title: Effects of calcium ion concentration on starch hydrolysis of barley alpha-amylase isozymes.
abstract: Barley alpha-amylase genes, amy1 and amy2, were separately cloned into the expression vector of pPICZalphaA 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.
authors.affiliation: Department of Food Science and Technology, School of Applied Life Science and Environment, Chungbuk National University, Cheongju 361-763, Korea.
authors.forename: Jeong-Bin
authors.initials: JB
authors.lastname: Yuk
authors.forename: Seung-Ho
authors.initials: SH
authors.lastname: Choi
authors.forename: Tae-Hee
authors.initials: TH
authors.lastname: Lee
authors.forename: Myoung-Uoon
authors.initials: MU
authors.lastname: Jang
authors.forename: Jung-Mi
authors.initials: JM
authors.lastname: Park
authors.forename: Ah-Rum
authors.initials: AR
authors.lastname: Yi
authors.forename: Birte
authors.initials: B
authors.lastname: Svensson
authors.forename: Tae-Jip
authors.initials: TJ
authors.lastname: Kim
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003001:Cloning, Molecular; D005818:Genetic Engineering; D001467:Hordeum / Q000201:enzymology*; D006868:Hydrolysis; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D010843:Pichia / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D013213:Starch / Q000378:metabolism*; D013379:Substrate Specificity; D000516:alpha-Amylases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D013213:Starch; D000516:alpha-Amylases; D002118:Calcium