1dtn

MANDELATE RACEMASE MUTANT D270N CO-CRYSTALLIZED WITH (S)-ATROLACTATEMANDELATE RACEMASE MUTANT D270N CO-CRYSTALLIZED WITH (S)-ATROLACTATE

Structural highlights 1dtn is a 1 chain structure with sequence from "bacillus_aeruginosus"_(schroeter_1872)_trevisan_1885 "bacillus aeruginosus" (schroeter 1872) trevisan 1885. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: , Gene: MANDELATE RACEMASE ("Bacillus aeruginosus" (Schroeter 1872) Trevisan 1885) Activity: Mandelate racemase, with EC number 5.1.2.2 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum 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 In the high-resolution X-ray structure of mandelate racemase (MR) with the competitive inhibitor (S)-atrolactate bound in the active site [Landro, J. A., Gerlt, J. A., Kozarich, J. W., Koo, C. W., Shah, V. J., Kenyon, G. L., Neidhart, D. J., Fujita, J., & Petsko, G. A. (1994) Biochemistry 33, 635-643], the carboxylic acid group of Glu 317 is hydrogen-bonded to the carboxylate group of the bound inhibitor. This geometry suggests that the carboxylic acid functional group of Glu 317 participates as a general acid catalyst in the concerted general acid-general base catalyzed formation of a stabilized enolic tautomer of mandelic acid as a reaction intermediate. To test this hypothesis, the E317Q mutant of MR was constructed and subjected to high-resolution X-ray structural analysis in the presence of (S)-atrolactate. No conformational alterations were observed to accompany the E317Q substitution at 2.1 A resolution. The values for kcat were reduced 4.5 x 10(3)-fold for (R)-mandelate and 2.9 x 10(4)-fold for (S)-mandelate; the values for kcat/Km were reduced 3 x 10(4)-fold. The substrate and solvent deuterium isotope effects measured for both wild-type MR and the E317Q mutant are not multiplicative when deuteriated substrate is studied in D2O, which suggests that the reactions catalyzed by both enzymes are stepwise and involve the formation of stabilized enolic intermediates. In contrast to wild-type MR, E317Q does not catalyze detectable elimination of bromide ion from either enantiomer of p-(bromomethyl)mandelate. However, E317Q is irreversibly inactivated by racemic alpha-phenylglycidate at a rate comparable to that measured for wild-type MR. Taken together, these mechanistic properties confirm the importance of Glu 317 as a general acid catalyst in the reaction catalyzed by wild-type MR. The kcat for wild-type MR and the reduction in kcat observed for E317O are discussed in terms of the analysis recently described by Gerlt and Gassman for understanding the rates and mechanisms of enzyme-catalyzed proton abstraction reactions from carbon acids [Gerlt, J. A., & Gassman, P. G. (1993) J. Am. Chem. Soc. 115, 11552-11568; Gerlt, J. A., & Gassman, P. G. (1993) Biochemistry 32, 11943-11952]. Mechanism of the reaction catalyzed by mandelate racemase: importance of electrophilic catalysis by glutamic acid 317.,Mitra B, Kallarakal AT, Kozarich JW, Gerlt JA, Clifton JG, Petsko GA, Kenyon GL Biochemistry. 1995 Mar 7;34(9):2777-87. PMID:7893689 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Mandelate racemase

spinqualitylabelsall models 1dtn, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image