1t6p

Crystal Structure of Phenylalanine Ammonia Lyase from Rhodosporidium toruloides

spinqualitylabelsall models 1t6p, resolution 2.70Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1t6p is a 8 chain structure with sequence from Rhodotorula toruloides. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.7Å Ligands: 175, MSE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PALY_RHOTO Catalyzes the non-oxidative deamination of L-phenylalanine and L-tyrosine to form trans-cinnamic acid and p-coumaric acid respectively with similar efficiencies. Facilitates the commitment step in phenylpropanoid pathways that produce lignins, coumarins and flavonoids. 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 The first three-dimensional structure of phenylalanine ammonia lyase (PAL) has been determined at 2.1 A resolution for PAL from Rhodosporidium toruloides. The enzyme is structurally similar to the mechanistically related histidine ammonia lyase (HAL), with PAL having an additional approximately 160 residues extending from the common fold. We propose that catalysis (including lowering the pK(a) of nonacidic C3 of l-phenylalanine for an E1cb mechanism) is potentially governed by dipole moments of seven alpha helices associated with the PAL active site (six positive poles and one negative pole). Cofactor 3,5-dihydro-5-methylidene-4H-imidazol-4-one (MIO) resides atop the positive poles of three helices, for increasing its electrophilicity. The helix dipoles appear fully compatible with a model of phenylalanine docked in the active site of PAL having the first covalent bond formed between the amino group of substrate and the methylidene group of MIO: 12 highly conserved residues (near the N termini of helices for enhancing function) are poised to serve roles in substrate recognition, MIO activation, product separation, proton donation, or polarizing electrons from the phenyl ring of substrate for activation of C3; and a highly conserved His residue (near the C terminus of the one helix that directs its negative pole toward the active site to increase the residue's basicity) is positioned to act as a general base, abstracting the pro-S hydrogen from C3 of substrate. A similar mechanism is proposed for HAL, which has a similar disposition of seven alpha helices and similar active-site residues. The helix dipoles appear incompatible with a proposed mechanism that invokes a carbocation intermediate. Crystal structure of phenylalanine ammonia lyase: multiple helix dipoles implicated in catalysis.,Calabrese JC, Jordan DB, Boodhoo A, Sariaslani S, Vannelli T Biochemistry. 2004 Sep 14;43(36):11403-16. PMID:15350127 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Aminomutase 3D structures

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