• KSBB Journal
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• 제19권5호
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• pp.363-367
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• 2004

Leuconostoc mesenteroides NRRL B-1149 produces various glucoseyltransferases for the synthesis of dextran, levan and glucose-1-phosphate using sucrose as a substrate. A sucrose phosphorylase (1149SPase) was purified from L. mesenteroides NRRL B-1149 culture by using hollow fiber filtration (30 kDa cut off), Toyopearl DEAE 650 M column chromatography and following two times of DEAE-Sepharose column chromatographies. The specific activity of the purified 1149SPase was 25.7 (U/mg) with $16\%$ yield. The 1149SPase showed a molecular size of 56 kDa on denatured $10\%$ SDS-PAGE. The N-terminal amino acid sequence of the enzyme was MEIQNKAM. The optimum pH and temperature of this enzyme were 6.2~6.5 and 37^{circ}C, respectively. It had an apparent K_{m} of 6.0 mM and K_{cat} of 1.62/s for sucrose. 1149SPase crystal was formed by hanging drop diffusion technique using 20 mM calcium chloride dihydrate, 100 mM sodium acetate trihydrate pH 4.6 and $30\%$ 2-methyl-2,4-pentanediol as vaporizing and reservation solution. The 1149SPase catalyzes transferring of glucose from isomaltose or sucrose to salicin and salicyl alcohol by disproportionation reaction or acceptor reaction and synthesized two acceptor products, respectively.

• 한국식품과학회지
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• 제23권1호
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• pp.93-97
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• 1991

호알칼리성 Bacillus sp. YC-335가 생산하는 CGTase의 효소학적 특성 및 작용반응을 살펴보았다. ${\alpha}-CD,\;{\beta}-CD$ 및 ${\gamma}-CD$로부터 glucosyl residues를 설탕으로 전이시키는 반응에 대한 효소의 최대 반응속도, Vmax 값은 각각 $16.13,\;21.8,\;9.8{\mu}moles glucose/min/mg\;protein$이었으며 Km 값은 각각 1.68, 0.33, 0.37 mM이었다. 효소의 전분 가수분해활성은 여러 당류에 의해 촉진되었으며 특히 전분 가수분해 산물인 maltose와 glucose에 의한 효과가 가장 좋았다. 이 효소는 ${\beta}CD$에 의해 효소의 전분 분해활성이 저해되었으며 비경쟁적 저해형식을 보였다. 또한 전분으로부터 효소작용에 의해 생성된 산물을 총당량법 및 HPLC 분석을 통해 조사한 결과 이 효소는 cyclization 작용 뿐만 아니라 transglycosylation 작용과 disproportionation 작용을 가지는 것으로 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1809-1813
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• 2006

A gene corresponding to 4-${\alpha}$-glucanotransferase (${\alpha}GTase$) was cloned from the thermophilic bacterium Thermus brockianus. The nucleotide sequence analysis showed that the ${\alpha}GTase$ gene is composed of 1,503 nucleotides and encodes a polypeptide that is 500 amino acids long with a calculated molecular mass of 57,221 Da. The deduced amino acid sequences of Thermus brockianus ${\alpha}GTase$ (TBGT) exhibited a high level of similarity to the amino acid sequence of ${\alpha}GTase$ of Thermus thermophilus (86%), but low level of homology to that of E. coli (26%). The TBGT gene was overexpressed in E. coli BL21, and the corresponding recombinant enzyme was efficiently purified by Ni-NTA affinity chromatography. The enzymatic characteristics revealed that optimal pH and temperature were pH 6 and $70^{\circ}C$, respectively. Most interestingly, TBGT reacted with small oligosaccharides, especially maltotriose, to form various maltooligosaccharides by using its disproportionation activity.

• 대한화학회지
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• 제21권3호
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• pp.204-209
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• 1977

경북 구룡포산 천연제올라이트에 대한 물리적 성질과 촉매활성이 검토되었다. 정량분석과 X-선 회절스펙트럼으로부터 천연제올라이트는 30 ${\sim}$ $40{\%}$의 mordenite를 함유하고 있다. 원시료의 표면적은 $75m^2$/g에 불과하나 2N 염산으로 처리시 $320m^2$/g에 이른다. 톨루엔불균화 반응에 대해서도 2N에서 최대의 전화율을 보여주나, 활성저하가 심한 것으로 나타났으며 크실렌에 대한 벤젠의 선택성은 처리한 산농도가 증가함에 따라 감소하는 것으로 나타났다.

