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Provedor de dados:  Inra
País:  France
Título:  Amylosucrase, a glucan-synthesizing enzyme from the α-amylase family
Autores:  Skov, L.K.
Mirza, O.
Henriksen, A.
Potocki de Montalk, G.
Remaud-Simeon, M.
Sarçabal, P.
Willemot, R.M.
Monsan, P.
Gajhede, M.
Data:  2001
Ano:  2001
Palavras-chave:  AMYLOSUCRASE
BACTERIE NON PATHOGENE
NEISSERIA POLYSACCHAREA
ALPHA AMYLASE
SACCHAROSE
STRUCTURE TRIDIMENSIONNELLE
GLYCOGENE
SEQUENCE NUCLEOTIDIQUE
ACTIVITE ENZYMATIQUE
GLYCOSIDE HYDROLYSE
NEISSERICEAE
BACTERIE GRAM NEGATIF
SUCRE
Resumo:  Amylosucrase (E.C. 2.4.1.4) is a member of Family 13 of the glycoside hydrolases (the α-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 (β/α)8-barrel A-domain, B- and B′-domains displaying α/β-structure, and a C-terminal eight-stranded β-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 (β/α)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.
Tipo:  Journal Article
Idioma:  Inglês
Identificador:  http://www.prodinra.inra.fr/prodinra/pinra/doc.xsp?id=PUB0400023316102157&uri=/notices/prodinra1/2010/10/

http://www.prodinra.inra.fr/prodinra/pinra/data/2010/10/PUB040002331610215_20101027092100258.pdf
Formato:  application/pdf
Fonte:  Journal of Biological Chemistry. 2001, 276 (27) : 25273-25278
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