• Journal of Microbiology and Biotechnology
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• v.18 no.9
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• pp.1555-1563
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• 2008

A novel $\alpha$-amylase ($\alpha$-1,4-$\alpha$-D-glucan glucanohydrolase, E.C. 3.2.1.1), ScAmy43, was found in the culture medium of the phytopathogenic fungus Sclerotinia sclerotiorum grown on oats flour. Purified to homogeneity, ScAmy43 appeared as a 43 kDa monomeric enzyme, as estimated by SDS-PAGE and Superdex 75 gel filtration. The MALDI peptide mass fingerprint of ScAmy43 tryptic digest as well as internal sequence analyses indicate that the enzyme has an original primary structure when compared with other fungal a-amylases. However, the sequence of the 12 N-terminal residues is homologous with those of Aspergillus awamori and Aspergillus kawachii amylases, suggesting that the new enzyme belongs to the same GH13 glycosyl hydrolase family. Assayed with soluble starch as substrate, this enzyme displayed optimal activity at pH 4 and $55^{\circ}C$ with an apparent $K_m$ value of 1.66 mg/ml and $V_{max}$ of 0.1${\mu}mol$glucose $min^{-1}$ $ml^{-1}$. ScAmy43 activity was strongly inhibited by $Cu^{2+}$, $Mn^{2+}$, and $Ba^{2+}$, moderately by $Fe^{2+}$, and was only weakly affected by $Ca^{2+}$ addition. However, since EDTA and EGTA did not inhibit ScAmy43 activity, this enzyme is probably not a metalloprotein. DTT and $\beta$-mercaptoethanol strongly increased the enzyme activity. Starting with soluble starch as substrate, the end products were mainly maltotriose, suggesting for this enzyme an endo action.

• Applied Biological Chemistry
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• v.50 no.3
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• pp.198-203
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• 2007

Extracts from Schizandra chinensis Baillon (Korean name: Omija) were tested for antioxidant and their inhibitory activities of ${\alpha}-amylase$ and ${\alpha}-glucosidase$. Total contents of phenolics were found as 4.35 mg/g (water extract)${\sim}$6.35 mg/g (60% ethanol extract). Electron donating ability (EDA), ABTS [2,2'-azinobis(3-ethyl-benzothiaznoline-6-sulfonic acid)] radical decolorization, antioxidant protection factor (PF) and thiobarbituric acid reactive substance (TBARS) were measured for the antioxidative activity of the extracts from S. chinensis. The water extract were determined as 97.5% at 200 ${\mu}g/ml$ while the activity of 60% ethanol extract were 96.2% at 200 ${\mu}g/ml$ in EDA. The 60% ethanol extract showed higher antioxidant activity than water extract when evaluated by ABTS radical decolorization, antioxidant PF and TBARS. ${\alpha}-Amylase$ inhibitory activity of water extract was similar with that of 60% EtOH extract. ${\alpha}-glucosidase$ inhibitory activities of water extract (97.4%) was higher than that of 60% ethanol extract (84.5%) at 200 ${\mu}g$/ml. The water extract from S. chinensis did not show an antimicrobial activity against Helicobacter pylori, but the 60% ethanol extract showed high antimicrobial activities such as 23 ${\pm}$ 1.6 mm of clear zone in 200 ${\mu}g/ml$ of phenolics. The result suggest that the water and 60% ethanol extract from S. chinensis will be useful as natural antioxidants and functional foods.

• Food Science of Animal Resources
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• v.30 no.5
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• pp.795-803
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• 2010

A DF01 strain that inhibits tyramine-producing Lactobacillus curvatus KFRI 166 was isolated from Dongchimi, a traditional Korean fermented vegetable, and identified as Lactobacillus brevis by biochemical analysis and reverse transcriptase sequencing of 16S rRNA. The antimicrobial compound produced by L. brevis DF01 was secreted at a maximum level of 640 AU/mL in late exponential phase in MRS broth, and its activity remained constant during stationary phase. The activity of bacteriocin DF01 was totally inactivated by $\alpha$-chymotrypsin, pronase E, proteinase K, trypsin, and $\alpha$-amylase, but not by catalase, which indicates the compound was glycoprotein in nature. The activity was not affected by pH changes ranging from 2 to 12 or heat treatment (60, 80, and $100^{\circ}C$ for 30 min), but was reduced after autoclaving. Bacteriocin DF01 had bacteriolytic activity and a molecular weight of approximately 8.2 kDa, as shown by tricine-SDS-PAGE analysis. Therefore, bacteriocin DF01 can be used in the manufacture of fermented meat products due to its inhibition of tyramine-producing L. curvatus and non-inhibition of L. sake, which is used as a starter culture for meat fermentation.

