• Korean Journal of Food Science and Technology
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• v.48 no.4
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• pp.341-346
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• 2016

The AMY2B gene, encoding human pancreatic ${\alpha}$-amylase isozyme (HPA II), was expressed in Pichia pastoris, and the effects of chloride ions on HPA II activity toward starch substrates were investigated. As seen with chloride ion-dependent ${\alpha}$-amylases-including HPA I, the isozyme of HPA II-chloride ions increased enzyme activity and shifted the optimal pH to an alkaline pH. The activity enhancement by chloride was more significant at pH 8 than that at pH 6, suggesting that the protonation state of the general acid/base catalyst of HPA II was important for the hydrolysis of starches at an alkaline pH because of the increase in its $pK_a$ by chloride ions. The turnover values for cereal starches as the substrates markedly increased in the presence of chloride by up to 7.2-fold, whereas that for soluble starch increased by only 1.7-fold. Chloride inhibited substrate hydrolysis at high substrate concentrations, with $K_i$ values ranging from 6 to 15 mg/mL.

• BMB Reports
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• v.37 no.4
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• pp.429-438
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• 2004

Complementary DNAs encoding $\alpha$-amylases (Amyl I, Amyl III) and glucoamylase (GA I) were cloned from Aspergillus awamori KT-11 and their nucleotide sequences were determined. The sequence of Amyl III that was a raw starch digesting $\alpha$-amylase was found to consist of a 1,902 bp open reading frame encoding 634 amino acids. The signal peptide of the enzyme was composed of 21 amino acids. On the other hand, the sequence of Amyl I, which cannot act on raw starch, consisted of a 1,500 bp ORF encoding 499 amino acids. The signal peptide of the enzyme was composed of 21 amino acids. The sequence of GA I consisted of a 1,920 bp ORF that encoded 639 amino acids. The signal peptide was composed of 24 amino acids. The amino acid sequence of Amyl III from the N-terminus to the amino acid number 499 showed 63.3% homology with Amyl I. However, the amino acid sequence from the amino acid number 501 to C-terminus, including the raw-starch-affinity site and the TS region rich in threonine and serine, showed 66.9% homology with GA I.

• BMB Reports
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• v.37 no.4
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• pp.422-428
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• 2004

Raw-starch-digesting $\alpha$-amylase (Amyl III) was purified to an electrophoretically pure state from the extract of a koji culture of Aspergillus awamori KT-11 using wheat bran in the medium. The purified Amyl III digested not only soluble starch but also raw corn starch. The major products from the raw starch using Amyl III were maltotriose and maltose, although a small amount of glucose was produced. Amyl III acted on all raw starch granules that it has been tested on. However, it was considered that the action mode of the Amyl III on starch granules was different from that of glucoamylase judging from the observation of granules under a scanning electron microscope before and after enzyme reaction, and also from the reaction products. Glucoamylase (GA I) was also isolated and it was purified to an electrophoretically pure state from the extract. It was found that the electron micrographic features of the granules after treatment with the enzymes were quite different. A synergistic effect of Amyl III and GA I was observed for the digestion of raw starch granules.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.5
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• pp.655-661
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• 2010

The nutraceutical role of fermented omija (Schizandra chinensis) beverage (FOB) was determined through the analysis of fibrinolytic and alcohol metabolizing activities, nitrite scavenging activity, and angiotensin converting enzyme and $\alpha$-glucosidase inhibitory effects. Firstly, FOB increased fibrinolytic activity in a dose-dependent manner and indicated angiotensin converting enzyme inhibitory activity of 94.8% at 20% FOB (0.6 mg/mL). In addition, the inhibitory activities of FOB on $\alpha$-amylase and $\alpha$-glucosidase were determined to be 100% at 100% FOB (3 mg/mL) and 49% at 60% FOB (1.8 mg/mL), respectively. Nitrite scavenging activity of FOB was about 96.1%, 72.3%, and 68.3% on pH 1.2, 3.0, and 6.0 at 100% FOB, respectively. To determine influence of FOB on alcohol metabolism, the generating activities of reduced-nicotinamide adenine dinucleotide (NADH) by alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) were measured. Facilitating rate of ADH activity was 70.3% at 50% FOB, but ALDH activity was not affected. These results revealed that FOB has a strong alcohol metabolizing activity, and fibrinolytic and nitrite scavenging activities and exhibits the angiotensin converting enzyme, $\alpha$-amylase, and $\alpha$-glucosidase inhibitory activities.

