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| == Function == | | == Function == |
| [https://www.uniprot.org/uniprot/GLGB_ORYSJ GLGB_ORYSJ] Catalyzes the formation of the alpha-1,6-glucosidic linkages in starch by scission of a 1,4-alpha-linked oligosaccharide from growing alpha-1,4-glucan chains and the subsequent attachment of the oligosaccharide to the alpha-1,6 position. | | [https://www.uniprot.org/uniprot/GLGB_ORYSJ GLGB_ORYSJ] Catalyzes the formation of the alpha-1,6-glucosidic linkages in starch by scission of a 1,4-alpha-linked oligosaccharide from growing alpha-1,4-glucan chains and the subsequent attachment of the oligosaccharide to the alpha-1,6 position. |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| Starch-branching enzyme catalyzes the cleavage of alpha-1, 4-linkages and the subsequent transfer of alpha-1,4 glucan to form an alpha-1,6 branch point in amylopectin. Sequence analysis of the rice-branching enzyme I (BEI) indicated a modular structure in which the central alpha-amylase domain is flanked on each side by the N-terminal carbohydrate-binding module 48 and the alpha-amylase C-domain. We determined the crystal structure of BEI at a resolution of 1.9 A by molecular replacement using the Escherichia coli glycogen BE as a search model. Despite three modular structures, BEI is roughly ellipsoidal in shape with two globular domains that form a prominent groove which is proposed to serve as the alpha-polyglucan-binding site. Amino acid residues Asp344 and Glu399, which are postulated to play an essential role in catalysis as a nucleophile and a general acid/base, respectively, are located at a central cleft in the groove. Moreover, structural comparison revealed that in BEI, extended loop structures cause a narrowing of the substrate-binding site, whereas shortened loop structures make a larger space at the corresponding subsite in the Klebsiella pneumoniae pullulanase. This structural difference might be attributed to distinct catalytic reactions, transglycosylation and hydrolysis, respectively, by BEI and pullulanase.
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| Crystal structure of the branching enzyme I (BEI) from Oryza sativa L with implications for catalysis and substrate binding.,Noguchi J, Chaen K, Vu NT, Akasaka T, Shimada H, Nakashima T, Nishi A, Satoh H, Omori T, Kakuta Y, Kimura M Glycobiology. 2011 Aug;21(8):1108-16. Epub 2011 Apr 14. PMID:21493662<ref>PMID:21493662</ref>
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| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| <div class="pdbe-citations 3amk" style="background-color:#fffaf0;"></div>
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| == References ==
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| <references/>
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| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |
