1ebh
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OCTAHEDRAL COORDINATION AT THE HIGH AFFINITY METAL SITE IN ENOLASE; CRYSTALLOGRAPHIC ANALYSIS OF THE MG++-ENZYME FROM YEAST AT 1.9 ANGSTROMS RESOLUTION
OverviewOverview
The structure of the Mg2+ complex of yeast enolase has been determined, from crystals grown in solutions of poly(ethylene glycol) at pH 8.1., Crystals belong to the space group P2(1) and have unit cell dimensions a =, 72.5 A, b = 73.2 A, c = 89.1 A, and beta = 104.4 degrees. There is one, dimer in the asymmetric unit. The current crystallographic R-factor is, 19.0% for all recorded data to 1.9 A resolution. The electron density, indicates a hexacoordinate Mg2+ at the high-affinity cation binding site., The octahedral coordination sphere consists of a meridional arrangement of, three carboxylate oxygens from the side chains of Asp 246, Asp 320, and, Glu 295, and three well-ordered water molecules. Octahedral coordination, is the preferred geometry for alkaline earth metal ions in complexes with, oxygen donor groups. In previous crystallographic studies of enolase, Zn2+, and Mg2+ complexes at the high-affinity site were reported to exist in, trigonal bipyramidal coordination. This geometry was suggested to enhance, the electrophilicity of the metal ion and promote rapid ligand exchange, [Lebioda, L., & Stec, B. (1989) J. Am. Chem. Soc. 111, 8511-8513]. The, octahedral arrangement of carboxylate and water ligands in the, MgII-enolase complex determined here is most consistent with reports of, the Mn2+ and Mg2+ coordination complexes of mandelate racemase and, muconate lactonizing enzyme. These latter enzymes have alpha/beta-barrel, folds comparable to enolase.(ABSTRACT TRUNCATED AT 250 WORDS)
About this StructureAbout this Structure
1EBH is a Single protein structure of sequence from Saccharomyces cerevisiae with CL and MG as ligands. Active as Phosphopyruvate hydratase, with EC number 4.2.1.11 Full crystallographic information is available from OCA.
ReferenceReference
Octahedral coordination at the high-affinity metal site in enolase: crystallographic analysis of the MgII--enzyme complex from yeast at 1.9 A resolution., Wedekind JE, Reed GH, Rayment I, Biochemistry. 1995 Apr 4;34(13):4325-30. PMID:7703246
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