• Journal of Food Hygiene and Safety
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• v.6 no.3
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• pp.127-131
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• 1991

${\alpha}-amylase\;and\;{\beta}-amylase$ were extracted from barley and wheat malt, respectively. Their kinetic parameters on gultinous and nonglutinous rice starch were examined. During the germination of barley and wheat, the increaments of ATP levels were significant after 2-day germination and the levels were reduced after 5 days. The dry weights were decreased after 3 days. The activities of amylases were the highest for 6 days in the barley and wheat malt. As for ${\alpha}-amylase$, that the substrate affinity of barley malt on nonglutionous rice starch was greater than other cases. The $V_{max}$ values of ${\alpha}-amylase$ from wheat malt on either type of rice starch showed high, and from barley malt on nonglutinous rice starch were high. The ${\beta}-amylse$ from barley malt showed high substrate affinity on the glutinous rice starch, and $V_{max}$ value of the enzyme from wheat malt on glutinous rice starch was higher than other. The substrate efficiency ($V_{max}/K_{m}$) of ${\beta}-amylase$ on the non glutinous rice strach was better than other cases.

• Korean Journal of Food Science and Technology
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• v.31 no.6
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• pp.1421-1426
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• 1999

Sixteen domestic barley varieties and subsequently produced malts were evaluated for quality characteristics. Diastatic power(DP), complementary actions of amylases in malt, had a wide $variation(139{\sim}220^{\circ}L)$ among the barley varieties. Some 6-row barley varieties demonstrated significantly high DP values. ${\beta}-\;and\;{\alpha}-amylase$ activities in malts were also significantly influenced by barley varieties. Diastatic power was highly correlated with ${\beta}-amylase$ activity, indicating that the ${\beta}-amylase$ activity was a predominant factor determining saccharifying action in malt. Amylograph was used to indirectly estimate starch-degrading enzymatic activity, and the reduction in amylograph viscosity was associated with ${\alpha}-amylase$ activity. Barley quality factors in relation to enzymatic activity of malt were analyzed, and the barley variety with lower kernel weight and less plumper kernels tended to produce higher starch-degrading enzyme activity. Potential diastatic power, an estimate of bound ${\beta}-amylase$ in raw barley, was associated with diastatic power in the final malt. Potential diastatic power turned out to be an important factor for predicting good malting barley.

• Food Science and Preservation
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• v.1 no.2
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• pp.117-124
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• 1994

To investigate characterization of the ${\alpha}$-amylase inhibitors from cereals and legumes produced in Korea, inhibitory activities against ${\alpha}$-amylase with the inhibitor from barley(Hordeum vulgare), wheat(Triticum aestivun), black bean(Glycine max), bean(Cajanus cajon) and pea(Pisum sativum) were measured. Among the samples tested, inhibitors from naked barley and black bean(sabong) which showed the highest inhibitor activities of cereals and legumes, respectively, were characterized according to treatment condition. The results obtained were summarized as follows. During the germination of naked barley and black bean, ${\alpha}$-amylase activities were gradually increased but inhibitory activities against ${\alpha}$-amylases were decreased. Both activities were gradually decreased when naked barley and black bean were stored. More than 50% of activities of the inhibitors from naked barley and black bean were remained at 100$^{\circ}C$ for 15 min and 20 min, respectively, indicating that the inhibitor from black bean was more stable to heat than that of barley.

• Korean journal of food and cookery science
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• v.12 no.4
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• pp.522-534
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• 1996

The present study was conducted to investigate quality characteristics of Nochi made with malted barley flour with (Cl) and without hull (C2), comparing with Nochi that was treated with different sources of commercial amylases. There was higher level of moisture content (18.4%) in Nochi treated with fungal ${\alpha}$-amylase (FU) comparing with the other Nochi samples. However, Nochi that was treated with bacterial ${\alpha}$-amylase and ${\beta}$-amylase (BA-${\beta}$) had the lowest level of moisture content (11.2%). Nochi samples which were treated with thermostable ${\alpha}$-amylase and fungal ${\alpha}$-amylase(TE-FU) were different from traditional Nochi samples in mechanical characteristics. According to the results of sensory evaluation, Cl was similar to C2 except in cohesiveness and malt flavor. TE-FU and Bh-${\beta}$ were not different from traditional Nochi in cohesiveness, sweetness and overall desirability.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.3
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• pp.367-375
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• 1998

The physicochemical properties of the $\alpha$-amylase inhibitors from black bean and naked barley is Korea were investigated. Preincubation time for maximum inhibition was 30min and no activity change was seen after that time. Optimum pH of the $\alpha$-amylase inhibitors from the black bean and naked barley was pH 7.0 and the inhibitory activities were stable in the range of pH 6.0~8.0 in both phosphate and Tris-HCI buffer solutions. Both inhibitors maintained more than 50% of activity after incubation for 17 min at 7$0^{\circ}C$. The inhibitors from the black bean and naked barley maintained more than 50% of activities after treatment for 40 min and 30 min with pepsin, and 30 min and 50 min with trypsin, respectively. Both inhibitors functioned via a noncompetitive mechanism and were active against porcine pancreatic and human salivary $\alpha$-amylases. The activities of both inhibitors were linear for the ionic stength ranging from 0 to 0.9. The addition of 70 mM maltose to the reaction mixture caused a maximum increase in the relative activities of both inhibitors, but it did not affect the dissociation of the EI complex. The activities of both inhibitors were significantly enhanced by adding 1mM of K+ or Mg2+.

• 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.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.43 no.1
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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.

• Journal of Microbiology and Biotechnology
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• v.18 no.4
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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.

• Applied Biological Chemistry
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• v.27 no.2
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• pp.107-111
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• 1984

Changes of starch, soluble sugar and activities of amylase in germinating maize seeds were studied with comparison of germinating barley seeds. The starch in the endosperm was degraded slowly during the course of germination, and starch degradation of maize seeds compared with barley seed was found after 2 or 4 days of seed germination. There was a transient decline of soluble sugar come-its in ungerminated seed at early stages, followed by the rapid increase which concided with the degradation of starch. Activities of amylases were increased with the progress of germination, and maximum activities were founded after 8 days of seed germination. The higher activities of ${\alpha}$- and ${\beta}$-amylase were found at Hwang-ok maize and barley, respectively.

• 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.