• Microbiology and Biotechnology Letters
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• v.20 no.2
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• pp.156-163
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• 1992

Bacillus sp. was isolated from soil for its strong activity of cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19). The enzyme was purified by gel filtration and anion exchange column chromatography using FPLC. The purified enzyme exhibited its maximum CGTase activity in the pH range of 6~8 and the temperature range of 50~$70^{\circ}C$. The molecular weight was estimated as 114,000 by SDS-PAGE. The isoelectric point of the enzyme was 4.3. The CGTase of Bacillus sp. E l produced $\beta$-cyclodextrin mainly and did not produce a-cyclodextrin. The product ratio of $\beta$-cyclodextrin to $\gamma$-cyclodextrin was 7:l.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.370-378
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• 1989

An Alkalophilic Bacillus circulans that can produce significant amount of cyclodextrin glucanotransferase (CGTase) was newly isolated from soil. The culture filtrate was successively purified by ($NH_4$)$_2$$SO_4$precipitation, DEAE-Sephadex column chromatography, and Sephadex G-100 column chromatography. The enzymatic properties, including molecular weight, optimal pH and temperature, stability, and kinetic parameters, were determined. The cyclodextrin synthesis reaction catalized by the purified CGTase was also studied. The sweet potato and corn starch were found to be the most suitable substrates with 60% conversion to cyclodextrin. The highest conversion was achieved at the CGTase concentration of 900-1,100 units/g of soluble starch. The purified CGTase could also catalize the transglycosylation on stevioside.

• Journal of Microbiology and Biotechnology
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• v.11 no.2
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• pp.242-250
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• 2001

A Gram-positive bacterium (strain JB-13) that was isolated from soil as a producer of cyclodextrin glucanotransferase (CGTase) [EC 2.4.1.19] was identified as Panibacillus sp. JB-13. This CGTase could catalyze the transglucosylation reaction from soluble starch to L-ascorbic acid (AA). A main product formed by this enzyme with ${\alpha}-glucosidase$ was identified as $2-O-{\alpha}-D-glucopyranosyl{\;}_{L}-ascorbic$ acid (AA-2G) by the HPLC profile and the elemental analysis. CGTase was purified to homogeneity using ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Seohadex A-50, and gel chromatography on Sephacryl S-200HR. The molecular weight was determined to be 66,000 by both gel chromatography and SDS-PAGE. The isoelectric point of the purified enzyme was 5.3. The optimum pH and temperature was PH 7.0 and $45^{\circ}C$ respectively. The enzyme was stable in the range of pH 6-9 and at temperatures of $75{\circ}C$ or less in the presence of 15 mM ${CaCl_2}.\;{Hg^2+},\;{Mn^+2},{Ag^+},\;and\;{Cu^2+}$ all strongly inhibited the enzyme's activity.

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1627-1631
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• 2003

Molecular modeling was performed to comprehend the chiral recognition of ${\alpha}$-methoxy-${\alpha}$-trifluoromethylphenylacetic acid (MTPA) enantiomers by cyclomaltoheptaose (${\beta}$-cyclodextrin,${\beta}$-CD) and 6-amino-6-deoxy-cyclomaltoheptaose (am-${\beta}$-CD). Monte Carlo (MC) docking coupled to constant temperature molecular dynamics (MD) simulations was applied to the investigation for the ${\alpha}$-methoxy-${\alpha}$-trifluoromethylphenylacetic acid complexation with two different CDs in terms of the relative distribution of the interaction energies. The calculated results are finely correlated with the experimental observations in chiral recognition thermodynamics. Am-${\beta}$-CD as a host showed the superior enantio-discrimination ability to the native ${\beta}$-CD where the amino group of am-${\beta}$-CD was critically involved in enhancing the ability of chiral discrimination via the Coulombic interaction with MTPA.

• Biotechnology and Bioprocess Engineering:BBE
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• v.3 no.2
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• pp.78-81
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• 1998

Cyclodextrin glucanotransferase [CGTase, E.C.2.4.1.19] is an extracellular enzyme, which catalyzes he formation of ${\alpha}$-, ${\beta}$-, ${\gamma}$- CDs from starch. Their proportions of formations depend on enzyme sources and reaction conditions. To understand what determines the product specificity of CGTases, we examined the alteration of product specificity of CGTase from Bacillus macerans by organic solvent sand pH. At acidic pH range less than pH 6 where the enzyme was unstable, the ratio of ${\alpha}$-/ ${\beta}$-CD production was increased 4 times more than that at neutral pH range. As we increased the concentration of 2-butanol, ${\alpha}$-/ ${\beta}$-CD ratio was proportionally increased but / ratio remained constant. The ${\alpha}$-/ ${\beta}$-CD ratio of products was increased in the reaction media which yielded low products.

• Microbiology and Biotechnology Letters
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• v.22 no.3
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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.