• Journal of the Korean Society of Food Culture
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• v.36 no.5
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• pp.522-529
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• 2021

This study was conducted to analyze the antioxidant and antidiabetic activities of acorns according to the types of Quercus serrata Thunb (QST) and Q. acutissima Carruther (QAC). The total polyphenol contents of the extracts from QST and QAC were 220.59 and 320.96 mg GAE/g, respectively. The content of total polyphenol of QAC was higher than that of QAC (p<0.001). DPPH (2,2 Diphenyl 1 picrylhydrazyl) radical scavenging activity, reducing power and superoxide dismutase (SOD)-like activity were increased in a concentration-dependent manner by both acorn extracts, and QAC showed high activity in all antioxidant experiments (p<0.05). The inhibitory activities of α-glucosidase and α-amylase were also increased in a concentration-dependent manner, and QAC showed higher inhibitory activity than QST (p<0.05). Our study indicates that QST and QAC are functional food materials with high antioxidant and antidiabetic activities. In addition, QAC has a higher physiological activity than QST.

• Journal of Dairy Science and Biotechnology
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• v.38 no.4
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• pp.207-221
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• 2020

This study aimed to investigate the physiological characteristics and anti-obesity effects of milk fermented by L. plantarum KI134. The lipase, α-amylase, and α-glucosidase inhibitory activities of milk fermented by L. plantarum KI134 was 94.57±1.25%, 9.44±2.85%, and 2.74±1.24% (10 fold dilution), respectively. L. plantarum KI134 showed higher sensitivity to clindamycin and erythromycin in comparison to sixteen different antibiotics. It demonstrated the highest resistance toward ampicillin and vancomycin. The strain showed higher β-galactosidase, leucine arylamidase, valine arylamidase, acid phosphatase, β-glucosidase, and N-acetyl-β-glucosaminidase activities compared to other enzymes. It also did not produce carcinogenic enzymes, such as β-glucuronidase. The survival rate of L. plantarum KI134 in 0.3% bile was 96.90%. Moreover, the strain showed a 91.45% survival rate at a pH of 2.0. L. plantarum KI134 has resistance to Escherichia coli, Salmonella Typhimurium, Listeria monocytogenes, and Staphylococcus aureus at the rates of 70.00%, 68.18%, 59.05%, and 40.63%, respectively. L. plantarum KI134 (23.01%) showed higher adhesion ability than the positive control (16.32%) L. rhamnosus GG. These results demonstrated that milk fermented by L. plantarum KI134 demonstrated an anti-obesity effect under in vitro conditions, with confirmed potential as a probiotic.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.8
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• pp.989-995
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• 2009

Extract yield of tartary buckwheat treated with water, 70% ethanol or methanol were about 13.6%, 7.0% and 6.6%, respectively. Extract yield was greatly increased by the treatment of $\alpha$-amylase indicating 95.1% yield. $RC_{50}$ value of DPPH radical scavenging activity with methanol and 70% ethanol extracts were 34.0 $\mu g$/mL, 40.5 $\mu g$/mL, respectively. The DPPH radical scavenging activity increased when it was treated with $\beta$-glucosidase and cellulase, showing $RC_{50}$ value of 24.7 $\mu g$/mL and 25.0 $\mu g$/mL, respectively. In ABTS radical scavenging activity, methanol extract (100 $\mu g$/mL) showed 30% inhibition. In DPPH or ABTS radical scavenging activities, the treatment of $\beta$-glucanase and $\alpha$-amylase shows the highest and the lowest activities, respectively. In $\alpha$-glucosidase inhibitory effect, 70% ethanol extract showed $RC_{50}$ value of 59.9 $\mu g$/mL, but water extract was not inhibitory effective. The $\alpha$-glucosidase inhibitory effect was the highest in multi enzyme treatment. Content of rutin and quercetin in methanol extract showed higher value with 4400.3 mg% and 71.9 mg%, respectively. The 70% ethanol extract of buckwheat contained rutin of 3459.8 mg% and quercetin of 56.9 mg%. In the treatment of $\beta$-glucanase, the rutin content of ethanol extract increased with 5057.4 mg% and multi-enzyme treatment resulted in the modification of rutin glycoside.

