• KSBB Journal
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• 제16권2호
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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.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.86-89
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• 1999

The liquid of ripened Kimchi was spread on phenylethylalcohol sucrose medium and incubated at 20$^{\circ}C$ for 2 days in order to isolate Leuconostoc sp. strains. Twenty isolated colonies were identified as Leuconostoc sp. strains from sugar fermentation test. Dextransucrase activities of the isolated strains were determined and the strain J-2 showed highest activity. The morphological, cultural and physiological studies on these 5 strains showed that gram(+), spores(-), motility(-) and produced gas from glucose, acid in Whittenbury C. Only Y-1 strain produced ammonia from arginine.

• 한국미생물·생명공학회지
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• 제26권3호
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• pp.264-268
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• 1998

덱스트란수크라제는 Sucrose를 이용하여 덱스트란의 합성을 촉진하는데 sucrose이외에 다른 탄수화물이 효소 반응기 중에 존재하는 경우에는 Sucrose의 glucose를 이 탄수화물에 전달하는 반응을 촉진하여 새로운 구조의 산물을 생산한다. Leuconostoc mesenteroides B-742CB로 부터 얻은 덱스트란수크라제를 이용하여 플루란을 변형하고 그 조건을 최적화 하고자 했다. 수용성 변형 플루란은 이론적 수율의 57%(<$\pm$5)를 얻었다. 플루란 변형의 최적 조건으로는 pH 5.2, 28$^{\circ}C$ 에서 기질 0.37%(w/v)와 반응한 효소의 농도와 Sucrose농도가 각각 0.1 U/$m\ell$과 48mM일 때였다. 변형 플루란을 pullulanase, endodextranase로 처리하여 변형 전의 플루란과가수분해 상태를 비교 분석한 결과 변형전의 산물에 비해 이들 가수 분해 효소에 대해 더 저항성을 보였다. 변형 플루란을 methylation과 산가수분해 후 TLC한 결과 sucrose의 glucose가 플루란 glucose의 C3, C4, C6 위치의 free-OH group에 수식된 새로운 구조의 변형 플루란임을 확인하였다.

• KSBB Journal
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• 제16권2호
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• pp.188-199
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• 2001

10%의 $\alpha-(1\rightarrow3)$가지 결합을 갖고 $\alpha-(1\rightarrow6)$으로 연결된 댁스트란을 합성하는 텍스트란수크라제를 coding하는 유전자 (dsCB)를 Leuconostoc mesenteroides B-742CB로부터 분리하여 염기서열과 아미노산 서열을 결정하였다. dsCB가 포항된 6 6.lkb띄 DNA fragment는 4,536 bp의 염기로 구성된 하나의 open reading 잔ame(ORF)를 가지고 있었다. 추정된 아미노산 서열은 ORF의 698벤째 nucleotide 위치에 있는 start codon (ATG)으로부터 5,223번째 위치에 있는 slop codon(TAA)까지 였다. 구조 유전자의 아마노산은 1,5087H로 구성되고 분자량의 계산값은 168.6 kDa었고 non-denatured SDS-PAGE를 이용하여 활성 band툴 분석한 결과 170 kDa이었다. pDSCB를 까지고 있는 재조합 E. coli는 2 % sucrose배치에서 세포외로 댁스트란수크라제를 생산하였으며, soluble과 insoluble 텍스트 란을 생산하였다. 텍스트란수크라체의 효소 촉매작용에 관여 하는 것으로 얄려져있는 conserved region의 아미노산 중 Asp-492를 Asparagine으로 바꾸고자 point mutation을 시도하였고, 결과로 얻어친 D492N은 돌연변이 이전의 균에 비하여 활성이 1.6배 감소함을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제19권12호
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• pp.1644-1649
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• 2009

This study investigates the buffering effects of calcium salts in kimchi on the total acidity, microbial population, and dextransucrase activity. Calcium chloride or calcium carbonate was added to dongchimi-kimchi, a watery radish kimchi, and the effects on various biochemical attributes were analyzed. The addition of 0.1% calcium chloride produced a milder decrease in the pH after 24 days of incubation, which allowed the lactic acid bacteria to survive longer than in the control. In particular, the heterofermentative Leuconostoc genus population was 10-fold higher than that in the control. When sucrose and maltose were also added along with the calcium salts, the dextransucrase activity in the kimchi was elevated and a higher concentration of isomaltooligosaccharides was synthesized when compared with the control. Calcium chloride was determined as a better activator compound of dextransucrase than calcium carbonate, probably because of its higher solubility. Therefore, the results of this study confirm the ability of the proposed approach to modulate the kimchi fermentation process and possibly enhance the quality of kimchi based on the addition of dietary calcium salts.

