2d2o: Difference between revisions

[[Image:2d2o.gif|left|200px]]<br /><applet load="2d2o" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

2D2O is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermoactinomyces_vulgaris Thermoactinomyces vulgaris] with <scene name='pdbligand=CA:'>CA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Neopullulanase Neopullulanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.135 3.2.1.135] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2D2O OCA].  

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