• Korean Journal of Microbiology
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• v.46 no.1
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• pp.80-85
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• 2010

Two different ${\alpha}$-amylase isozymes (AMY1 and AMY2) found in barley malt share up to 80% of amino acid sequence identity with each other, but their enzymatic properties differ remarkably. AMY1 shows the highest activity at low concentration of calcium ion, while AMY2 is highly active at high calcium concentration. Meanwhile, BASI (Barley ${\alpha}$-Amylase/Subtilisin Inhibitor) protein specifically inhibits only AMY2. In the present study, three separate regions in AMY genes (I, II, and III) were assigned on the basis of restriction enzyme sites and four kinds of chimeric amylases have been obtained by swapping a part of regions with each other. Each chimera gene was successfully over-expressed in Pichia pastoris. From the results of enzymatic characterization, both AMY211 and AMY122 showed the mixed or intermediate type of calcium-dependent activity between AMY1 and 2. Meanwhile, only AMY221 chimera could be significantly inhibited by BASI protein. As a result, it can be proposed that some amino acid residues in the region I and II, except region III, of barley ${\alpha}$-amylases play very important roles in calcium-dependency and interaction with BASI.

• Microbiology and Biotechnology Letters
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• v.38 no.2
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• pp.151-157
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• 2010

Barley malt produces two different $\alpha$-amylase isozymes (AMY1 and AMY2), which share up to 80% of amino acid sequence identity with each other. However, their enzymatic properties differ remarkably. In this study, five chimeric enzymes between AMY1 and 2 were constructed by staggered extension process (StEP) technique, and their enzymatic properties were characterized. According to the results, chimeric AMY-D2, D8, and E12 showed the mixed or intermediate types of calcium-dependent activity between AMY1 and 2. Meanwhile, only AMY-E10 chimera could be significantly inhibited by barley $\alpha$-amylase/subtilisin inhibitor (BASI) protein. Chimera AMY-C6 showed the same calcium-dependency as AMY1, while AMY-E10 was closely similar to AMY2. As a result, it can be proposed that some amino acid residues in the region II, III, and IV of barley $\alpha$-amylases can play very important roles in the interaction with BASI, and those in III, V, VI, and VII may partly affect on the calcium-dependent activity.

• Culinary science and hospitality research
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• v.19 no.5
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• pp.136-145
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• 2013

Currently many studies aimed at enhancing efficacy of medicinal food on biological activity using bioconversion technology including fermentation process. In this study, the quality characteristics and antioxidative activity of fermented Crataegi fructus was investigated. The antioxidant activity of fermented Crataegi Fructus was assessed by various radical scavenging assays using DPPH (2,2-Diphenyl-1-picrylhydrazyl), FRAP (Ferric ion reducing antioxidant power), Reducing power and ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)). Moisture content of fermented Crataegi Fructus was $39.3{\pm}0.06%$. Contents of crude ash, crude protein, and crude fat were $0.20{\pm}0.01$, $1.77{\pm}0.04$, and $1.40{\pm}0.59%$, respectively. Moreover, the hunter's color values of fermented Crataegi Fructus were 79.24 (lightnees), 1.58 (redness), and 31.25 (yellowness), respectively. Total phenolic contents of fermented Crataegi Fructus were $3,015{\pm}250$ GAE ${\mu}g/g$. The antioxidative activities of fermented Crataegi Fructus significantly increased in a dose dependent manner. In addition, fermented Crataegi Fructus slightly (10.4%) inhibited ${\alpha}$-glucosidase activity; however, there was no inhibitory activity against ${\alpha}$-amylase. In terms of proteolytic activity, fermented Crataegi Fructus showed a strong activity than pancreatin (used as a positive control). These results indicate that fermented Crataegi Fructus can be used as a natural resource for material aiding digestion.

• Preventive Nutrition and Food Science
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• v.20 no.2
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• pp.88-93
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• 2015

The purpose of this research was to investigate the inhibitory effect of jicama extract on ${\alpha}$-glucosidase activity, ${\alpha}$-amylase activity, and postprandial hyperglycemia in streptozotocin (STZ)-induced diabetic mice. Jicama extract showed prominent inhibitory effects against ${\alpha}$-glucosidase and ${\alpha}$-amylase. The $IC_{50}$ values of jicama extract against ${\alpha}$-glucosidase and ${\alpha}$-amylase were $0.083{\pm}0.004$ and $0.091{\pm}0.017mg/mL$, respectively. The increase in postprandial blood glucose levels was more significantly suppressed in the jicama extract-administered group than in the control group of both STZ-induced diabetic and normal mice. Blood glucose levels of the control group increased to $383.75{\pm}11.54$ and $402.50{\pm}15.32mg/dL$ at 30 and 60 min after a meal and decreased to $349.67{\pm}11.62mg/dL$ at 120 min. However, postprandial blood glucose levels were significantly decreased, when diabetic mice were fed with jicama extract ($342.00{\pm}15.73$, $367.00{\pm}13.00$, and $329.67{\pm}12.43mg/dL$ at 30, 60, and 120 min, respectively). Furthermore, the area under the curve was significantly decreased with jicama extract administration in diabetic mice (P<0.05). Therefore, these results indicate that jicama extract may help decrease postprandial blood glucose level by inhibiting ${\alpha}$-glucosidase.