• Journal of Applied Biological Chemistry
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• v.60 no.3
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• pp.283-291
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• 2017

Rice that the half of population in the world eats as a staple food is mostly produced and consumed in Asia. However, its consumption is nowadays decreasing mainly due to diet diversity. Accordingly, some attempts are in demand to enhance the utilization of rice. In this study, profiling of volatile and non-volatile flavor components in rice pastes obtained by ${\alpha}$-amylase was performed and compared according to nine different rice cultivars domestically cultivated in Korea using gas chromatography-mass spectrometry combined by solid phase microextraction and gas chromatography-time of flight-mass spectrometry after a derivatization, respectively. In total, 46 volatile compounds identified included 6 alcohols, 6 aldehydes, 4 esters, 4 furan derivatives, 4 ketones, 1 acid, 1 sulfur-containing compound, 7 hydrocarbons, 5 aromatics and 8 terpenes. The non-volatile flavor components found were composed of 12 amino acids, 6 sugars and 4 sugar alcohols. In principal component analysis, rice paste samples could be discriminated according to cultivars on the score plots of volatile and non-volatile flavor compounds. In particular, some volatile compounds such as pentanal and 4,7-dimethylundecane could contribute to distinguish Senong 17 white and Senong 17 brown, whereas ethanol, 6-methylhep-5-en-2-one, and tridecane could be highly related to the discrimination of Iipum from other cultivars. Among non-volatile compounds, some amino acids such as glycine, serine and ${\gamma}$-aminobutyric acid and some sugars such as sucrose and fructose were mainly responsible for the discrimination of Danmi from the other cultivars. On the other hand, galactose, arabitol and mannose were more closely related to Senong 17 white than Senong 17 brown.

• Journal of the Korean Society of Tobacco Science
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• v.18 no.1
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• pp.49-53
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• 1996

This experiment was carried out to study the effect of oxygen on chemical composition and physical properties of tobacco leaves during flue-curing. The results obtained were as follows: Starch content decreased and sucrose content increased with increasing oxygen supply during curing. Glucose and fructose of the cured leaves showed high content at the 5-10% oxygen supply. Amino-N and nitrate-N increased with increasing oxygen supply. Total nitrogen and NH4-N showed the lowest value at the 5-10% and 10-15% oxygen supply in the cutters and leaf, respectively. Chlorophyll and chlorogenic acid increased, and total volatile base decreased with increasing oxygen supply. The activity of α-amylase increased at the latter period of flue-curing, and the maximum activity point were delayed 12 hours with increasing oxygen supply. Shatter index of cured leaves decreased with increasing oxygen supply. It was desirable to supply oxygen during flue-curing for the improvement of chemical and physical properties such as starch, total sugar, chlorogenic acid, and shatter index of cured leaves.

• Food Science of Animal Resources
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• v.41 no.1
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• pp.164-171
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• 2021

Listeria monocytogenes is a representative foodborne pathogen and causes listeriosis. Enterococcus faecium CJNU 2524 was confirmed to produce a bacteriocin with anti-listerial activity. To establish optimal culture conditions for the production of the bacteriocin from E. faecium CJNU 2524, different media (MRS and BHI broth) and temperatures (25℃, 30℃, and 37℃) were investigated. The results showed that the optimal culture conditions were MRS broth and 25℃ or 30℃ temperatures. The crude bacteriocin was stable in a broad range of pH conditions (2.0-10.0), temperatures (60℃-100℃), and organic solvents (methanol, ethanol, acetone, acetonitrile, and chloroform). The bacteriocin activity was abolished when treated with protease but not α-amylase or lipase, indicating the proteinaceous nature of the bacteriocin. Finally, the bacteriocin showed a bactericidal mode of action against L. monocytogenes. Therefore, it can be a biopreservative candidate for controlling L. monocytogenes in dairy and meat products.