• Journal of Microbiology and Biotechnology
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• 제18권6호
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• pp.1050-1058
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• 2008

A gene encoding a dextransucrase (dsrBCB4) that synthesizes only ${\alpha}$-1,6-linked dextran was cloned from Leuconostoc mesenteroides B-1299CB4. The coding region consisted of an open reading frame (ORF) of 4,395 bp that coded a 1,465-amino-acids protein with a molecular mass of 163,581 Da. The expressed recombinant DSRBCB4 (rDSRBCB4) synthesized oligosaccharides in the presence of maltose or isomaltose as an acceptor, plus the products included ${\alpha}$-1,6-linked glucosyl residues in addition to the maltosyl or isomaltosyl residue. Alignments of the amino acid sequence of DSRBCB4 with glucansucrases from Streptococcus and Leuconostoc identified conserved amino acid residues in the catalytic core that are critical for enzyme activity. The mutants D530N, E568Q, and D641N displayed a 98- to 10,000-fold reduction of total enzyme activity.

• Journal of Microbiology and Biotechnology
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• 제1권3호
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• pp.176-181
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• 1991

Studies on the optimum conditions for dextran production and the properties of dextransucrase (DS) were performed with Leuconostoc mesenteroides from Sikhae and Leuconostoc mesenteroides NRRL B-512(F). Dextransucrases were partially purified by lyophilization of the culture supernatant and subsequent gel chromatography on Bio-Gel A-5(m). The storage stabilities of Sikhae DS and B-512(F) DS were decreaed by the addition of dextranase. The optimum conditions for the enzyme stability were pH 5 and below $30^{\circ}C$. The B-512(F) DS lost the activity at pH 4, while Sikhae DS had 30% of the activity at the same pH. The activity of DS was decreased by EDTA. confirming the metalloprotein character of the enzymes, and was restored by the addition of calcium ions. Concanavalin A completely removed the activity of DSs, confirming the glycoprotein character of the enzymes.

• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.704-708
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• 1999

In addition to catalyzing the synthesis of glucan from sucrose as a primary reaction, glucansucrase also catalyzes the transfer of glucose from sucrose to other carbohydrates that are present or are added to the reaction digest. Using dextransucrase and altemansucrase, prepared from Leuconostoc mesenteroides B-742CBM and B-1355C, respectively, we modified the bacterial cellulose in Acetobacter xylinum ATCC10821 culture, and then produced a characteristic cellulose that is soluble and has a new structure. There were also some partially modified insoluble cellulose and oligosaccharides in the modification culture. After methylation and following acid hydrolysis of both the soluble and insoluble glucans, there were ($1{\rightarrow}4$) as well as ($1{\rightarrow}6$) and ($1{\rightarrow}3$) glycosidic linkages in the soluble glucan.

• 한국식품영양과학회지
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• 제29권5호
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• pp.802-806
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• 2000

Cellobiose에 당전이 효소인 dextransucrase를 여러 가지 조건별로 반응시켜 올리고당의 생성경향을 알아보았다. Cellobiose에 대한 acceptor 반응의 최적조건은 cellobiose와 surcose의 비율은 3:1, 효소의 양은 2 U/mL, buffer의 이온강도는 25 mM, pH는 5, 반응온도는 $25^{\circ}C$로 나타났다. Cellobiose의 acceptor products는 종합도 6까지 생성되었으며, 구조는 2-O-isomaltodextrinyl cellobiose로 추정하였다.

• 한국미생물·생명공학회지
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• 제26권2호
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• pp.143-150
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• 1998

덱스트란수크라제는 sucrose를 이용하여 덱스트란의 합성을 촉진하는데 sucrose이외에 다른 탄수화물이 효소 반응기 중에 존재하는 경우에는 sucrose의 glucose기를 이 탄수화물에 전달하는 반응을 촉진하여 새로운 구조의 산물을 생산한다. Leuconostoc mesenteroides B-742CB로 부터 얻은 덱스트란수크라제를 이용하여 입자 전분과 호화 전분에 sucrose의 glucose를 수식함으로써 변형을 시도하였다. 사용한 전분의 종류(Small starch 또는 Potato starch)에 따라 그리고 전분의 상태(입자 혹은 호화된 상태)에 따라 이론적 수율의 46-72%(s.d.<${pm}$5)를 얻었다. 변형 전분을 ${alpha}$-amylase, isoamylase, pullulanase 그리고 endo-dextranase로 처리하여 변형 전의 전분과 가수분해 상태를 비교한 결과 변형전의 산물에 비해 이들 가수분해효소에 대해 저항성을 보였다. 변형에서 얻어진 산물들의 methylation결과 입자 전분을 이용한 변형 반응의 산물의 변형 정도가 더 컸으며, 변형입자를 SEM으로 관찰하면 불규칙한 크기의 작은 조각의 산물을 확인할 수 있었다. 변형 반응으로 sucrose의 glucose가 전분 glucose의 C3, C4, 그리고 C6 위치의 free-OH group에 수식된 새로운 구조의 변형 산물을 생산하였고 이는 iodine에 의한 염색 정도를 크게 감소시켰으며 용해성을 증가시켰다.