2drw: Difference between revisions

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

D-amino acid amidase (DAA) from Ochrobactrum anthropi SV3, which catalyzes the stereospecific hydrolysis of D-amino acid amides to yield the D-amino acid and ammonia, has attracted increasing attention as a catalyst for the stereospecific production of D-amino acids. In order to clarify the structure-function relationships of DAA, the crystal structures of native DAA, and of the D-phenylalanine/DAA complex, were determined at 2.1 and at 2.4 A resolution, respectively. Both crystals contain six subunits (A-F) in the asymmetric unit. The fold of DAA is similar to that of the penicillin-recognizing proteins, especially D-alanyl-D-alanine-carboxypeptidase from Streptomyces R61, and class C beta-lactamase from Enterobacter cloacae strain GC1. The catalytic residues of DAA and the nucleophilic water molecule for deacylation were assigned based on these structures. DAA has a flexible Omega-loop, similar to class C beta-lactamase. DAA forms a pseudo acyl-enzyme intermediate between Ser60 O(gamma) and the carbonyl moiety of d-phenylalanine in subunits A, B, C, D, and E, but not in subunit F. The difference between subunit F and the other subunits (A, B, C, D and E) might be attributed to the order/disorder structure of the Omega-loop: the structure of this loop cannot assigned in subunit F. Deacylation of subunit F may be facilitated by the relative movement of deprotonated His307 toward Tyr149. His307 N(epsilon2) extracts the proton from Tyr149 O(eta), then Tyr149 O(eta) attacks a nucleophilic water molecule as a general base. Gln214 on the Omega-loop is essential for forming a network of water molecules that contains the nucleophilic water needed for deacylation. Although peptidase activity is found in almost all penicillin-recognizing proteins, DAA lacks peptidase activity. The lack of transpeptidase and carboxypeptidase activities may be attributed to steric hindrance of the substrate-binding pocket by a loop comprised of residues 278-290 and the Omega-loop.

2DRW is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Ochrobactrum_anthropi Ochrobactrum anthropi] with <scene name='pdbligand=BA:'>BA</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. This structure supersedes the now removed PDB entry 2D83. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2DRW OCA].  

Crystal structure and functional characterization of a D-stereospecific amino acid amidase from Ochrobactrum anthropi SV3, a new member of the penicillin-recognizing proteins., Okazaki S, Suzuki A, Komeda H, Yamaguchi S, Asano Y, Yamane T, J Mol Biol. 2007 Apr 20;368(1):79-91. Epub 2006 Oct 26. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=17331533 17331533]

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