1qw9
From Proteopedia
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Crystal structure of a family 51 alpha-L-arabinofuranosidase in complex with 4-nitrophenyl-Ara
Overview
High-resolution crystal structures of alpha-L-arabinofuranosidase from, Geobacillus stearothermophilus T-6, a family 51 glycosidase, are, described. The enzyme is a hexamer, and each monomer is organized into two, domains: a (beta/alpha)8-barrel and a 12-stranded beta sandwich with, jelly-roll topology. The structures of the Michaelis complexes with, natural and synthetic substrates, and of the transient covalent, arabinofuranosyl-enzyme intermediate represent two stable states in the, double displacement mechanism, and allow thorough examination of the, catalytic mechanism. The arabinofuranose sugar is tightly bound and, distorted by an extensive network of hydrogen bonds. The two catalytic, residues are 4.7 A apart, and together with other conserved residues, contribute to the stabilization of the oxocarbenium ion-like transition, state via charge delocalization and specific protein-substrate, interactions. The enzyme is an anti-protonator, and a 1.7 A electrophilic, migration of the anomeric carbon takes place during the hydrolysis.
About this Structure
1QW9 is a Single protein structure of sequence from Geobacillus stearothermophilus with KHP as ligand. Active as Alpha-N-arabinofuranosidase, with EC number 3.2.1.55 Full crystallographic information is available from OCA.
Reference
Crystal structure and snapshots along the reaction pathway of a family 51 alpha-L-arabinofuranosidase., Hovel K, Shallom D, Niefind K, Belakhov V, Shoham G, Baasov T, Shoham Y, Schomburg D, EMBO J. 2003 Oct 1;22(19):4922-32. PMID:14517232
Page seeded by OCA on Wed Nov 21 01:03:29 2007
