Preliminary Investigation on the Action Modes of an Oligosaccharide-Producing Multifunctional Amylase |
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Authors: | Yang Wang Fan Li Yingjiu Zhang |
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Institution: | (1) Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, Jilin University, Changchun, 130021, People’s Republic of China; |
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Abstract: | The action modes of an oligosaccharide-producing multifunctional amylase (OPMA) were investigated using glucose and some oligosaccharides
as its substrates. OPMA did not cause the hydrolysis of maltose or isomaltose, but it catalyzed the α-1,6-transglycosylation
of maltose to produce isomaltose or did the self-condensation of isomaltose to form isomaltotetraose and 4-O-α-isomaltosyl
isomaltose. OPMA exhibited strong α-1,6-transglycosylation activity in addition to its α-1,4-hydrolytic activity on higher
oligosaccharides substrates rather than bisaccharides. OPMA displayed high acceptor specificity in its transglycosylation
or condensation reaction. OPMA seemed to only take glucose or isomaltose as the acceptor molecule in its transglycosylation
or condensation reaction, which made glucose or isomaltose form higher products, and as a result, glucose or isomaltose were
absent in the final products. In view of the simultaneously formation of several transglycosylation or condensation products,
it was predicted that there might be separate donor and acceptor sites in OPMA’s active center and the fact that the catalytically
active form of this enzyme included its homodimer or homotrimer supported this prediction. Accordingly, a special pathway,
isomaltose pathway, for OPMA catalysis was proposed to emphasize the central or important signification of isomaltose in OPMA
catalysis. |
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