Enzyme enolase

Another glycolytic enzyme, enolase, catalyzes the reversible dehydration of 2-phosphoglycerate to phospho-enolpyruvate ... 

CONTENTS Preface, C. Allen Bush. Thermodynamic Solvent Isotope Effects and Molecular Hydrophobicity, Terrence G. Oas and Eric J. Toone. Membrane Interactions of Hemolytic and Antibacterial Peptides, Karl Lohner and Richard M. Epand. Spin-Labeled Metabolite Analogs as Probes of Enzyme Structure, Chakravarthy Narasimhan and Henry M. Miziorko. Current Perspectives on the Mechanism of Catalysis by the Enzyme Enolase, John M. Brewer and Lukasz Leb-ioda. Protein-DNA Interactions The Papillomavirus E2 Proteins as a Model System, Rashmi S. Hedge. NMR-Based Structure Determination for Unlabeled RNA and DNA, Philip N. Borer, Lucia Pappalardo, Deborah J. Kenwood, and Istvan Pelczer. Evolution of Mononuclear to Binuclear CuA An EPR Study, William E. Antholine. Index. 

PEP is converted to fructose 1,6-bisphosphate in a series of steps that are a direct reversal of those in glycolysis (see Topic J3), using the enzymes enolase, phosphoglycerate mutase, phosphoglycerate kinase, glyceraldehyde 3-phosphate dehydrogenase, triose phosphate isomerase and aldolase (see Fig 1). This sequence of reactions uses one ATP and one NADH for each PEP molecule metabolized. 

Nittner-Marszalska, M., Wojcicka-Kustrzeba, I., Bogacka, E., Patkowski, J., and Dobek, R. 2001. Skin prick test response to enzyme enolase of the baker s yeast (Saccharomyces cerevisiae) in diagnosis of respiratory allergy. Med Sci. Monit 7(1) 121-124. 

This elimination is catalyzed by the enzyme enolase and follows an Elcb mechanism. The enzyme supplies a base to remove the acidic proton and generate a carbanion in the first step. In addition, a Mg2+ cation in the enzyme acts as a Lewis acid and bonds to the hydroxy group, making it a better leaving group. 

PEP is also used as an enol in the making of carbon-carbon bonds when the electrophile is a sugar molecule and we will see this reaction in the next chapter. So, if PEP is not made by enolization of pyruvate, how is it made The answer is by dehydration. The phosphate is already in place when the dehydration occurs, catalysed by the enzyme enolase. 

The glycolytic enzyme enolase (EC 4.2.1.11) catalyzes the interconversion of 2-phospho-D-glycerate and phosphoenolpymvate. Due to its essential role in glycolysis, enolase is a rather highly conserved enzyme, which has been identified and characterized from diverse sources ranging from bacteria to... 

Single cases of nitrofnrantoin-indnced (or enhanced) hemolytic anemia have occnrred in patients with deficiencies of other eiythrocyte enzymes (enolase or glutathione peroxidase), as have isolated cases of methemoglobinemia (42). 

The DNA content of mature Purkinje cells is high. Feulgen-DNA or propidiumiodide-DNA reveal hyperdiploid values (Bernocchi, 1986 Bernocchi et al., 1986). Purkinje cells stand out by their high content of enzymes, mostly dehydrogenases (Adams, 1965). Their content of the glycolytic enzyme enolase is low (Peic et al., 1986 Vinores et al.. 

Schmechel DE. Gamma subunit of the glycolytic enzyme enolase Nonspecific or neuron specific Lab Invest. 1985 52 239-242. 

NSE is a cytosolic isoenzyme of the glycolytic enzyme enolase, which catalyzes the conversion of... 

In this step the enzyme enolase catalyzes the dehydration (removal of a water molecule) of 2-phosphoglycerate. The energy-rich product is phosphoenolpyruvate, the highest energy phosphorylated compound in metabolism. 

The enzyme enolase catalyzes the interconversion of 2-phosphoglycerate and phosphoenolpymvate. 

Bucher (1947) studied a preparation of the crystalline mercury compound of the enzyme enolase, prepared in Warburg s laboratory. He obtained a molecular weight of 66,000, using edestin as a standard protein and assuming its molecular weight to be 300,000. The value... 

Then, in the presence of the enzyme enolase (phosphopyruvate hydratase, EC 4.2.1.11) and as shown in Scheme 11.25, dehydration of the 2-phospho-D-glycerate (2-phosphoglycerate) occurs to produce the phosphate enol of pyruvic acid, phos-phoenolpyruvate (PEP). 

The glycolytic enzyme enolase is inhibited by fluoride ions, which are rapidly taken into the cell in a lipid-soluble protonated form when the external pH is lower than the internal pH ... 

Dehydration reactions occur in many important biological processes. Instead of being catalyzed by strong acids, which would not be available to a cell, they are catalyzed by enzymes. Enolase, for example, catalyzes the dehydration of a-phosphoglycerate in glycolysis. Glycolysis is a series of reactions that prepare glucose for entry into the citric acid cycle (Section 25.7). 

Figure 6.2. Structure of the active site of an enzyme (enolase) showing the bound substrate and ait of the interactions between the substrate and residues in the active site of the protein. From Frey, P. A. Hegeman, A. D. Enzymatic Reaction Mechanisms, Oxford University...

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