2d2o
From Proteopedia
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Structure of a complex of Thermoactinomyces vulgaris R-47 alpha-amylase 2 with maltohexaose demonstrates the important role of aromatic residues at the reducing end of the substrate binding cleft
Overview
Thermoactinomyces vulgaris R-47 alpha-amylase 2 (TVAII) can efficiently, hydrolyze both starch and cyclomaltooligosaccharides (cyclodextrins). The, crystal structure of an inactive mutant TVAII in a complex with, maltohexaose was determined at a resolution of 2.1A. TVAII adopts a, dimeric structure to form two catalytic sites, where substrates are found, to bind. At the catalytic site, there are many hydrogen bonds between the, enzyme and substrate at the non-reducing end from the hydrolyzing site, but few hydrogen bonds at the reducing end, where two aromatic residues, Trp356 and Tyr45, make effective interactions with a substrate. Trp356, drastically changes its side-chain conformation to achieve a strong, stacking interaction with the substrate, and Tyr45 from another molecule, forms a water-mediated hydrogen bond with the substrate. Kinetic analysis, of the wild-type and mutant enzymes in which Trp356 and/or Tyr45 were, replaced with Ala suggested that Trp356 and Tyr45 are essential to the, catalytic reaction of the enzyme, and that the formation of a dimeric, structure is indispensable for TVAII to hydrolyze both starch and, cyclodextrins.
About this Structure
2D2O is a Single protein structure of sequence from Thermoactinomyces vulgaris with CA as ligand. Active as Neopullulanase, with EC number 3.2.1.135 Full crystallographic information is available from OCA.
Reference
Structure of a complex of Thermoactinomyces vulgaris R-47 alpha-amylase 2 with maltohexaose demonstrates the important role of aromatic residues at the reducing end of the substrate binding cleft., Ohtaki A, Mizuno M, Yoshida H, Tonozuka T, Sakano Y, Kamitori S, Carbohydr Res. 2006 Jun 12;341(8):1041-6. Epub 2006 Mar 27. PMID:16564038
Page seeded by OCA on Wed Nov 21 09:24:21 2007
