• Mycobiology
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• v.29 no.4
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• pp.183-189
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• 2001

Extracellular amylase properties were examined with the mycelium of Tricholoma matsutake isolated from ectomycorrhizal roots of Pinus densiflora. The molecular weights of $\alpha$-amylase and glucoamylase were estimated as 34.2 kD and 11.5 kD, respectively, after eluted through Superdex 75 column. The optimum pH of the purified enzyme was found in a range of pH $5.0{\sim}6.0$, with a peak at pH 5.0. The activities of these enzymes were stable from $4^{\circ}C\;to\;30^{\circ}C$. The $\alpha$-amylase of T. matsutake readily hydrolyzed soluble starch and amylose-B, while it weakly hydrolyzed glycogen, dextrin, amylose and amylose-A. The main products of hydrolysis were confirmed to be glucose, maltose and maltotriose on the basis of the similarities in the thin layer chromatographic mobility.

• Journal of Applied Biological Chemistry
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• v.43 no.4
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• pp.240-245
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• 2000

Two genes encoding maltooligosyltrehalose synthase (SaMTS) and maltooligosyltrehalose trehalohydrolase (SaMTH) were isolated from a hyperthermophilic microorganism, Sulfolobus acidocaldarius (ATCC 49462). ORFs of the SaMTS and SaMTH genes are 2,163 and 1,671 bp long and encode 720 and 556 amino acid residues, respectively. A bifunctional fusion enzyme (SaMTSH) was constructed through the gene fusion of SaMTS and SaMTH. Recombinant SaMTS, SaMTH, and SaMTSH fusion enzyme were overexpressed in E. coli BL21. SaMTS and SaMTH produced trehalose and maltotriose from maltopentaose in a sequential reaction. SaMTSH fusion enzyme catalyzed the sequential reaction in which the formation of maltotriosyltrehalose was followed by hydrolysis leading to the synthesis of trehalose and maltotriose. The SaMTSH fusion enzyme showed the highest activity at pH 5.0-5.5 and $70-75^{\circ}C$. SaMTS, SaMTH, and SaMTSH fusion enzyme were active in soluble starch, which resulted in the production of trehalose.

• Archives of Pharmacal Research
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• v.8 no.2
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• pp.67-75
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• 1985

To find emylase inhibitors produced by microorganisms from soil, a strain which had a strong inhibitory activity against bacteria .alpha.-amylase was isolated from the soil smaple collected in Seoul. The morphological and physiological characteristics of this strain on several media and its utilization of carbon sources showed that it was one of Streptomyces specties according to the international Streptomyces Project method. The amylase inhibitor of this strain was purified by means of acetone precipitation, adsorption on Amberlite XAD-2, and column chromatography on Amberlite CG-50 and SP-Sephadex C-25. The inhibitor was stable at the pH range of 1-10 and at 100.deg.C for half an hour, and had inhibitory activities against other amylases such as salivary .alpha.-amylase, pancreatic .alpha.-amylase, fungal .alpha.-amylase and glucoamylase. The kinetic studies of the inhibitor showed that its inhibitory effect on starch hydrolysis by .alpha.-amylase was non-competitive.

• Proceedings of the Korean Biophysical Society Conference
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• 1999.06a
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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)

• Journal of Preventive Medicine and Public Health
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• v.7 no.1
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• pp.107-113
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• 1974

Many factors exert an influence on enzyme activity and thus on the rate of reactions that they catalyse. The most important of these factors are pH, temperature, substrate concentration, and the concentration of some inhibitors present. A solution of the enzyme diastase, which breaks down molecules of the polysaccharide starch to the disaccharide maltose by hydrolysis, was provided. Activity of this enzyme was measured by the rate at which starch was removed from the reaction mixture. These experiments were designed to study this reaction rate under varying conditions and the following results were obtained. 1. The range of optimum pH for this enzyme at room temperature was 4.0-7.0 and the optimum pH was 5.0. 2. The range of optimum temperatures for this enzyme at pH 7.0 was $30^{\circ}C-50^{\circ}C$ and the optimum temperature was $40^{\circ}C$. 3. The relationship between the enzyme activity and substrate concentration could be expressed by the Michaelis-Menten equation. The limiting velocity of this enzyme at room temperature and pH 7.0 was $415{\mu}g$ starch removed/ml of reaction mixture/min and $K_m$, Michaelis constant, was $343{\mu}g/ml$. 4. Inhibitors NaCl and $HgCl_2$ blocked this enzyme activity completely at 1% and 0.01% respectively.

