• Applied Biological Chemistry
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• v.31 no.4
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• pp.351-355
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• 1988

This study carried out to change ${\alpha}-amylase$ activity and isozymes in barley during germination in the dark and red light. The specific activity of ${\alpha}-amylase$ increased during the germination in the dark, giving 355.0 and 523.7 units/mg protein at 3 and 5 days, and the activity was increased by the red light up to 48 and 15% at 3 and 5 days of germination, respectively. The ratio of ${\alpha}-amylase$ I and II was approximately 95 : 5 at both 3 and 5 days of germination in the dark while the different ratio was found by the red light i.e. 60 : 40 and 90 : 10 at 3 and 5 days of germination, respectively.

• The Korean Journal of Food And Nutrition
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• v.3 no.1
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• pp.29-34
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• 1990

This study carried out to changes $\alpha$-amylase activity and isozymes in barley during germination in the dark and red light The specific activity of u-amylase was increased during the germination periods in the dark, giving 355.0 and 523.7 units/mg protein at 3 and 5 day, and the activity was increased by the red light up to 48 and 15% at 3 and 5 days of germination, respectively. The ratio of $\alpha$-amylase I and II was approximately 95:5 at both 3 and 5 days of germination in the dark while the different ratio was found by the red light i. e. 60 : 40 and 90 : 10 at 3 and 5 days of germination, respectively.

• 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.

• 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.