• Journal of Microbiology and Biotechnology
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• v.22 no.5
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• pp.592-599
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• 2012

Bacillus licheniformis ${\alpha}$-amylase (BLA), a thermophilic counterpart of Bacillus amyloliquefaciens ${\alpha}$-amylase (BAA), is an appropriate model for the design of stabilizing mutations in BAA. BLA has 10 more histidines than BAA. Considering this prominent difference, in the present study, three out of these positions (I34, Q67, and P407; located in the thermostability determinant 1 region and Ca-III binding site of BAA) were replaced with histidine in BAA, using the site-directed mutagenesis technique. The results showed that the thermostability of P407H and Q67H mutants had increased, but no significant changes were observed in their kinetic parameters compared to that of the wild type. I34H replacement resulted in complete loss of enzyme activity. Moreover, fluorescence and circular dichroism data indicated a more rigid structure for the P407H variant compared with that of the wild-type BAA. However, the flexibility of Q67H and I34H mutants increased in comparison with that of wild-type enzyme.

• Journal of Animal Science and Technology
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• v.54 no.2
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• pp.133-139
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• 2012

A bacterium, identified as $Bacillus$ $amyloliquefacies$, CNL-90 using 16S rDNA analysis, was isolated from malt grain. The optimal activities of its ${\alpha}$-amylase and protease were observed at pH 6 and $60^{\circ}C$, and at pH 6 and $50^{\circ}C$, respectively although their activities remained stable at pH 7 and $40^{\circ}C$for ${\alpha}$-amylase and at pH 7 and $50^{\circ}C$ for protease. After solid-state fermentation of $B.$ $amyloliquefacies$, CNL-90 on wheat bran for 72hr or 144hr, the ${\alpha}$-amylase and protease activities were 170,000 and 290,000 units/kg, and 290,000 and 310,000 units/kg, respectively. The viable bacterial cell counts were $1.5{\times}10^9$ CFU/g and $2.2{\times}10^9$ CFU/g at 72hr and 144hr of the solid-state fermentation, respectively. A feeding trial with a total of 127 piglets was also conducted. The animals were divided into two groups: an experimental group fed with the fermented product (63 piglets) and a control group (64 piglets). The growth rate of the experimental group was 6.66% higher than that of the control group (P<0.05). The results of this study indicate that the ${\alpha}$-amylase and protease from $B.$ $amyloliquefacies$, CNL-90 can be used for industrial applications due to their activity in production of carbohydrate hydrolysates.

• Proceedings of the Korean Society of Crop Science Conference
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• 1999.05a
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• pp.128-129
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• 1999

• KSBB Journal
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• v.11 no.2
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• pp.132-139
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• 1996

The growth of recombinant E. coil and by-product production were investigated. D-cycloserine was added to increase the secretion of ${\alpha}$-amylase from recombinant E.coil. Even though cell growth was increased for optimal d-cycloserine concentration $0.1g/\ell$, extracellular ${\alpha}$-amylase activity remained almost the same as the case without d-cycloserine. It is important to achieve the high cell density for commercial production of methaboliles including ${\alpha}$-amylase. To achieve this goal, culture conditions should be selected carefully and optimized considering cell growth and by-products production. In cultivating retombinant E. coli, lactic acid and acetic acid turned out to be important by-product which affected cell yield and growth rate.

