• Applied Biological Chemistry
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• 제13권3호
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• pp.181-186
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• 1970

1) 세균액화효소(BLA), 세균당화효소 (BSA), isoamylase에 의한 전분의 가수분해 조건을 조사한 다음 이들 효소를 여러가지로 배합하여 물엿을 만들었다. 네가지 물엿 중에서 BLA와 BSA 또는 isoamylase를 같이 사용하여 만든 것은 밀감류 통조림용 시럽으로서 설탕시럽과 비슷한 결과를 나타 내었다. 2) BLA 및 BSA에 의한 전분분해액 중에서 두가지 소당류를 분리하고 그들의 구조를 결정한 바 ${\alpha}-1,6$결합을 하나씩 가지는 5당류 및 6당류임을 확인하였다.

• Journal of Microbiology and Biotechnology
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• 제20권12호
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• pp.1696-1701
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• 2010

The ${\alpha}$-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis ${\alpha}$-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.

• 한국식품영양학회지
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• 제10권2호
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• pp.180-185
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• 1997

찹쌀 20%, 엿기름 4%를 가하여 7시간 동안 당화시켜 제조한 식혜는 말통스 10.1%, 한계덱스트린 7.3%, 말토트링스 1.3%, 글루코오스 0.18%, 밥알 1.75%를 나타냈다. 알코올 침전, Biogel P-2의 겔 크로마토그래피로 식혜의 한계덱스트린을 정제하여 1H-NMR 분석한 결과 한계덱스트린은 $\alpha$-1,4-글루코시드 결합과 $\alpha$-1,6-글루코시드 결합이 5:1로 이루어졌고, pullulanase 처리한 결과 말토오스와 말토헥사오스까지의 분포를 나타내어 멥쌀식혜에서 얻은 한계덱스트린가 구조가 같은 결과이다. 밥알의 당함량은 26.4%, 단백질 함량은 41.6%를 나타냈다. 참쌀식혜의 한계덱스트린과 밥알에 30unit/ml의 $\alpha$-아밀라아제, 글\ulcorner아밀라아제, $\alpha$-글루코시다아제, $\beta$-아밀라아제를 작용시킨 결과 글루코아밀라아제 외에는 일부밖에 가수분해하지 at하였다. 인체의 효소인 $\alpha$-아밀라아제와 $\alpha$-글루코시다아제를 함께 작용시킨 결과 한계덱스트린의 가수분해율은 18%, 밥알의 가수분해율은 26%를 나타냈다.

• 미생물학회지
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• 제26권2호
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• pp.73-81
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• 1988

$\alpha$-Amylase (EC.3.2.1.1) of Neurospora crassa (ATCC9279) was cloned in E. coli HB101 using shotgun method, and the enzymes isolated from both N. crassa and E. coli were compared. Chromosomal DNA isolated from the spores of N. crassa was partially digested with PstI restriction endonuclease and rejoined to pBR322 which had been digested with the same enzyme. The resulting recombinant DNA were introduced into E. coli HB101 which had competancy by treating with $CaCl_{2}$. As the result, about 8000 colonies which showed tetracycline resistance were selected and two of the colonies which had 13.5Kb recombinant plasmid exhibit starch degrading activity on starch-containing plate when treated with D-cycloserine. $\alpha$-Amylases from both N.crassa and E. coli were isolated by using ammonium sulfate precipitation, DEAE-cellulose ion exchange column chromatography and Bio-Gel P150 gel foltration column. As the result, about 81.3 fold and 5.6 fold purifications in specific activities were obtained respectively, and specific activities of the gel filtrates were 6.1u/mg and 85u/mg respectively. The properties of both enzymes were compared and they showed quite the similar patterns in optimal temperature, optimal pH and had same molecular weight about 100,000 daltons on gel filtration method. Optimal temperatures for both enzymes were $70^{\circ}C$ and optimal pH were about 6 and 10.

• Journal of Microbiology and Biotechnology
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• 제23권8호
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• pp.1060-1069
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• 2013

Genome organization near cyclomaltodextrinases (CDases) was analyzed and compared for four different hyperthermophilic archaea: Thermococcus, Pyrococcus, Staphylothermus, and Thermofilum. A gene (CL1_0884) encoding a putative CDase from Thermococcus sp. CL1 (tccd) was cloned and expressed in Escherichia coli. TcCD was confirmed to be highly thermostable, with optimal activity at $85^{\circ}C$. The melting temperature of TcCD was determined to be $93^{\circ}C$ by both differential scanning calorimetry and differential scanning fluorimetry. A size-exclusion chromatography experiment showed that TcCD exists as a monomer. TcCD preferentially hydrolyzed ${\alpha}$-cyclodextrin (${\alpha}$-CD), and at the initial stage catalyzed a ring-opening reaction by cleaving one ${\alpha}$-1,4-glycosidic linkage of the CD ring to produce the corresponding single maltooligosaccharide. Furthermore, TcCD could hydrolyze branched CDs (G1-${\alpha}$-CD, G1-${\beta}$-CD, and G2-${\beta}$-CD) to yield significant amounts (45%, 40%, and 46%) of isomaltooligosaccharides (panose and $6^2$-${\alpha}$-maltosylmaltose) in addition to glucose and maltose. This enzyme is one of the most thermostable maltogenic amylases reported, and might be of potential value in the production of isomaltooligosaccharides in the food industry.

