• 한국수산과학회지
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• 제37권5호
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• pp.359-365
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• 2004

To study the lipid adsorption characteristic of chitosans with different molecular weights and the degrees of deacetylation, in vitro test and near-infrared (NIR) spectroscopic analysis have been performed for the measurement of lipid adsorption characteristics of chitosan. The degrees of deacetylation in chitosans were $70{\%},\;85{\%}\;and\;92{\%}$ at different deacetylation times (1 hr, 2 hrs, 3 hrs), respectively. The molecular weight of each chitosan was controlled by enzymatic hydrolysis, and then the molecular weight of the chitosan was 4 kDa. The bulk density, water holding capacity and fat binding capacity of each chitosan powder were $96.2-504.0{\%},\;374.4-1217.9{\%},\;and\;307.0-659.3{\%}$, respectively. The higher molecular weight of chitosan was exhibited the lower bulk density and the higher water and fat binding capacities. Bindinf capacities of chitosan powders to bile salts, cholesterol and linoleic acid were $41.2-63.3{\%},\;40.8-67.4{\%},\;42.6-72.6{\%}$, respectively. In NIR spectrum of lipid adsorbed chitosan the occurrence static eletronical binding between chitosan and lipid was identified by NIR spectrum peak induced from combination of carboxylic group in lipid and amino group in chitosan. In conclusion, the higher degree of deacetylation and molecular weight of chitosan showed the higher lipid binding capacity and the lipid adsorption of chitosan were occurred by combination of carboxylic group in lipids and amino group in chitosan.

• 한국식품과학회지
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• 제44권4호
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• pp.460-466
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• 2012

T-2와 HT-2 독소는 type A trichothecene계 곰팡이독소에 속하는 식품 오염물질이나, 국내의 경우 기준치 설정과 분석법의 확립이 요구되고 있다. 본 연구에서는 T-2와 HT-2 독소의 분석법 확립에 도움이 되고자 옥수수와 현미 시료에 존재하는 carboxylesterase에 의한 T-2 독소의 탈아세틸화가 GC 및 HPLC에 의한 T-2와 HT-2 독소 분석치에 미치는 영향을 살펴보았다. 옥수수와 현미 시료로부터 제조된 carboxylesterase 조효소원에 의한 T-2 독소의 HT-2 독소로의 전환 정도를 살펴본 결과, 15분 이내에 84-86%의 HT-2 독소가 급격히 형성되었고, 30분 이후에는 93-95%로 증가한 후 일정하게 유지되었다. 시료에 존재하는 효소의 불활성화 여부가 분석치에 미치는 영향을 살펴보면, 효소를 불활성화 시킨 시료에서는 T-2 독소가 60-107% 검출되었고 HT-2 독소가 검출되지 않은 반면, 효소를 불활성화 시키지 않은 시료에서는 T-2 독소가 0-9% 검출되었고 HT-2 독소가 77-121% 생성되었다. 추출용매 및 추출방법에 따른 T-2 독소의 탈아세틸화를 살펴본 결과, methanol/water 80:20으로 추출한 경우에는 T-2 독소가 84-108% 검출되었다. 곰팡이독소의 동시분석을 위해 PBS로 1차 추출한 다음 methanol로 추출할 때, 효소를 불활성화 시킨 시료에서는 T-2 독소가 60-87% 검출되었고 HT-2 독소가 검출되지 않았다. 반면, 효소를 불활성화 시키지 않은 시료에서는 T-2 독소가 검출되지 않았고 HT-2 독소가 37-66% 생성되었다. 이러한 결과는 옥수수와 현미 시료에 존재하는 carboxylesterase에 의해 T-2 독소가 탈아세틸화되어 T-2와 HT-2 독소를 각각 정량분석할 때 분석치에 영향을 미칠 수 있다는 것을 시사한다.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.1
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• pp.129-136
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• 2006

Although cleaner and cheaper deinking of ONP could be performed at the neutral or low alkaline condition excessive loss from froth-flotation is unavoidable and so reduction of alkali or caustic soda dosage sacrifices recycling yield. Now the new trade-off regarding alkali dosage versus flotation yield is urgently required in order to set the optimized neutral or low alkaline deinking process of ONP. Lipase from Thermomyces Lanuginosus has an effect on desizing and deacetylation reaction and it could be applied to the stock of pre flotation secondary stage in order to reduce the flotation reject without the sacrifice of optical properties of flotation accepts. Instead of inorganic base, lipase could be applied as a biochemical catalyst for the selective modification of valuable hydrophobic particles in deinking stock, for example cellulose fines and inorganic fillers covered by hydrophobic additives or contaminants. When the enzymatic hydrolysis of ester bond could be made on the surface of hydrophobic particulates, unwanted float of fine particles could be prevented. Now the enhancement of flotation selectivity or the modification of the hydrophobicity of deinking stock is expected to be promoted by the enzymatic pre treatment. And the reduction of recycling cost with the saves of raw material, recovered paper would be possible as a result.

