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KMID : 0545120080180040730
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Journal of Microbiology and Biotechnology
2008 Volume.18 No. 4 p.730 ~ p.734
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Effects of Calcium Ion Concentration on Starch Hydrolysis of Barley α-Amylase Isozymes
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Yuk Jeong-Bin
Choi Seung-Ho
Lee Tae-hee
Jang Myoung-Uoon
Park Jung-Mi
Yi Ah-Rum
Birte Svensson
Kim Tae-Jip
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Abstract
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Barley α-amylase genes, amy1 and amy2, were separately cloned into the expression vector of pPICZαA 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.
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KEYWORD
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Barley α-amylases, Pichia expression, calcium dependency, starch hydrolysis
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