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 2003년도 International Symposium of Silkworm/Insect Biotechnology and Annual Meeting of Korea Society of Sericultural Science
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• pp.66-70
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• 2003

The first line of antioxidant defense against reactive oxygen species includes the enzymatic activity of the superoxide dismutase (SOD) that catalyzes the disproportionation of superoxide to hydrogen peroxide and water. The SOD mainly removes highly toxic $O_2$$^{[-10]}$ and also prevents $O_2$$^{[-10]}$ mediated reduction of iron and subsequent OH$^{[-10]}$ generation. Along with an interest in SOD as a first line of defense against damage mediated by the superoxide anion, the SOD1 enzyme has been subjected to investigation in the molecular and cellular level. (omitted)

• Macromolecular Research
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• 제17권12호
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• pp.950-955
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• 2009

The physical and rheological properties of thermoplasticized irradiation-crosslinked polyethylene foam using supercritical methanol treatment were investigated by GPC, FTIR, DSC, WAXS, DMTA and UDS. The polyethylene foam was selectively decrosslinked into thermoplasticized polyethylene in an appropriate supercritical methanol condition without any undesirable side reactions such as oxidation and disproportionation. The thermoplasticization was promoted with increasing reaction temperature to reach completion above $380^{\circ}C$. The supercritical reaction condition affected the crystallization behavior, and mechanical and rheological properties of the decrosslinked polyethylene foam, but not its crystallographic structure or crystallinity.

• 대한화학회지
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• 제22권6호
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• pp.423-430
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• 1978

트리옥산을 니트로벤젠 용매중에서 Ti$Cl_4$로서 중합시킬때 개시 반응기구를 연구하였다. 중합반응속도를 측정한결과 미량의 물이나 메탄올을 첨가하면 반응속도가 급격히 감소하였으며 중합을 개시하는 데는 조촉매로서 다른 물질이 필요 없음이 알려졌다. 유전상수 측정결과에 의하면 중합과정중 양성이온이 생기지 않으며 중합제나 개시제 용액의 전기전도도를 측정한 결과 개시 반응은 니트로벤젠 용매중에서 개시제가 동종간 주고 받기반응에 의하여 생긴 Ti$Cl_3^+$ 양이온에 의하여 일어난다는 것이 판명되었다.

• 한국식품과학회지
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• 제48권6호
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• pp.542-547
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• 2016

The thermal properties of ramie leaf ${\beta}$-amylase (RBA) were examined to develop a novel process for enzyme purification. The thermostability of RBA extract prepared from ramie leaf powder was examined at various temperatures. RBA activity decreased slightly, whereas other carbohydrate-active enzymes, such as $\small{D}$-enzyme, were rapidly inactivated during 30 min incubation at $60^{\circ}C$. When the heat-treated extract was incubated with various substrates, maltose was produced exclusively as the major product, whereas the untreated crude extract produced maltose and other maltooligosaccharides. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, fewer protein bands were observed for the heat-treated extract than the untreated extract, indicating that the thermostable RBA was partially purified and other thermolabile enzymes were eliminated. Thus, the treatment of the RBA extract at $60^{\circ}C$ for 30 min resulted in 5.4-fold purification with a recovery yield of 90%.

• Journal of Microbiology and Biotechnology
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• 제8권3호
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• pp.251-257
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• 1998

Cycloinulooligosaccharide fructanotransferase (CFTase) which produces cyclofructan from inulin was purified 332-fold from a culture broth of Bacillus macerans CFCl. The molecular mass of the CFTase was estimated to be 110 kDa by SDS-polyacrylamide gel electrophoresis and gel filtration, indicating that the enzyme has a monomer structure. The maximal level of enzyme activity was observed at pH 7.5 and $45^{\circ}C$. The enzyme was stable in the pH range 6.0 to 9.5, and at temperatures up to $45^{\circ}C$ for 1 h. The enzyme activity was completely inhibited in the presence of 0.5 mM $Ag^+\;or\;Cu^2+$ ion. None of sucrose (GF), l-kestose (GF2), or nystose (GF3) were found to be substrates for the CFTase, but inulooligosaccharides larger than nystose were attacked by the enzyme. The CFTase catalyzes not only the cyclization as the major reaction, but also disproportionation and coupling reactions involving intermolecular transfructosylation in the same manner as cyclodextrin glucanotransferase (CGTase) (EC 2.4.1.19).

• 한국진공학회:학술대회논문집
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• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
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• pp.139-139
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• 2000

We have investigated the adsorption and reaction of Cu(hfac)(vtms) on Cu(111) surface using TPD. The recombinative desorption of Cu(hfac)(vtms) reversibly occurs between 240 and 340K. The remaining Cu(hfac) after the desorption of vtms preferentially undergo the desorption between 330 and 370K as intact Cu(hfac) than the disproportionation reaction. The disprportionation reaction between adsorbed Cu(hfac) was observed to occur between 420 and 520K with an activation energy of 34~37 kcal/mol. the geometries and adsorption sites of Cu(hfac) have been also calculated by means of extended H ckel method. It is found that standing Cu(hfac) is more stable than lying-down Cu(hfac) on the Cu(111) surface and the Cu(hfac) molecule prefers to adsorb on the hollow site over the top or bridge sites. We also have investigated the surface modification effect by preadsorbed I and Na atoms on the reaction Cu(hfac)(vtms).