1g5a: Difference between revisions

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{{STRUCTURE_1g5a|  PDB=1g5a  |  SCENE=  }}  
{{STRUCTURE_1g5a|  PDB=1g5a  |  SCENE=  }}  


'''AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA'''
===AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA===




==Overview==
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Amylosucrase (E.C. 2.4.1.4) is a member of Family 13 of the glycoside hydrolases (the alpha-amylases), although its biological function is the synthesis of amylose-like polymers from sucrose. The structure of amylosucrase from Neisseria polysaccharea is divided into five domains: an all helical N-terminal domain that is not similar to any known fold, a (beta/alpha)(8)-barrel A-domain, B- and B'-domains displaying alpha/beta-structure, and a C-terminal eight-stranded beta-sheet domain. In contrast to other Family 13 hydrolases that have the active site in the bottom of a large cleft, the active site of amylosucrase is at the bottom of a pocket at the molecular surface. A substrate binding site resembling the amylase 2 subsite is not found in amylosucrase. The site is blocked by a salt bridge between residues in the second and eight loops of the (beta/alpha)(8)-barrel. The result is an exo-acting enzyme. Loop 7 in the amylosucrase barrel is prolonged compared with the loop structure found in other hydrolases, and this insertion (forming domain B') is suggested to be important for the polymer synthase activity of the enzyme. The topology of the B'-domain creates an active site entrance with several ravines in the molecular surface that could be used specifically by the substrates/products (sucrose, glucan polymer, and fructose) that have to get in and out of the active site pocket.
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{{ABSTRACT_PUBMED_11306569}}


==About this Structure==
==About this Structure==
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[[Category: Glycoside hydrolase]]
[[Category: Glycoside hydrolase]]
[[Category: Glycosyltransferase]]
[[Category: Glycosyltransferase]]
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Revision as of 04:26, 1 July 2008

File:1g5a.png

Template:STRUCTURE 1g5a

AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREAAMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA

Template:ABSTRACT PUBMED 11306569

About this StructureAbout this Structure

1G5A is a Single protein structure of sequence from Neisseria polysaccharea. Full crystallographic information is available from OCA.

ReferenceReference

Amylosucrase, a glucan-synthesizing enzyme from the alpha-amylase family., Skov LK, Mirza O, Henriksen A, De Montalk GP, Remaud-Simeon M, Sarcabal P, Willemot RM, Monsan P, Gajhede M, J Biol Chem. 2001 Jul 6;276(27):25273-8. Epub 2001 Apr 16. PMID:11306569

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