Regulation of phosphofructokinase

Fig. 2.6. Regulation of Phosphofructokinase from Bacillus stearothermophilus. The tetrameric phosphofructokinase is aUostericaUy regulated by ADP, Frc-6-phosphate, and phosphoenolpyruvate (PEP). The binding of ADP and Frc-6-phosphate converts the enzyme into the active R state. PEP binds to the T state and inhibits phosphofructokinase. The circles represent the R state, and the squares represent the T state of the enzyme.

Good examples are the regulation of phosphofructokinase (PFK) that catalyses the reaction... 

Why is AMP and not ADP the positive regulator of phosphofructokinase When ATP is being utilized rapidly, the enzyme adenylate kinase (Section 9.4) can form ATP from ADP by the following reaction ... 

Figure 16.17. Allosteric Regulation of Phosphofructokinase. A high level of ATP inhibits the enzyme by decreasing its affinity for fructose 6-phosphate. AMP diminishes and citrate enhances the inhibitory effect of ATP. 

Figure 16.19 Regulation of phosphofructokinase by fructose 2,6 bisphosphate. In high concentrations, fructose 6-phosphate F-6P) activates the enzyme phosphofructokinase (PFK) through an intermediary, fructose 2,6-bisphosphate (F-2.6-BP).

Narabayashi, H., Randolph Lawson, J. W., Uyeda, K. (1985). Regulation of phosphofructokinase in perfused rat heart. J. Biol. Chem. 269, 9750-9758. 

The mechanism for regulation of phosphofructokinase in other tissues has proved to be one of controlling the rate of enzyme activity by varying the binding to its substrate, D-fructose 6-phosphate. The solubilized enzyme from rhesus-monkey spermatozoa is found to pos-... 

Some positive regulators act by raising the affinity of all substrate binding sites (catalytic sites) to the maximum, independent of [S], thus destroying the cooperativity and raising the reaction rate at low [S], An example of this behavior is the regulation of phosphofructokinase by AMP (adenosine 5 -phosphate). 

Activity of glycolysis depends on adenylate energy charge (Figure 13.8) Allosteric Regulation of Phosphofructokinase... 

Sign in atwww.thomsonedu.com/login and explore a Biochemistry Interactive tutorial on the regulation of phosphofructokinase. 

Describe the allosteric regulation of phosphofructokinase. Explain the role of fructose 2,6-bisphosphate in its regulation. Describe the fused-domain structure of phosphofructokinase 2 (PFK2)/fructose bisphosphatase 2 that forms and degrades fructose 2,6-bisphosphate. 

Describe the roles of glycolysis, name its products, and describe the regeneration of NAD" under aerobic and anaerobic conditions. Outline the regulation of phosphofructokinase in the liver. 

Kfen, V. and Rehacek, Z. (1984) Feedforward regulation of phosphofructokinase in a submerged culture of Claviceps purpurea producing clavine alkaloids. Speculat. Sci. TechnoL, 7, 223—226. 

Regulation of phosphofructokinase is not enough to account for the inhibition of glucose utilization in aerobiosis. An additional link was needed. And it could not be understood without the realization that there is a glucose phosphorylation pathway that involves two steps a catalysed transport and an irreversible phosphorylation. Now, control of a pathway can take place either at the level of the first step or at the first irreversible step. Of the organisms more used in studies on the Pasteur effect, in animal cells the glucose phosphorylation pathway is feedback controlled by allosteric inhibition of hexokinase by glucose- P,... 

---