• 한국미생물·생명공학회지
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• 제24권6호
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• pp.726-732
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• 1996

To improve the fermentation characteristics(such as starch-degradability, ethanol tolerance, sugar and high-temperature tolerance) of recombinant haploid yeast Saccharomyces diastaticus K114, hybridization technique was used. The hybridization partner was S. diastaticus 1177 which had good glucoamylase activity and fermentabi- lity. The best hybrid HH64 showed improved ethanol tolerance, sugar and high-temperature tolerance. Especia- lly, the starch-fermentability was significantly improved, since the hybrid produced 1.60% (w/v) ethanol from 4% (w/v) starch, while the recombinant haploid K114 produced 1.30% (w/v) ethanol. The optimum temperature and pH for the starch-fermentation by the hybrid HH64 was 30$\circ$C and 5, respectively. The hybrid yeast HH64 produced 7.5% (w/v) ethanol directly from 20% (w/v) starch.

• 한국작물학회지
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• 제43권1호
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• pp.19-22
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• 1998

Effects of acute anoxia on carbohydrate hydrolytic enzyme activities and free amino acid contents in malt were examined. Malts were prepared with barley grains germinated for 7 days which contained the highest levels of amylolytic and(1-3,1-4)-$\beta$-glucanase activities. $\alpha$-Amylase and $\beta$-amylase activities in malts were not significantly affected by anoxia for 5 or 10 h.(1-3,1-4)-$\beta$-Glucanase activity, however, decreased about 7 to 10% by anoxia for 5 or 10 h. Alanine and $\gamma$-aminobutyric acid content changed drastically. Alanine contents in malts increased by 2.2- and 2-fold, and $\gamma$-aminobutyric acid contents by 1.4- and 1.9-fold under anoxia for 5 and 10 h, respectively.

• 한국생물물리학회:학술대회논문집
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• 한국생물물리학회 1999년도 학술발표회 진행표 및 논문초록
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• pp.35-35
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• 1999

Amylases catalyze the hydrolysis of starch material and play central roles in carbohydrate metabolism. The structure and a size exclusion column chromatography proved that the enzyme is a dimer in solution. The N -terminal segment of the enzyme folds into a distinct domain and comprises the enzyme active site together with the central (${\alpha}$/ ${\beta}$)$\sub$8/ barrel of the adjacent subunit.(omitted)

• 한국식품영양학회지
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• 제7권4호
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• pp.259-266
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• 1994

The hyperthermophilic archaebacterium Thermococcus profundus Isolated from a deep-sea hydrothermal vent system, produced several amylolytic enzymes such as extracellular amylase and pullulanase, intracellular a-1,4-91ucosidase in respone to the presence of complex carbohydrates In the growth medium. This strain showed high activities on 0.5% maltose than on complex carbohydrates One of the amylases was partially purified by ammonium sulfate precipitation, DEAE-Toyopearl chromatography. The amylase exhibited maximal activity at pH 5.5 and 80$^{\circ}C$, and was stable in the range of pH 5.5 to 9.5 and up to 80$^{\circ}C$ for 30 min. The enzyme activity was no dependence on Ca2+ and not inhibited by detergents. The amylase hydrolyzed soluble starch, amylose, amylopectin and glycogen to produce maltose and maltotriose with trace amounts of glucose, but not pullulan and ${\alpha}$-, ${\beta}$-, ${\gamma}$-cyclodextrin. Malto-oligosaccharides ranging from maltotetraose to maltoheptaose were hydrolyzed in an endo fashion.

• Journal of Microbiology and Biotechnology
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• 제18권4호
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• pp.730-734
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• 2008

Barley ${\alpha}$-amylase genes, amy1 and amy2, were separately cloned into the expression vector of $pPICZ{\alpha}A$ and recombinant Pichia strains were established by homologous recombination. Both AMYs from Pichia shared almost identical hydrolysis patterns on short maltooligosaccharides to result in glucose, maltose, or maltotriose. Against insoluble blue starch, AMY1 showed the highest activity at 0.1-5 mM calcium concentration, whereas 15-20 mM was optimal for AMY2. On the hydrolysis of soluble starch, unexpectedly, there was no significant difference between AMYs with increase of calcium. However, the relative activity on various starch substrates was significantly different between AMYs, which supports that the isozymes are clearly distinguished from each other on the basis of their unique preferences for substrates.