• Biotechnology and Bioprocess Engineering:BBE
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• 제6권1호
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• pp.18-24
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• 2001

The advantage of using Streptomyces griseus HUT 6037 in the production of chitinase or chitosanase is that the organism is capable of hydrolyzing amorphous or crystalline chitin and chitosan according to the type of the substrate used. We investigated the effects of the enzyme induction time and chitin sources, CM-chitosan and deacetylated chitosan (degree of deacetylation 75-99%), on production of chitosanase. We found that this strain accumulated chitosanase when cells were grown in the culture medium containing chitosanaceous substrates instead of chitinaceous substrates. The highest chitosanase activity was obtained at 4 dyas of cultivation with 99% deacetylated chitosan. The specific activities of chitinase and chitosanase were 0.91 and 1.33 U/mg protein at 3 and 5 days, respectively. From the study of the enzymatic digestibility of various degrees of deacetylated chitosan, it was found that (GlcN)$_3$, (GlcN)$_4$and (GlcN)(sub)5 were produced during the enzymatic hydrolysis reaction. The results of this study suggested that the sugar composition of (GlcN)$_3$was homogeneous and those of (GlcN)$_4$and (GlcN)(sub)5 were heterogeneous.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.759-766
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• 2008

Among more than a hundred colonies of fungi isolated from soil samples, DY-52 has been screened as an extracellular chitin deacetylase (CDA) producer. The isolate was further identified as Mortierella sp., based on the morphological properties and the nucleotide sequence of its 18S rRNA gene. The fungus exhibited maximal growth in yeast peptone glucose (YPD) liquid medium containing 2% of glucose at pH 5.0 and $28^{\circ}C$ with 150 rpm. The CDA activity of DY-52 was maximal (20 U/mg) on the 3rd day of culture in the same medium. The CDA was inducible by addition of glucose and chitin. The enzyme contained two isoforms of molecular mass 50 kDa and 59 kDa. This enzyme showed a maximal activity at pH 5.5 and $60^{\circ}C$. In addition, it had a pH stability range of 4.5-8.0 and a temperature stability range of $4-40^{\circ}C$. The enzyme was enhanced in the presence of $Co^{2+}$ and $Ca^{2+}$. Among various substrates tested, WSCT-50 (water-soluble chitin, degree of deacetylation 50%), glycol chitin, and crab chitosan (DD 71-88%) were deacetylated. Moreover, the CDA can handle N-acetylglucosamine oligomers $(GlcNAc)_{2-7}$.

• 생명과학회지
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• 제28권8호
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• pp.885-891
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• 2018

급성위막성대장염(Pseudomembranous colitis)은 C. difficile 세균이 분비하는 톡신A에 의해 유발되는 것으로 알려져 있다. 톡신A에 의한 점막 상피세포의 장벽기능 감소가 발병 원인으로 알려져 있다. 최근 연구에 의하면 톡신 A는 대장상피세포 속 HDAC-6의 활성을 높여 튜블린의 탈아세틸화를 증가시키는 것으로 알려져 있다. 튜블린 단백질의 탈아세틸화는 미세소관 불 형성을 초래하여 점막 상피세포의 극단적인 세포 형태 변형을 야기하게 되며 결국 상피세포의 고유기능인 장벽 기능이 파괴된다고 알려져 있다. 최근 연구자 등은 potassium acetate가 톡신A에 의한 튜블린 탈아세틸화와 미세소관 불 형성을 회복시켜 장염을 유의하게 억제함을 보고하였다. 따라서 본 연구에서는 아세틸기를 포함하는 또 다른 간단한 화학구조의 초산을 적용하여 톡신A의 세포독성을 억제하는지 확인해보고자 하였다. 인간 대장상피세포에서 초산 자극은 튜블린 단백질의 아세틸화를 유의하게 증가시켰다. 또한 초산은 대장상피세포 속 미세소관 형성과정도 강하게 촉진시킴을 확인하였다. 초산은 톡신A에 의한 튜블린 탈아세틸화와 미세소관 불 형성 그리고 세포독성 모두를 유의하게 회복시켰다. 이상의 결과는 초산에 의한 미세소관 형성 촉진이 톡신A에 의해 초래되는 세포골격계 파괴와 그로 인한 세포독성을 억제할 수 있음을 보여준다. 따라서 초산이 톡신A의 작용을 차단하여 위막성대장염 증상을 완화시킬 수 있는 치료제로서 개발 가치가 있음을 보여준다.

