2vlh

Quinonoid intermediate of Citrobacter freundii tyrosine phenol-lyase formed with methionine

spinqualitylabelsall models 2vlh, resolution 1.95Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2vlh is a 2 chain structure with sequence from Citrobacter freundii. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.95Å Ligands: K, P33, PGE, PLP, PM9 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TPL_CITFR 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 Amino acid transformations catalyzed by a number of pyridoxal 5'-phosphate (PLP)-dependent enzymes involve abstraction of the Calpha proton from an external aldimine formed between a substrate and the cofactor leading to the formation of a quinonoid intermediate. Despite the key role played by the quinonoid intermediates in the catalysis by PLP-dependent enzymes, limited accurate information is available about their structures. We trapped the quinonoid intermediates of Citrobacter freundii tyrosine phenol-lyase with L-alanine and L-methionine in the crystalline state and determined their structures at 1.9- and 1.95-A resolution, respectively, by cryo-crystallography. The data reveal a network of protein-PLP-substrate interactions that stabilize the planar geometry of the quinonoid intermediate. In both structures the protein subunits are found in two conformations, open and closed, uncovering the mechanism by which binding of the substrate and restructuring of the active site during its closure protect the quinonoid intermediate from the solvent and bring catalytically important residues into positions suitable for the abstraction of phenol during the beta-elimination of L-tyrosine. In addition, the structural data indicate a mechanism for alanine racemization involving two bases, Lys-257 and a water molecule. These two bases are connected by a hydrogen bonding system allowing internal transfer of the Calpha proton. Insights into the catalytic mechanism of tyrosine phenol-lyase from X-ray structures of quinonoid intermediates.,Milic D, Demidkina TV, Faleev NG, Matkovic-Calogovic D, Antson AA J Biol Chem. 2008 Oct 24;283(43):29206-14. Epub 2008 Aug 20. PMID:18715865 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tyrosinase 3D structures

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