Phosphoenolpyruvate 2-phosphoglycerate

A. Phosphoenolpyruvate.—The mechanisms of hydrolysis of phosphate esters of phosphoenol pyruvic acid (33) have been described in detail, and 0 studies confirm an earlier postulate that attack by water on the cyclic acyl phosphate (34) occurs at phosphorus and not at carbon. In the enolase reaction, the reversible interconversion of 2-phosphoglyceric acid(35)... 

Larsen, T.M., Wedeking, J.E., Rayment, I. and Reed, G.H. (1996) 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, Biochemistry, 30, 4349-4358. 

Then follows an elimination reaction, in which water is removed from 2-phosphoglycerate to yield phosphoenolpyruvate. 

Blsphosphoglycerate ) 3-Phosphoglycerate ( 2-Phosphoglycerate Phosphoenolpyruvate Pyruvate Lactate... 

Enolase [EC 4.2.1.11] catalyzes the interconversion of 2-phosphoglycerate and phosphoenolpyruvate in a stepwise mechanism. Proton abstraction and at least one additional step (eg., hydroxide loss or product release) may limit the overall reaction rate. 

Figure 13.8 A 25-atom quantum subsystem embedded in an 8863-atom classical system to model the catalytic step in the conversion of D-2-phosphoglycerate to phosphoenolpyruvate by enolase. What factors influence the choice of where to set the boundary between the QM and MM regions Alhambra and co-workers found, using variational transition-state theory with a frozen MM region that was selected from a classical trajectory so as to make the reaction barrier and thermochemistry reasonable, that the breaking and making bond lengths were 1.75 and 1.12 A, respectively, for H, but 1.57 and 1.26 A, respectively, for D...

In the second glycolytic reaction that generates a compound with high phosphoryl group transfer potential, enolase promotes reversible removal of a molecule of water from 2-phosphoglycerate to yield phosphoenolpyruvate (PEP) ... 

Enolose. A key reaction in the metabolism of sugars is the dehydration of 2-phosphoglycerate to form phosphoenolpyruvate (PEP), the phospho derivative of the enolic form of pyruvic acid ... 

Phosphoenolpyruvate, a key metabolic intermediate. A compound of central importance in metabolism is the phosphate ester of the enol form of pyruvate, commonly known simply as phosphoenolpyruvate (PEP).249 It is formed in the glycolysis pathway by dehydration of 2-phosphoglycerate (Eq. 13-15) or by decarboxylation of oxaloacetate. Serving as a preformed enol from which a reactive enolate anion can be released for condensation reactions,250 251 PEP... 

Phosphoenolpyruvate phosphomutase Phosphoglucomutase Phosphoglycerate mutase (co-factor independent) Phosphoglycerate mutase (co-factor dependent)... 

The mixed anhydride of phosphoric acid and glyceric acid then is used to convert ADP to ATP and form 3-phosphoglycerate. Thereafter the sequence differs from that in photosynthesis. The next few steps accomplish the formation of pyruvate by transfer of the phosphoryi group from C3 to C2 followed by dehydration to phosphoenolpyruvate. Phosphoenolpyruvate is an effective phosphorylating agent that converts ADP to ATP and forms pyruvate ... 

The final energy payoff in the glycolytic pathway occurs in the hydrolysis of phosphoenolpyruvate to pyruvate and the concomitant phosphorylation of ADP to ATP. Two molecules of ATP are produced for each molecule of hexose phosphate consumed, bringing the net yield of ATP to two molecules for each molecule of glucose (two molecules of ATP are regenerated in the phosphoglycerate kinase step and two in this step, and two are consumed in the hexoki-nase and phosphofructokinase steps). 

Phosphoglycerate and phosphoenolpyruvate differ only by dehydration between C-2 and C-3, yet the difference in the A G° of hydrolysis is about... 

Elimination reactions occur in living organisms also. One important example is the conversion of 2-phosphoglycerate to phosphoenolpyruvate during the metabolism of glucose ... 

---