDa using an ultrafiltration membrane. The membrane fractions were further separated into neutral and anionic fractions using Dowex $1{\times}8$ ion exchange chromatography. After hydrolysis of porphyran with ${\beta}$-agarase, 23.2% of the starting porphyran was recovered as a neutral fraction of low-molecular weight (<3 kDa), and 28.9% remained as an enzyme-resistant anionic fraction of high molecular weight (>300 kDa). Desulfation of porphyran and $^{13}C$-NMR analysis of the anionic fraction of low molecular weight (<3 kDa) showed that the anionic fraction has a backbone consisting of 3-linked ${\beta}$-D-galactose units alternating with either 4-linked a-L-galactose 6-sulfate or 3, 6-anhydro-a-L-galactose units. These results indicate that porphryan is a copolymer of two moieties, about 25% of which are composed of neoagarose moieties and 75% as anionic moieties.

• 생명과학회지
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• 제5권3호
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• pp.117-120
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• 1995

Human milk was examined for antiangiogenic activities by using the chick embryo chorioallantoic membrane (CAM) assay and endothelial cell growth. The low molecular weight (20 KD>$\sim$ ) fraction of human milk stimulated the angiogenesis and increased the endothelial cell growth. These results suggest that the increase of angiogenesis and endothelial cell growth might be attributed to several growth factors and/or angiogenic factors in low molecular fraction (20 KD>$\sim$) of human milk.

• 한국대기환경학회지
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• 제23권2호
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• pp.242-249
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• 2007

Deposition fluxes of polycyclic aromatic hydrocarbons (PAHs) were measured at the Chonbuk National University located in Jeonju between June and November 2002. Fluxes of gaseous and particulate PAHs were separately obtained using a water surface sampler (WSS) and a dry deposition plate (DDP). Most of PAHs were deposited in the gaseous form since the low molecular weight PAHs dominates in the atmosphere. The deposition velocity of particulate PAHs was higher than that of gaseous PAHs when the molecular weight was low, but substantially decreased as the fine particle fraction increased with molecular weight. The deposition velocity was generally higher at high wind speeds. However, increase in the deposition velocity in unstable atmospheric conditions was also observed for gaseous PAHs of intermediate molecular weight.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3340-3344
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• 2013

The fabrication of polymer field-effect transistors with good electrical properties requires the minimization of molecular defects caused by low molecular weight (MW) fractions of a conjugated polymer. Here we report that the electrical properties of a narrow bandgap conjugated polymer could be dramatically improved as a result of dipping a thin film into a poor solvent. The dipping time in hexanes was controlled to efficiently eliminate the low molecular weight fractions and concomitantly improve the molecular ordering of the conjugated polymer. The correlation between the structural order and the electrical properties was used to optimize the dipping time and investigate the effects of the low MW fraction on the electrical properties of the resulting thin film.

• The Korean Journal of Ecology
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• 제24권1호
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• pp.35-43
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• 2001

카드뮴과 아연에 각각 그리고 동시에 노출한 총알고둥(Littorina brevicula)에서 중금속의 생체내 축적, 제거 및 세포내 분포 양상을 조사하였다. 총알고둥을 카드뮴 400 $\mu\textrm{g}$/L 또는 아연 3000 $\mu\textrm{g}$/L에 각각 90일간 노출하였을 경우, 각 중금속의 축적량은 노출기간에 따라 증가하였으며, 70일 이후에는 더 이상 축적량이 증가하지 않았다. 카드뮴과 아연을 동시에 노출하였을 경우에는 각각의 중금속에 노출하였을 경우에 비해 아연의 축적량은 증가하였으나, 카드뮴의 축적량은 감소하였다. 노출실험에 이어 수행한 42일간의 청장실험 결과, 카드뮴은 체외로 제거되지 않았으나, 아연은 제거되었다. 특히 카드뮴과 아연에 동시 노출한 총알고둥의 경우에 아연은 더 신속히 제거되었다. 총알고둥을 카드뮴과 아연에 각각 70일 동안 노출한 후, 체내로 흡수된 카드뮴의 약 60%가 soluble fraction에 분포하고 있었으며, 아연의 75%는 insoluble fraction에 분포하고 있었다. 이러한 경향은 카드뮴과 아연의 동시 노출시에도 유사하게 나타났다. 카드뮴과 아연은 soluble part내의 리간드(ligand) 와의 결합 양상에서도 차이를 나타냈는데, 카드뮴은 90% 이상이 약 6.5 kDa크기의 MBP-1(Metal-Binding Protein-1)과 결합하고 있었으나, 아연은 HMW(High molecular weight fraction, >60 kDa), MBP-1, MBP-2, LMW(Low molecular weight fraction <1 kDa)에 고루 분포하는 것으로 나타났다.

• 산업기술연구
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• 제17권
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• pp.297-303
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• 1997

This study investigates the characteristics of humic acid before and after ozonation. The results were comapred in such terms as CODCr, CODMn, TOC(total organic carbon) and molecular size distribution. As a result of ozonation (with the dose of 3mgO3/mgHumic Acid), UV NIS absorbance, CODCr, CODMn and TOC were decreased with similar tendency. The mole fraction of high molecular size was rapidly decreased and the fraction ratio of low molecular size was increased through ozone treatment. This fact can be correlated with the change in the difference and the ratio of CODCr and CODMn (the value of CODCr-CODMn and CODMn/CODCr). From this result, it can be inferred that the molecular size and the degree of chemical oxidative degradation of humic acid after ozonation were changed.

• 한국식품영양과학회지
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• 제24권5호
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• pp.651-657
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• 1995

모유성분을 고분자분획(20KD 이상 분자)과 저분자분획(20KD 이하 분자)으로 나누어 항산화력을 검토한 결과, 고분자분획이 저분자분획 보다 더 강력한 항산화력을 나타내었다. 이 모유의 항산화력은 주로 20KD 이상에 존재하는 항산화 효소에 기인할 가능성이 시사되어 모유의 채유 기간에 따른 항산화 효소를 비롯하여 protein-SH와 nonprotein-SH를 검토한 결과, catatase는 7일째 현저히 저하한데 비해 GSH peroxidase, GSH S-transferase는 7일째를 전후로 현저히 증가한 후 감소하는 경향을 나타내었다. Protein-SH는 채유 기간에 따라 차츰 감소하였으나 nonprotein-SH는 20일째 peak를 이루고 그 후 감소하였다. 이상의 결과로 부터 모유의 고분자분획은 강력한 항산화력을 나타내었으며, 이 항산화력은 catalase, GSH peroxidase 및 GSH S-transferase 등의 항산화 효소 활성에 기인할 것으로 사료된다.