1g5a: Difference between revisions

Revision as of 17:09, 2 May 2008

AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA

OverviewOverview

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.

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 Page seeded by OCA on Fri May 2 17:09:10 2008

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OCA

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 [[Image:1g5a.jpg|left|200px]]
- {{Structure
+<!--
-|PDB= 1g5a |SIZE=350|CAPTION= <scene name='initialview01'>1g5a</scene>, resolution 1.40&Aring;
+The line below this paragraph, containing "STRUCTURE_1g5a", creates the "Structure Box" on the page.
-|SITE=
+You may change the PDB parameter (which sets the PDB file loaded into the applet)
-|LIGAND= <scene name='pdbligand=EPE:4-(2-HYDROXYETHYL)-1-PIPERAZINE+ETHANESULFONIC+ACID'>EPE</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=TRS:2-AMINO-2-HYDROXYMETHYL-PROPANE-1,3-DIOL'>TRS</scene>
+or the SCENE parameter (which sets the initial scene displayed when the page is loaded),
-|ACTIVITY= <span class='plainlinks'>[http://en.wikipedia.org/wiki/Amylosucrase Amylosucrase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.4.1.4 2.4.1.4] </span>
+or leave the SCENE parameter empty for the default display.
-|GENE=
+-->
-|DOMAIN=
+{{STRUCTURE_1g5a|  PDB=1g5a  |  SCENE=  }}
-|RELATEDENTRY=
-|RESOURCES=<span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1g5a FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1g5a OCA], [http://www.ebi.ac.uk/pdbsum/1g5a PDBsum], [http://www.rcsb.org/pdb/explore.do?structureId=1g5a RCSB]</span>
-}}
 '''AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA'''
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 [[Category: Skov, L K.]]
 [[Category: Willemot, R M.]]
-[[Category: (beta-alpha)8 barrel]]
+[[Category: Glycoside hydrolase]]
-[[Category: glycoside hydrolase]]
+[[Category: Glycosyltransferase]]
-[[Category: glycosyltransferase]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May  2 17:09:10 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Mar 30 20:36:54 2008''