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Characterization of an α-glucosidase, HdAgl, from the digestive fluid of Haliotis discus hannai

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Title: Characterization of an α-glucosidase, HdAgl, from the digestive fluid of Haliotis discus hannai
Authors: Satoh, Takuya Browse this author
Inoue, Akira Browse this author →KAKEN DB
Ojima, Takao Browse this author →KAKEN DB
Keywords: Gastropod
Issue Date: Sep-2013
Publisher: Elsevier
Journal Title: Comparative biochemistry and physiology b : biochemistry & molecular biology
Volume: 166
Issue: 1
Start Page: 15
End Page: 22
Publisher DOI: 10.1016/j.cbpb.2013.06.002
PMID: 23774639
Abstract: Previously, we isolated two alpha-amylase isozymes, HdAmy58 and HdAmy82, from the digestive fluid of the Pacific abalone Haliotis discus hannai (Kumagai et al., 2013, Comp. Biochem. Physiol., B 164, 80-88). These enzymes degraded starch producing maltooligosaccharides but not glucose. However, the digestive fluid itself could produce glucose from starch, indicating that the digestive fluid contains alpha-glucosidase-like enzymes together with the alpha-amylases. Thus, in the present study, we isolated this alpha-glucosidase-like enzyme from the digestive fluid and characterized it to some extent. Isolation of this enzyme was carried out by ammonium sulfate fractionation followed by conventional column chromatographies and FPLC. The purified enzyme showed an apparent molecular mass of 97 kDa on SDS-PAGE, and optimal temperature and pH of 45 degrees C and 3.8-5.5, respectively. This enzyme could degrade various sizes of maltooligosaccharides into glucose and released glucose from starch producing no appreciable intermediate oligosaccharides. We concluded that this enzyme is an alpha-glucosidase (EC exolitically acting on polymer substrate and named HdAgl. HdAgl efficiently degraded maltose but hardly degraded p-nitrophenyl alpha - D-glucopyranoside (alpha-pNPG) and isomaltose. This enzyme was regarded as a maltase-like alpha-glucosidase that preferably degrades maltose but scarcely aryl glucosides. When starch was used as a substrate, HdAgl converted approximately 40% (w/w) of the starch to glucose. If an abalone alpha-amlylase HdAmy58 was added to the reaction mixture, the glucose yield increased to 60% (w/w). These results suggested that both HdAgl and HdAmy58 play important roles for the production of glucose from dietary starch in the digestive fluid. The amino-acid sequence of 887 residues for HdAgl was deduced by the cDNA method. This sequence showed 41-46% amino-acid identities to those of mammalian and avian alpha-glucosidases belonging to glycoside-hydrolase-family31. (C) 2013 Elsevier Inc. All rights reserved.
Type: article (author version)
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 尾島 孝男

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