• The Korean Journal of Food And Nutrition
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• v.7 no.4
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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 the Korean Society of Food Science and Nutrition
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• v.11 no.2
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• pp.1-6
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• 1982

The constituents of sugar, enzyme activity and number of pollens in standard honey (gathered from my own honey comb.) and commercial ones collected from local markets) were determined to know the difference between above two kinds of honey. The results obtained were as follows. 1. The constitution of saccharides in commercial honey was higher at 1% than the standard one. The average content showed 45% of fructose,41% of glucose, 3% of dextrin and 2% of sucrose. 2. Pollen contained in honey were mainly composed of oval and globe shape. The nunlber of pollen contained in standard honey was five times more than that in commercial ones .3. ${\alpha}-amylase$, ${\beta}-amylase$ and protease activity of standard honey were greated 5,2,2 times respectively comparing with that of commercial one, and acid protease activity with each sample was higher than the neutral.

• Applied Biological Chemistry
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• v.35 no.4
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• pp.232-236
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• 1992

In order to manufacture of soy paste, Changes of chemical composition and enzyme activity of soybean by different processing method were investigated. The results are summarized as follows: Changes of chemical compositions were; Raw(A) and soaked(B) soybeans contain about 2% of more crude fat than roasted(C) and steamed(D) soybeans, roasted and steamed soybeans contain $1.16{\sim}1.74%$ of more protein than those of raw and soaked soybeans, and Raw and roasted soybeans contain $0.11{\sim}0.41%$ of more crude fiber than those of soaked and steamed soybeans. ${\alpha}-amylase$, ${\beta}-amylase$, protease, lipase activity of raw and soaked soybeans were $2{\sim}5$ folds higher than those of roasted and steamed soybeans. Trypsin inhibitor activity of raw, soaked, roasted and steamed soybeans was indicated 56.7%, 42.9%, 32.9% and 20.8% in the order, respectively.

• Food Science and Preservation
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• v.16 no.6
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• pp.1008-1012
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• 2009

We investigated the biological activities of ethanol extracts obtained from five endive cultivars. Free radical-scavenging activities of extracts from Redoria, Halifax, Vintor, Kibora, and Metafora cultivars were 94.2%, 60.8%, 66.6%, 70.0% and 67.4%, respectively. The extract from Redoria showed the highest activity among all the tested samples including BHT (Butylated hydroxyanisole) and vitamine C, known as antioxidant. Endive extracts slightly (17.5 - 38.6%) inhibited $\alpha$-glucosidase activity. However, there is no inhibitory activity against $\alpha$-amylase. In terms of proteolytic activity, all endive extracts showed strong activity than pancreatin (used as a positive control), and the extract of Redoria also exhibited stronger activity than other extracts as well as free radical scavenging activity. These results indicate that endive, especially the Redoria cultivar, can be used as a natural resource for development of antioxidants or materials aiding digestion.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.519-526
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• 2003

Pancreatic lipase and ${\alpha}$-amylase inhibitory activities in purified extracts of pumpkin and job's tear were studied. Pancreatic lipase inhibitory activity was determined by measuring the rate of releasing oleic acid from triolein, and ${\alpha}$-amylase inhibitory activity was determined by iodometric method. The extracts of pumpkin and job's tear were purified using silica gel and C-18 gel column chromatographies. Treatment of pumpkin extract $(120\;{\mu}g/mL)$ in 3T3-L1 preadipocyte decreased differentiation about 95% and blocked accumulation of lipid. Body weights of rats fed high-fat diet containing dietary supplement decreased about 13% as compared with those fed only highfat diet. These results revealed dietary supplement is a good obesity-reducing material for decreasing lipid and carbohydrate absorptions.

• Korean Journal of Food Science and Technology
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• v.28 no.1
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• pp.34-39
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• 1996

We examined the effects of crude hemicellulose, alcohol-insoluble hemicellulose, high molecular weight soluble polysaccharide (HMS-P : MW>10 kDa) and low molecular weight souble polysaccharide (LMS-P : MW<10 kDa) fraction isolated from buckwheat (raw, roast and steam) on digestive enzyme activity in vitro. The enzyme activities were measured after the polysaccharides-enzyme mixtures were incubated at $37^{\circ}C$ for 5 min. Crude hemicellulose, alcohol-insoluble hemicellulose and residue lowered ${\alpha}-amylase$ activity, whereas HMS-P and LMS-P had no inhibitory effect. All polysaccharides except LMS-P lowered lipase activity. Crude hemicellulose, alcohol-insoluble hemicellulose, residue and HMS-P showed a marked decrease of trypsin and chymotrypsin activity but LMS-P showed a slight decrease of them.