• Microbiology and Biotechnology Letters
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• v.44 no.3
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• pp.363-369
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• 2016

A putative cyclomaltodextrinase gene (licd) was found from the genome of Listeria innocua ATCC 33090. The licd gene is located in the gene cluster involved in maltose/maltodextrin utilization, which consists of various genes encoding maltose phosphorylase and sugar ABC transporters. The structural gene encodes 591 amino acids with a predicted molecular mass of 68.6 kDa, which shares less than 58% of amino acid sequence identity with other known CDase family enzymes. The licd gene was cloned, and the dimeric enzyme with C-terminal six-histidines was successfully produced and purified from recombinant Escherichia coli. The enzyme showed the highest activity at pH 7.0 and 37℃. licd could hydrolyze β-cyclodextrin, starch, and maltotriose to mainly maltose, and it cleaved pullulan to panose. It could also catalyze the hydrolysis of acarbose to glucose and acarviosine-glucose. In particular, it showed significantly higher activity towards β-cyclodextrin and maltotriose than towards starch and acarbose. licd also showed transglycosylation activity, producing α-(1,6)- and/or α-(1,3)-linked transfer products from the acarbose donor and α-methyl glucopyranoside acceptor.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.208-215
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• 2017

A cyclomaltodextrinase (SPCD) gene was cloned from Streptococcus pyogenes ATCC 700294. Its open reading frame consists of 567 amino acids (66.8 kDa), which shows less than 37% of amino acid sequence identity with the other CDase-family enzymes. The homo-dimeric SPCD with C-terminal six-histidines was expressed and purified from Escherichia coli. It showed the highest activity at pH 7.5 and $45^{\circ}C$, respectively. SPCD has the broad substrate specificities against ${\beta}$-cyclodextrin, starch, and maltotriose to produce mainly maltose, whereas it hydrolyzes pullulan to panose. It can also catalyze the hydrolysis of acarbose to glucose and acarviosine-glucose. Interestingly, it showed much higher activity on ${\beta}$-cyclodextrin and acarbose than that on starch, pullulan, or maltotriose, which makes SPCD distinguished from common CDase-family enzymes. Although SPCD has significantly high acarbose-hydrolyzing activity, it showed negligible transglycosylation activity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.4
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• pp.593-598
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• 2011

This research was performed to determine the quality characteristics of steamed bread by the number of times through the fermentation process. The number of fermentations varied from 1 to 5 while the steamed bread was prepared by measuring the duration of fermentation, and samples were analyzed in terms of general ingredients, physical properties, in vitro starch hydrolysis, protein digestibility, and sensory characteristics. Five times of fermentation resulted in significantly higher water content (p<0.01), and single fermentation led to the highest protein content (p<0.01). Protein levels decreased as fermentation was repeated. Single fermentation gave the lowest specific bread volume (p<0.05) and it increased with the number of fermentation times. Physical properties also varied with the number of times of fermentation. With more fermentation, hardness, gumminess, and chewiness decreased (p<0.01), whereas resilience (p<0.01) and cohesiveness (p<0.05) increased. In vitro starch hydrolysis was higher with 5 times of fermentation than with single to 3 times of fermentation (p<0.05). Protein digestibility was also higher with 5 times of fermentation (p<0.05). In sensory evaluations, whiteness scores were higher with 4 to 5 times of fermentation (p<0.01) whereas scores for crumb uniformity were lower with 4 and 5 times of fermentation. Moistness (p<0.01), cohesiveness (p<0.01), and chewiness (p<0.05) showed their highest scores with 4 times of fermentation.

• The Korean Journal of Mycology
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• v.20 no.1
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• pp.65-71
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• 1992

The two isolates of Streptomyces antagonistic to Phytophthora nicotianae var. parasitica and Fusarium oxysporum f. sp. vasinfectum were identified as based on the morphological, cultural and physiological characteristics on various culture media. Spore chains of St-11 isolate was rectus-flexibilis(RF), whereas the other isolate, St-20, was shown rectinaculum-apertum(RA). Spore surface of St-11 isolate was smooth, while St-20 was spiny. Aerial mycelia of the two isolates were all gray color and growing conditions on media were good as a whole. Any soluble pigment was not shown in cultivation of the two isolates. Stoll isolate showed negative response on starch hydrolysis and gelation liquefaction, whereas St-20 isolate was positive on starch hydrolysis and a negative on gelatin reaction. Stoll isolate was identified as Streptomyces bikiniensis and St-20 Streptomyces echinoruber, respectively.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.1
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• pp.46-53
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• 2004

In this study, we compared the levels of methylotrophic bacterial community diversity in the leaf, stem, grain, root and rhizosphere soil sainples of four rice cultivars collected from three regions of Korea. Thirty five pigmented and five non-pigmented isolates showing characteristic growth on methanul were obtained. When phylotypes were defined by performing numerical analysis of 42 characteristics, four distinct clusters were formed. While two clusters, I and IV diverged on the basis of nitrate and nitrite reduction, other two clusters, comprising only pink pigmented colonies, diverged on the basis of cellulase activity. Out of the two reference strains used in the analysis, Methyhbacterium extorquens AM1 diverged from all the clusters and M. fujisawaense KACC 10744 grouped under cluster III. All the isolates were positive for urease, oxidase, catalase and pectinase activity and negative for indole production, MR and VP test, $H_2S$ production, starch, and casein hydrolysis. No clusters were found to possess thermotolerant isolates, as no growth of the isolates was observed at $45^{\circ}C$. Two strains in cluster I were found to possess gelatin hydrolysis and methane utilizing properties respectively. Most of the isolates in all the four clusters utilized monosaccliarides, disaccharide and polyols as carbon source. Six isolates showed considerable nitrogenase activity ranging from 86.2 to $809.9nmol\;C_2H_4\;h^{-1}\;mg^{-1}$ protein.