• KSBB Journal
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• v.10 no.5
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• pp.491-498
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• 1995

In order to fraclionate ${\alpha}$-, ${\beta}$- and ${\gamma}$-cyclodextrins(CDs) from CD reaction mixture, various CD adsorbents were manufactured using fatty acids as the ligand molecules and anion exchange resins as matrix. Among several anion exchange resins, DEAE Cellulose was found to be the most suitable matrix for binding fatty acid. The binding stability between DEAE Cellulose and capric acid was tested under the various operation conditions, such as temperature, ethanol concentration, and ionic strength. Specific CD adsorbents manufactured with different chain-length fatty acids, saturated and unsaturated, were compared in terms of the recovery yield and selectivity of ${\alpha}$-, ${\beta}$- and ${\gamma}$-CDs. Stearic acid (C18, saturated) was identified as the most effective ligand for fractionation of ${\alpha}$-CD, and linoleic acid ((C18, unsaturated ) for ${\beta}$-CD. The spacer length between the matrix and ligand was required for effective adsorption of CDs, and the double bond in fatty acid molecules was also acted as an important factor determining recovery yield and selectivity. The elusion patterns of ${\alpha}$- and ${\alpha}$-, ${\beta}$-CD from column packed with stearic acid and linoleic acid CD adsorbents were also investigated at the various elusion conditions for fractionation of ${\alpha}$- and ${\beta}$-CD.

• Korean Journal of Food Science and Technology
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• v.16 no.4
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• pp.398-402
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• 1984

These experiments were conducted to investigate the substrate specificity, the hydrolysis products on the various carbohydrates and the hydrolysis rate on the various raw starches of the two purified glucoamylase produced by Rhizopus oryzae. Both of the glucoamylases hydrolyzed amylose, amylopectin, glycogen, soluble starch, pullulan, maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose and maltooctaose, but did not act on ${\alpha}-cyclodextrin$, ${\beta}-cyclodextrin$, raffinose, sucrose and lactose. When the reaction mixture of glucoamylase and polysaccharides were incubated $37^{\circ}C$for 32 hours, glucoamylase I hydrolyzed amylopectin, soluble starch and amyloses completely, but hydrolyzing glycogen up to only about 88%. Glucoamylase II hydrolyzed the previous four polysaccharides up to about 100%. Both of the glucoamylases produced only glucose for various substrates and did not have any ${\alpha}-glucosyl$ transferase activity. Both of the glucoamylases hydrolyzed raw glutinous rice starch almost complety, wheras they acted on raw potato starch, raw green banana starch, raw arrow root starch, raw corn starch, raw yam starch and raw high amylose corn starch weakly. Glucoamylase II hydrolyzed raw starches at the higher rate than glucoamylase I.

• Journal of Pharmaceutical Investigation
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• v.24 no.2
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• pp.85-94
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• 1994

Inclusion complexes of ketoconazole (KT) with ${\alpha}-$, ${\beta}-cyclodextrin$ (CD) and dimethyl-${\beta}-cyclodextrin$ $(DM{\beta}CD)$ in a molar ratio of 1:2 were prepared by freeze-drying and solvent evaporation methods. The interactions of KT with ${\alpha}-CD$, ${\beta}-CD$ and $DM{\beta}CD$ in aqueous solution and in solid state were investigated by solubility study, infrared (lR) spectroscopy and differential scanning calorimetry (DSC). The stability constant of $KT-DM{\beta}CD$ inclusion complex (lC) was found to be the largest among three inclusion complexes. Clear differences in IR spectra and DSC curves were observed between inclusion complexes and physical mixtures (PM) of KT-CDs. It was also shown by IR spectra and DSC curves that solvent evaporation method might be. superior to the freeze-drying method in preparing the inclusion complexes of KT-CDs. The dissolution rate of KT was markedly increased by inclusion complex formation with CDs in the buffer solution at pH 4.0 and pH 6.8. The mean dissolution time (MDT,min), which represents the rapidity of dissolution, was in the order of $KT-DM{\beta}CD$ IC (3.20) < $KT-{\beta}-CD$ IC (4.36) < $KT-{\alpha}-CD$ IC (6.99) < $KT-{\alpha}-CD$ PM (17.46)< $KT-{\beta}-CD$ PM (19.36) < $KT-{\beta}-CD$ PM (28.53). The dissolution rates of KT-CD ICsprepared by solvent evaporation method were faster than those of KT-CD ICs prepared by freeze-drying method.

• Preventive Nutrition and Food Science
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• v.7 no.3
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• pp.310-316
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• 2002

Extracellular cyclodextrin glucanotransferase (CGTase) from Paenibacillus sp. JK-12 was purified through sev-eral purification steps consisting of ammonium sulfate precipitation and chromatographies on DEAE-sephadex A-50 and Mono QIM HR5/5. The purified CGTase exhibited a single band on SDS-PAGE and was estimated to be approximately 82 kDa. The isoelectric point of the enzyme was 7.2 as determined by isoelectric focusing. The CGTase from Paenibacillus sp. JK-12 had a transglucosylation activity at the C-2 position of L-ascorbic acid. The optimum pH and temperature for the CGTase activity were 8.0 and 5$0^{\circ}C$, respectively. The enzyme activity was stable from pH 6.0 to 9.() and at temperatures up to 55$^{\circ}C$ at pB 8.0, having 80% residual activity. The activity of the CGTase was strongly resistant to metals such as A $g^{+}$ and $Ba^{2+}$ but slightly inhibited by H $g^{+}$, N $i^{2+}$ and $Mg^{2+}$. The enzymeproduced $\alpha$ -cyclodextrin ($\alpha$-CD) and $\beta$-CD as the main products from starch, but not ${\gamma}$-CD.X>-CD.