1one
From Proteopedia
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YEAST ENOLASE COMPLEXED WITH AN EQUILIBRIUM MIXTURE OF 2'-PHOSPHOGLYCEATE AND PHOSPHOENOLPYRUVATE
Overview
The equilibrium mixture of yeast enolase with substrate, 2-phospho-D-glycerate (2-PGA), and product, phosphoenolpyruvate, (P-enolpyruvate), has been crystallized from solutions of poly(ethylene, glycol) (PEG) at pH 8.0. Crystals belong to the space group C2 and have, unit cell dimensions a = 121.9 A, b = 73.2 A, c = 93.9 A, and beta = 93.3, degrees. The crystals have one dimer per asymmetric unit. Crystals of the, equilibrium mixture and of the enolase complex of, phosphonoacetohydroxamate (PhAH) are isomorphous, and the structure of the, former complex was solved from the coordinates of enolase-(Mg2+)2-PhAH, [Wedekind, J. E., Poyner, R. R., Reed, G. H., & Rayment, I. (1994), Biochemistry 33, 9333-9342]. The current crystallographic R-factor is, 17.7% for all recorded data (92% complete) to 1.8 A resolution. The, electron density map is unambiguous with respect to the positions and, liganding of both magnesium ions and with respect to the stereochemistry, of substrate/product binding. Both magnesium ions are complexed to, functional groups of the substrate/product. The higher affinity Mg2+, coordinates to the carboxylate side chains of Asp 246, Glu 295, and Asp, 320, both carboxylate oxygens of the substrate/product, and a water, molecule. One of the carboxylate oxygens of the substrate/product also, coordinates to the lower affinity Mg2+-thus forming a mu-carboxylato, bridge. The other ligands of the second Mg2+ are a phosphoryl oxygen of, the substrate/product, two water molecules, and the carbonyl and, gamma-oxygens of Ser 39 from the active site loop. The intricate, coordination of both magnesium ions to the carboxylate group suggests that, both metal ions participate in stabilizing negative charge in the, carbanion (aci-carboxylate) intermediate. The epsilon-amino group of Lys, 345 is positioned to serve as the base in the forward reaction whereas the, carboxylate side chain of Glu 211 is positioned to interact with the 3-OH, of 2-PGA. The structure provides a candid view of the catalytic machinery, of enolase.
About this Structure
1ONE is a Single protein structure of sequence from Saccharomyces cerevisiae with MG and PEP as ligands. Active as Phosphopyruvate hydratase, with EC number 4.2.1.11 Full crystallographic information is available from OCA.
Reference
A carboxylate oxygen of the substrate bridges the magnesium ions at the active site of enolase: structure of the yeast enzyme complexed with the equilibrium mixture of 2-phosphoglycerate and phosphoenolpyruvate at 1.8 A resolution., Larsen TM, Wedekind JE, Rayment I, Reed GH, Biochemistry. 1996 Apr 9;35(14):4349-58. PMID:8605183
Page seeded by OCA on Tue Nov 20 23:02:14 2007
