• KSBB Journal
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• v.16 no.2
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• pp.200-206
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• 2001

In this study we tried to optimize the enzyme reaction conditions for the synthesis of highly branched isomaltodextrin (Mw > 2.5 kDa) using two dextransucrases from L. mesenteroides B-742CB and B-512FMCM that are dextransucrase constitutive mutants. As the concentration of sucrose or the ratio of maltose to sucrose increased, the amount of dextran decreased and the number and the amount of acceptor-products (of sucrose or maltose) increased. With high sucrose concentration (over 34%), there was more branched isomaltodextrin (as acceptor products) than dextran. When the ratio of sucrose to maltose was 2.5, there produced 86.7% of isomaltodextrin were produced. The Mw of dextrans, however, was over 2${\times}$10(sup)6 and there was no significant amounts of branched clinical dextran or high molecular weight oligosaccharides. With the combined activities of B-742CB dextransucrase and B-512FMCM dextransucrase we could synthesize high molecular weight branched isomaltodextrin (Mw>2.5 kDa). The high molecular weight dextran was composed of high branches as B-742CB dextran.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.219-222
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• 1999

A simple sequence of membrane concentration and DEAE-Cellulose chromatography has been optimized to give a purified dextransucrase from Leuconostoc mesenteroides B-512FMCM with the highest specific activity (248.8 IU/mg protein) ever reported in high yield (overall 88.7%) for dextransucrase. When there was no sucrose in the dextransucrase and the dextran reaction digest, the dextransucrase hydrolyzed glucose from dextran. The glucose was transferred to the other glucoses from dextran and formed isomaltose and isomaltodextrin. The transglycosylation efficiency of glucose from dextran was much higher with acceptors. The dextransucrase can be used for the production of various kinds (or structures) of oligosaccharides using dextran and various acceptors with almost 100% theoretical yield.

• KSBB Journal
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• v.19 no.4
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• pp.269-273
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• 2004

A simple, fast and reproducible quantitative analysis method for sugar concentration composed in oligosaccharide mixture was developed. Two glass TLC plates were prepared per sample. After dipping one plate into the copper bicinchoninate reagent and the other plate into 5% sulfuric acid solution, both plates were baked in microwave oven until sugar spots were developed or the surface temperature of TLC plate becomes 60 to 70 $^{\circ}C$. The corrective factor values [F value =(the value of total sugar concentration converted as glucose unit/the value of reducing sugar concentration converted as glucose unit)/(polymerization degree of sugar)] of different molecular weight sugars were determined. Within the concentration of 0.25∼1.0 $\mu\textrm{g}$ in each sample loaded, the fructose-F (corrective factor value of fructose) was 0.45, yet for the higher concentration (2.5∼7.5 $\mu\textrm{g}$) fructose-F was 1.0. In case of glucose, in the range of 0.5∼7.5 $\mu\textrm{g}$, glucose-F was same as fructose-F, 1.0. However, as the molecular weight of sugar was increased, the F values were decreased in both maltodextrin and isomaltodextrin oligosaccharides in 0.5∼7.5 $\mu\textrm{g}$ of each sample loaded. Interestingly, F values were equal for the same molecular weight sugars, although the structures were different from each other. Using F value of each sugar, we could determine and compare the exact total sugar concentration of different molecular weight maltooligosaccharide and isomaltooligosaccharide. We also could determine if the unknown sugar was a reducing or non-reducing compound by using optimized TLC with microwave oven method.