1wcq

Mutagenesis of the Nucleophilic Tyrosine in a Bacterial Sialidase to Phenylalanine.

spinqualitylabelsall models 1wcq, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1wcq is a 3 chain structure with sequence from Micromonospora viridifaciens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.1Å Ligands: DAN, GOL, NA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NANH_MICVI To release sialic acids for use as carbon and energy sources for this non-pathogenic bacterium while in pathogenic microorganisms, sialidases have been suggested to be pathogenic factors. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Mutants of the Micromonospora viridifaciens sialidase, Y370E and Y370F, are catalytically active retaining enzymes that operate by different mechanisms. Previous substitutions with smaller amino acids, including Y370D, yielded inverting sialidases. At least one water molecule can fit into the active-site cavity of this mutant and act as a nucleophile from the face opposite the leaving group (Biochemistry 2003, 42, 12 682). Thus, addition of a CH(2) unit (Asp versus Glu) changes the mechanism from inversion back to retention of configuration. Based on Bronsted beta(lg) values, it is proposed that the Y370E mutant reacts by a double-displacement mechanism (beta(lg) on k(cat)/K(m) -0.36+/-0.04) with Glu370 acting as the nucleophile. However, the Y370F mutant (beta(lg) on k(cat)/K(m) -0.79+/-0.12) reacts via a dissociative transition state. The crystal structure of the Y370F mutant complexed with 2-deoxy-2,3-dehydro-N-acetylneuraminic acid shows no significant active-site perturbation relative to the wild-type enzyme. Two nucleophilic mutants of the Micromonospora viridifaciens sialidase operate with retention of configuration by two different mechanisms.,Watson JN, Newstead S, Narine AA, Taylor G, Bennet AJ Chembiochem. 2005 Nov;6(11):1999-2004. PMID:16206228 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Neuraminidase 3D structures

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