Cassady sandbox1: Difference between revisions
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Glycolysis is an essential metabolic process for survival. Therefore, in its activation and suppression it must be highly regulated. Three points in the process of glycolysis occur with a large negative free energy and are therefore, irreversible. These three points are hexokinase, phosphofructokinase, and pyruvate kinase. These three reactions are candidates to be the major points of regulation, because they are they committed steps. Of the three PFK is considered the major regulatory point for glycolysis in muscle with a ΔG= -25.9 kJ/mol. <ref>Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry: Life at the Molecular Level. Hoboken, NJ: Wiley, 2008. Print.</ref>. This makes sense seeing as pyruvate kinase catalyzes the final reaction and hexokinase is an enzyme involved in more processes than glycolysis. | Glycolysis is an essential metabolic process for survival. Therefore, in its activation and suppression it must be highly regulated. Three points in the process of glycolysis occur with a large negative free energy and are therefore, irreversible. These three points are hexokinase, phosphofructokinase, and pyruvate kinase. These three reactions are candidates to be the major points of regulation, because they are they committed steps. Of the three PFK is considered the major regulatory point for glycolysis in muscle with a ΔG= -25.9 kJ/mol. <ref>Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry: Life at the Molecular Level. Hoboken, NJ: Wiley, 2008. Print.</ref>. This makes sense seeing as pyruvate kinase catalyzes the final reaction and hexokinase is an enzyme involved in more processes than glycolysis. | ||
PFK is regulated by ATP, AMP, ADP. While ATP binds at the active site | PFK is regulated by ATP, AMP, ADP. While ATP binds at the active site equally well in both R and T states, it preferentially binds the allosteric site of the T state <ref>Voet, Donald, Judith G. Voet, and Charlotte W. Pratt. Fundamentals of Biochemistry: Life at the Molecular Level. Hoboken, NJ: Wiley, 2008. Print.</ref> This preferential binding causes a shift from equilibrium of the two states, to a greater amount of T state <ref>PubMed:2136935</ref>, which decreases the affinity for F6P. Allosteric activator <scene name='Zach_Westrick_Sandbox/Allosteric_activator/2'>ADP</scene> also binds to allosteric site to increase the ratio of R state phosphofructokinase. | ||
The system of regulation matches perfectly with the function of PFK. When PFK is active, ATP is being produced down stream from it as glucose is eventually broken down completely. Thus, when ATP levels are low and more needs to be made, the activity of PFK will be increased, because ADP will be in high concentration. The opposite holds true as well, when ATP is in high concentration and inhibits protein activity. | The system of regulation matches perfectly with the function of PFK. When PFK is active, ATP is being produced down stream from it as glucose is eventually broken down completely. Thus, when ATP levels are low and more needs to be made, the activity of PFK will be increased, because ADP will be in high concentration. The opposite holds true as well, when ATP is in high concentration and inhibits protein activity. | ||
