1i2q

CRYSTAL STRUCTURE OF ESCHERICHIA COLI TRANSALDOLASE B MUTANT T156A

spinqualitylabelsall models 1i2q, resolution 2.05Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1i2q is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.05Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TALB_ECOLI Transaldolase is important for the balance of metabolites in the pentose-phosphate pathway.[HAMAP-Rule:MF_00492] 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 roles of invariant residues at the active site of transaldolase B from Escherichia coli have been probed by site-directed mutagenesis. The mutant enzymes D17A, N35A, E96A, T156A, and S176A were purified from a talB-deficient host and analyzed with respect to their 3D structure and kinetic behavior. X-ray analysis showed that side chain replacement did not induce unanticipated structural changes in the mutant enzymes. Three mutations, N35A, E96A, and T156A resulted mainly in an effect on apparent kcat, with little changes in apparent Km values for the substrates. Residues N35 and T156 are involved in the positioning of a catalytic water molecule at the active site and the side chain of E96 participates in concert with this water molecule in proton transfer during catalysis. Substitution of Ser176 by alanine resulted in a mutant enzyme with 2.5% residual activity. The apparent Km value for the donor substrate, fructose 6-phosphate, was increased nearly fivefold while the apparent Km value for the acceptor substrate, erythrose 4-phosphate remained unchanged, consistent with a function for S176 in the binding of the C1 hydroxyl group of the donor substrate. The mutant D17A showed a 300-fold decrease in kcat, and a fivefold increase in the apparent Km value for the acceptor substrate erythrose 4-phosphate, suggesting a role of this residue in carbon-carbon bond cleavage and stabilization of the carbanion/enamine intermediate. Identification of catalytically important residues in the active site of Escherichia coli transaldolase.,Schorken U, Thorell S, Schurmann M, Jia J, Sprenger GA, Schneider G Eur J Biochem. 2001 Apr;268(8):2408-15. PMID:11298760 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Transaldolase 3D structures

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