Primary Citation of Related Structures:   1ELS
PubMed Abstract: 
Enolase, a glycolytic enzyme that catalyzes the dehydration of 2-phospho-D-glycerate (PGA) to form phosphoenolpyruvate (PEP), requires two divalent metal ions per active site for activity. The first metal ion, traditionally referred to as "conformational", binds in a high-affinity site I ...
Enolase, a glycolytic enzyme that catalyzes the dehydration of 2-phospho-D-glycerate (PGA) to form phosphoenolpyruvate (PEP), requires two divalent metal ions per active site for activity. The first metal ion, traditionally referred to as "conformational", binds in a high-affinity site I. The second metal ion, "catalytic", binds in site II only in the presence of a substrate or substrate analogue and with much lower affinity for the physiological cofactor Mg2+. While the high-affinity site has been well characterized, the position of the lower affinity site has not been established so far. Here, we report the structure of the quaternary complex between enolase, the transition-state analogue phosphonoacetohydroxamate (PhAH), and two Mn2+ ions. The structure has been refined by using 16 561 reflections with F/sigma (F) > or = 3 to an R = 0.165 with average deviations of bond lengths and bond angles from ideal values of 0.013 A and 3.1 degrees, respectively. The "catalytic" metal ion is coordinated to two oxygen atoms of the phosphono moiety of PhAH and to the carbonyl oxygen of Gly37. Most likely, disordered water molecules complement its coordination sphere. The interaction with the site II metal ion must stabilize negative charge on the phosphate group and produce electron withdrawal from carbon 2 of the substrate, facilitating proton abstraction from carbon 2, the rate-limiting step in the catalytic process. The Gly37 residue is located in the flexible loop Ser36-His43, which assumes an "open" conformation in the absence of substrate and a "closed" conformation in the presence of a substrate.(ABSTRACT TRUNCATED AT 250 WORDS)
Related Citations: 
Fluoride Inhibition of Yeast Enolase: Crystal Structure of the Enolase-Mg2+-F--PI Complex at 2.6-Angstroms Resolution Lebioda, L., Zhang, E., Lewinski, K., Brewer, J.M. (1993) Proteins 16: 219
Mechanism of Enolase: The Crystal Structure of Enolase-Mg2+-Phosphoglycerate(Slash) Phosphoenolpyruvate Complex at 2.2-Angstroms Resolution Lebioda, L., Stec, B. (1991) Biochemistry 30: 2817
Inhibition of Enolase: The Crystal Structures of Enolase-Ca2+-Phosphoglycerate and Enolase-Zn2+-Phosphoglycolate Complexes at 2.2-Angstroms Resolution Lebioda, L., Stec, B., Brewer, J.M., Tykarska, E. (1991) Biochemistry 30: 2823
Refined Structure of Yeast Apo-Enolase at 2.25 Angstroms Resolution Stec, B., Lebioda, L. (1990) J Mol Biol 211: 235
Crystal Structure of Holoenzyme Refined at 1.9 Angstroms Resolution: Trigonal-Bipyramidal Geometry of the Cation Binding Site Lebioda, L., Stec, B. (1989) J Am Chem Soc 111: 8511
The Structure of Yeast Enolase at 2.25-Angstroms Resolution. An 8-Fold Beta+Alpha-Barrel with a Novel Beta Beta Alpha Alpha (Beta Alpha)6 Topology Lebioda, L., Stec, B., Brewer, J.M. (1989) J Biol Chem 264: 3685
Crystal Structure of Enolase Indicates that Enolase and Pyruvate Kinase Evolved from a Common Ancestor Lebioda, L., Stec, B. (1988) Nature 333: 683
Crystallization and Preliminary Crystallographic Data for a Tetragonal Form of Yeast Enolase Lebioda, L., Brewer, J.M. (1984) J Mol Biol 180: 213
Organizational Affiliation: 
Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208.