• 한국미생물·생명공학회지
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• 제22권3호
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• pp.252-258
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• 1994

Transglycosylation of stevioside in the attrition coupled heterogeneous reaction system using raw starch as a glycosyl donor has significant advantages over conventional reaction systems using liquefied starch as a donor. The transglycosylation of stevioside under the presence of organic solvent showed that transglycosylation reaction occurs via two steps ; initially from raw starch to cyclodextrin(CD), and then followed by transglycosylation of produced CD. Comparison of the transglycosylation efficiency of c$\alpha $-, $\beta $, $\gamma $-CDs indicated that $\alpha $-, $\beta $-CD are mainly utilized as a glycosyl donor for following reaction. The reaction mechanism of transglycosylation between stevioside and CD proceeded according to random sequential bireactant mechanism. The equilibrium constant of transglycosylation reaction of cyclodextrin glucanotransferase wase also evaluated. The structure of transglycosylated stevioside was confirmed by TLC, and it was found that glycosyl group(G$_{1}, $ ~ G$_{4}$-glycosidic bond.

• Bulletin of the Korean Chemical Society
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• 제26권5호
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• pp.815-818
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• 2005

• KSBB Journal
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• 제9권2호
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• pp.108-114
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• 1994

분쇄마찰매치 함유 불균일상 효소반응계에서 생전분을 당공여체로 한 stevioside의 당전이 반응의 kinetics에 관한 연구를 수행하였다. 생전분으로부터 CD를 생서하는 과정과 생성된 CD와 stevioside가 random sequenrial bireactant ,echanism으로 반응하여 당전이 equation을 유도하였다. 또한 유도된 반응식의 각종 kinetic constants을 평가하였다. 유도된 반응식을 Runge-Kutta integration법으로 계산하였으며, 계산 결과를 실험치와 비교하여 유도식의 효용성을 검토하였다. 유도된 kinetic equations는 당공여체인 생전분의 농도, stevioside의 농도, 그리고 중간산물인 CD의 농도 변화를 비교적 정획히 표시할 수 있었으며, 고효율 당전이 효소반응기 개발에 활용될 것이다.

• Bulletin of the Korean Chemical Society
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• 제25권1호
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• pp.139-142
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• 2004

• 한국미생물·생명공학회지
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• 제26권2호
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• pp.187-194
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• 1998

수계에서 전분 가수분해효소의 transglycosylation반응을 이용하여 배당체(glycoside)를 합성하였다. Glycosyl donor인 starch와 glycosyl acceptor인 benzylalcohol을 반응기질로 선택하였다. 시판되는 9종의 당가수분해효소의 transglycosylation활성을 조사한 결과 glucose와 한 종류의 glycoside만을 생산하는 amyloglucosidase(from Rhizopus sp.)를 반응효소로 선정하였다. Amyloglucosidase에 의해 합성된 배당체는 여러 가지 분석을 통해 glucose의 1번 OH기에 benzylalcohol이 ${alpha}$형태로 결합된 benzylalcohol-${alpha}$-glucoside(BG)임을 확인하였다. 수계에서 이 효소에 의한 transglycosylation 반응의 최적조건은 starch 50mg/$m\ell$, benzylalcohol 50 mg/ml, 온도 45$^{\circ}C$, 효소량 10 unit/ml, pH 5.0, 반응시간 32시간이었으며 합성된 BG는 amyloglucosidase에 의해서는 분해되지 않았고 ${alpha}$-glucosidase에 의해 glucose와 benzylalcohol로 가수분해되었다.

• Journal of Microbiology and Biotechnology
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• 제16권11호
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• pp.1678-1683
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• 2006

A novel suspension-phase enzyme reaction system for the intermolecular transglycosylation of L-ascorbic acid into 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid supplementing extrusion starch as the glycosyl donor was developed using cyclodextrin glucanotransferase from Thermoanaerobacter sp. A high conversion yield compared to the conventional soluble-phase enzyme reaction system using cyclodextrins and soluble starch was achieved. The optimal reaction conditions were 2,000 units of cycIodextrin glucanotransferase, 20 g/l of L-ascorbic acid, and 50 g/l of extrusion starch at $50^{\circ}C$ for 24 h. The new suspension-phase enzyme reaction system also exhibited several distinct advantages other than a high conversion yield, including a lower accumulation of oligosaccharides and easily separable residual extrusion starch by centrifugation or filtration in the reaction mixture, which will facilitate the purification of 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid. The new suspension-phase enzyme reaction system seems to be potentially applicable as the industrial process for the production of thermally and oxidatively stable 2-O-${\alpha}$-D-glucopyranosyl L-ascorbic acid.