• Biomolecules & Therapeutics
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• 제19권3호
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• pp.282-287
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• 2011

Sirt1, a nicotinamide adenine dinucleotide ($NAD^+$)-dependent histone deacetylase, is known to deacetylate a number of proteins that are involved in various cellular pathways such as the stress response, apoptosis and cell growth. Modulation of the stress response by Sirtuin 1 (Sirt1) is achieved by the deacetylation of key proteins in a cellular pathway, and leads to a delay in the onset of cancer or aging. In particular, Sirt1 is known to play an important role in maintaining genomic stability, which may be strongly associated with a protective effect during tumorigenesis and during the onset of aging. In these studies, Sirt1 was generated in stably expressing cells and during the stimulation of DNA damage to examine whether it promotes survival. Sirt1 expressing cells facilitated the repair of DNA damage induced by either ionizing radiation (IR) or bleomycin (BLM) treatment. Fastened damaged DNA repair in Sirt1 expressing cells corresponded to prompt activation of Chk2 and ${\gamma}$-H2AX foci formation and promoted survival. Inhibition of Sirt1 enzymatic activity by a chemical inhibitor, nicotinamide (NIC), delayed DNA damage repair, indicating that promoted DNA damage repair by Sirt1 functions to induce survival when DNA damage occurs.

• Korean Journal of Chemical Engineering
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• 제35권12호
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• pp.2403-2412
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• 2018

The present study was aimed at evaluating the effect of variable sodium carbonate ($Na_2CO_3$) loading during wet air oxidation (WAO) pretreatment of rice straw in reducing biomass recalcitrance. The research study was intended to increase the cellulose recovery, hemicellulose solubilization, lignin removal in the solid fraction and limiting the generation of inhibitors in the liquid fraction while reducing the chemical input. The operating condition of $169^{\circ}C$, 4 bar, 18 min and 6.5 g/L $Na_2CO_3$ loading resulted in maximum cellulose recovery of 82.07% and hemicellulose solubilization and lignin removal of 85.43% and 65.42%, respectively, with a total phenolic content of 0.36 g/L in the liquid fraction. The crystallinity index increased from 47.69 to 51.25 along with enzymatic digestibility with an increase in $Na_2CO_3$ loading from 0 to 6.5 g/L as a result of removal of barriers for saccharification via effective cleavage of ether and ester bonds cross-linking the carbohydrates and lignin as indicated by FT-IR spectroscopy. A further increase in the $Na_2CO_3$ loading to 9.5 g/L did not significantly increase the sugar release. Thus, it was concluded that 6.5 g/L $Na_2CO_3$ during WAO is sufficient to increase the delignification and deacetylation, leading to significant changes in apparent cellulose crystallinity inter alia improvement in cellulose accessibility and digestibility of rice straw.

• 한국수산과학회지
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• 제32권2호
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• pp.121-126
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• 1999

Chitin deacetylase 추출을 위한 M. rouxii균의 성장 및 분해활성효소의 생산을 위한 공급원 중, 탄소원으로는 glucose 및 fructose 등이 가장 우수한 것으로 나타났고, 질소원으로는 yeast extract 및 pepton이 3:2의 비율로 총 $2\%$ 정도의 농도가 가장 효과적이었다. 성장 최적 pH는 4.5, 배양온도는 $25^{\circ}C$ 부근이었고 약산성 및 7.5이상의 영역에서는 균체의 성장 및 분해활성 효소의 활성이 급격히 저하되었으며 $35^{\circ}C$ 이상의 온도영역에서는 거의 생육하지 못하였다. 정제효소의 최적활성 pH 영역은 pH 5.5 부근이었으며 pH 4.0이하와 pH 8.0 이상의 반응조건에서는 급격한 활성저하를 초래하였고 반응 온도 $35^{\circ}C\~40^{\circ}C$ 영역에서 최고의 활성을 나타내었다. pH안정성에 있어서 pH 4.5 이하 및 pH 7.5 이상의 영역에서는 상당히 불안정한 것으로 나타났으며 $CaCl_2$ 및 $ZnC1_2$ 첨가에 의하여 약 $10\~20\%$의 활성이 증가되었으나 $Li^{2+}$ 및 $Hg^{2+}$ 등에 의해서는 현저한 활성저하현상을 나타내었다. 정제효소는 SH-화합물인 L-cysteine 과 S-S결합 절단제인 2-mercaptoethanol에 의해서는 활성이 증대되었고, SH 차단제인 $\sigma$-phenanthroline, CMB 및 금속 chelate제인 EDTA와 iodoacetate에 의해서는 활성이 현저히 저하되었다. 그리고, 정제효소의 $K_m$은 $1.2\%$였으며, $V_{max}$는 59.5U/mg 이었고, 20, 40, 60, 80mesh의 크기로 제조되어 진 분말 chitin에 대한 정제효소와의 반응에서 반응생성물인 acetic acid는 검출되지 않았다.