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KMID : 0545120070170050792
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Journal of Microbiology and Biotechnology
2007 Volume.17 No. 5 p.792 ~ p.799
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Cloning and Characterization of Glycogen-Debranching Enzyme from Hyperthermophilic Archaeon Sulfolobus shibatae
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VAN TRINH THI KIM
Ryu Soo-In
Lee Kyung-Ju
Kim Eun-Ju
Lee Soo-Bok
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Abstract
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A gene encoding a putative glycogen-debranching enzyme in Sulfolobus shibatae (abbreviated as SSGDE) was cloned and expressed in Escherichia coli. The recombinant enzyme was purified to homogeneity by heat treatment and Ni-NTA affinity chromatography. The recombinant SSGDE was extremely thermostable, with an optimal temperature at 85oC. The enzyme had an optimum pH of 5.5 and was highly stable from pH 4.5 to 6.5. The substrate specificity of SSGDE suggested that it possesses characteristics of both amylo-1,6- glucosidase and α-1,4-glucanotransferase. SSGDE clearly hydrolyzed pullulan to maltotriose, and 6-O-α-maltosyl-β- cyclodextrin (G2-β-CD) to maltose and β-cyclodextrin. At the same time, SSGDE transferred maltooligosyl residues to the maltooligosaccharides employed, and maltosyl residues to G2-β-CD. The enzyme preferentially hydrolyzed amylopectin, followed in a decreasing order by glycogen, pullulan, and amylose. Therefore, the present results suggest that the glycogendebranching enzyme from S. shibatae may have industrial application for the efficient debranching and modification of starch to dextrins at a high temperature.
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KEYWORD
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Sulfolobus shibatae, glycogen-debranching enzyme, amylo-1, 6-glucosidase, α-1, 4-glucanotransferase, hyperthermophilic enzyme
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