1g5a
AMYLOSUCRASE FROM NEISSERIA POLYSACCHAREA
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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 with NA, TRS and EPE as ligands. Active as Amylosucrase, with EC number 2.4.1.4 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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