• Journal of Life Science
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• v.22 no.7
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• pp.920-927
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• 2012

The objective of this research was to develop the functional material of water and 60% ethanol extracts from nine kinds of mulberry fruits (Morus alba L.) that influence the inhibitory activity on angiotensin-converting enzyme, xanthine oxidase, ${\alpha}$-amylase, and ${\alpha}$-glucosidase. The total phenolic contents in the water extracts were over 2 mg/g in two species (Cheongilppong and Kangwon III) and five species (Daeyoupchosaeng, Cheongilppong, Kangwon III, Hihak, and Cataneo) of 60% ethanol extracts. The inhibitory activity against the angiotensin-converting enzyme was determined with them. Baekwoon III was $90.9{\pm}4.5%$ in the water extracts, and Hihak was $81.8{\pm}4.5%$ in the 60% ethanol extracts. The inhibitory activity of Kuksang 20 against xanthin oxidase was about 10% in the water extracts, and Cataneo was $21.4{\pm}2.3%$ in the 60% ethanol extracts. Six of the species (Daeyoupchosaeng, Suwonppong, Cheongilppong, Kangwon III, Hihak, and Kuksang 20) in the water extracts showed inhibitory activities against ${\alpha}$-amylase, as 100%, respectively. The inhibitory activity of ${\alpha}$-glucosidase was determined for these nine species. Four species (Baekwoon III, Daeyoupchosaeng, Cheongilppong, Kangwon III, Hihak, and Kuksang 20) in the water extracts and three species (Daechoukmyeun, Kangwon III, and Kuksang 20) in the 60% ethanol extracts showed inhibition of over 20%. The results revealed strong biological activity in spite of little total phenolic contents. These water and 60% ethanol extracts with high-quality biological activity from various mulberry fruits (Morus alba L.) are expected to represent good candidates for the development of antihypertentive and antidiabetes sources.

• BMB Reports
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• v.37 no.6
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• pp.642-647
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• 2004

The lysine residues of Bacillus licheniformis $\alpha$-amylase (BLA) were chemically modified using citraconic anhydride or succinic anhydride. Modification caused fundamental changes in the enzymes specificity, as indicated by a dramatic increase in maltosidase and a reduction in amylase activity. These changes in substrate specificity were found to coincide with a change in the cleavage pattern of the substrates and with a conversion of the native endo- form of the enzyme to a modified exo- form. Progressive increases in the productions of $\rho$-nitrophenol or glucose, when para nitrophenyl-maltoheptaoside or soluble starch, respectively, was used as substrate, were observed upon modification. The described changes were affected by the size of incorporated modified reagent: citraconic anhydride was more effective than succinic anhydride. Reasons for the observed changes are discussed and reasons for the effectivenesses of chemical modifications for tailoring enzyme specificities are suggested.

• Food Science and Preservation
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• v.17 no.4
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• pp.541-546
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• 2010

Wild-garlic (Allium victorialis L.) is a perennial plant found in worldwide and has been considered as a favorite vegetable due to its particular smell and taste. However, the study of biological activity of wild-garlic and the development of processed food are in rudimentary. In this study, we evaluated several biological activities, including antioxidant, antimicrobial, and inhibitory activities against human thrombin, $\alpha$-amylase and $\alpha$-glucosidase, of Ulrung wild-garlic. Analysis of the composition showed that Ulrung wild-garlic is nutritive although it is perishable. The color of fresh juice was stably maintained during 10 days-storage at $4^{\circ}C$, but rapidly discolored by heat treatment at $70^{\circ}C$ for 1 h. During heat treatment, the contents of total sugar and total polyphenol were decreased to 75% and 50%, respectively, and acidity was increased from 0.069% to 0.111%. In a while, the brix, reducing sugar, and total flavonoids showed minor changes. The fresh juice showed strong DPPH scavenging activity, reducing power and antibacterial and antifungal activity, but the heat-treated juice lost the antioxidant and antimicrobial activities. The inhibitory activities against human thrombin and $\alpha$-amylase and $\alpha$-glucosidase was negligible in both fresh juice and heat-treated juice. These results suggested that the antioxidant and antimicrobial components in wild-garlic are heat-liable and volatile. Based on our results, we propose non-heat treatment products for processed wild-garlic, for example, fresh juice-added beverage or fermented liquors using wild-garlic.