• 미생물학회지
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• 제34권3호
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• pp.137-143
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• 1998

수계에서 전분 가수분해 효소의 transglycosylation 반응을 이용하여 배당체(glycoside)를 합성하였다. Glycosyl donor인 가용성전분과 glycosyl acceptor인 benzylalcohol을 기질로 하여 ${\alpha}$-amylase에 의해 합성되는 배당체는 glucose의 1번 OH기에 benzylalcohol이 ${\alpha}$형태로 결합한 benzylalcohol-${\alpha}$-glucoside(BG)와 benzylalcohol-${\alpha}$-maltoside(BM)이었다. pH 5.0의 반응에서는 주로 BG가, pH 8.0의 반응에서는 BM만이 합성되는 특이한 반응양상을 보였다. Transglycosylation 반응의 최적조건은 가용성전분 50 mg/ml, benzylalcohol 50 mg/ml, 온도 $30-35^{\circ}C$, 효소량 10 unit/ml이었으며, 합성된 BG는 ${\alpha}$-glucodisase에 의해 glucose와 benzylalcohol로 가수분해되었으며 BM의 경우는 pH 5.0에서는 glucose와 BG로 가수분해되었으나 pH 8.0이상에서는 전혀 분해되지 않았다. BM과 구조적으로 유사한 maltotriose는 pH 5.0에서 glucose와 maltose로 가수분해 되었으나 transglycosylation반응은 거의 일어나지 않았으며 pH 8.0에서는 가수분해도 transglycosylation반응도 일어나지 않았다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제5권3호
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• pp.174-180
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• 2000

Cyclodextrin glucanotransferase (CGTasa) from Thermoanaerobacter sp. was adsorbed on the ion exchange resin Amberlite IRA-900. The optimum conditions for the immobilization of the CGTase were pH6.0 and 600 U CGTase/g resin, and the maximum yield of immobilization was around 63% on the basis of amount ratio of the adsorbed enzyme to intial amount in the solution. Immobilixation of CGTase shifted the optimum temperature for the enzyme to peoduce transglycosylated xylitol from 7$0^{\circ}C$ to 9$0^{\circ}C$ and improved the thermal stability of immobilized CGTase, especially after the addition of soluble starch and calcium ions. Transglycosylated xylitol was continuoncly produced using immobilized CGTase in the column type packed bed reactor, and the operating conditions for maximum yield were 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) dextrin (13 of the dextrose equivalent) as the glycosyl donor, 10%(w/v) xylitor as the glycosyl acceptor, 20mL/h of medium fiow rate, and 6$0^{\circ}C$. The maximum yield of transglycosylated xylitol and productivity were 25% and 7.82 g.L-1.h-1, respectively. The half-life of the immobilized CGTase in a column type packed bed reactor was longer than 30 days.

• Bulletin of the Korean Chemical Society
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• 제16권7호
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• pp.625-630
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• 1995

α-Linked D-altropyranosidic derivatives were obtained by configurational change at C-3 of α-D-mannopyranosides as the key step in preparation of allyl and methyl α-D-glycopyranosides of 6-deoxy-D-altro-heptose. The manno-altro conversion was effected by sequential reactions of Swern oxidation and stereoselective borohydride reduction. Allyl 4,6-O-benzylidene-2-O-p-methoxybenzyl-α-D-mannopyranoside was transformed to the corresponding altropyranoside via 3-oxo-arabino-hexopyranoside. Allyl 7-O-benzyl-6-deoxy-3,4-O-isopropylidene-α-D-altro-heptopyranoside has been prepared as a glycosyl acceptor to be coupled with β-D-GlcpNAc-(1→3)-α-D-Galp glycosyl donor for the synthesis of an O-antigen repeating unit of Campylobacter jejuni serotypes O:23 and O:36. Stereoselective borohydride reduction also succeeded in yielding methyl 2,4,7-tri-O-benzyl-6-deoxy-α-D-altro-heptopyranoside from the corresponding 3-oxo-α-D-arabino-heptopyranoside. C-6 Homologation was achieved by sequential reactions of cyanide displacement of 6-sulphonates, reduction of the resulting heptopyranosidurononitrile with diisobutylaluminum hydride, hydrolysis of the imine, and further reduction with sodium borohydride.

• 미생물학회지
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• 제35권1호
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• pp.1-6
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• 1999

$\alpha$-Amylase 의 당전이반응에 의해 가용성전분으로부터 benzylalcohol-$\alpha$-glucoside(BG)를 합성하였다. 이 때 glycosyl 기의 공여체인 가용성전분 1%, glycosyl 기의 수용체인 benzylalcohol 90%, pH 5.0의 0.1M citrate 완충액 10%, Aspergillus oryzae 유래의 $\alpha$-amylase 10 unit를 함유하는 이상계(water-organic two phase )에서 당전이반응이 가장 효율적으로 일어났으며, $40^{\circ}C$, 80시간 정도의 반응에서 전문 10mg 으로부터 약 4mg 의 BG가 합성되었다. 합성초기에는 benzylalcohol-$\alpha$-maltoside(BM) 가 주로 생산되었다가 반응시간이 경과함에 따라 이는 가수분해되고 최종적으로는 BG 만이 생성되었다. 합성물질은 모두 환원력이 없고 $\alpha$-glucosidase 에 의해 가수분해되었드며 ESI-Mass 에 의해 분자량이 각각 270, 432로 측정되어 그 구조가 BG, BM 임을 확인하였다.