Question

Although it is not the primary flux-control point for glycolysis, pyruvate kinase is subject to allosteric regulation. What is the metabolic importance of regulating flux through the pyruvate kinase reaction? As part of you answer, write a balanced equations for 1) the conversion of glucose to pyruvate and back to glucose & 2) the conversion of glucose to phosphoenolpyruvate and back to glucose.

Answer 1

Pyruvate kinase is a allosteric enzyme having modulator binding site and a substrate binding site which regulates the enzyme activity . Metabolic importance of regulating flux through pyruve kinase reaction is that pyruvate is to be converted into acetyl coenzyme A for kreb's cycle and also it is independent of oxygen.

Following flow chart shows the conversion of glucose to pyruvate and back to glucose and the conversion of glucose to phosphoenolpyruvate and back to glucose:

1)Glucose + 2(NAD+) + 2ADP + 2H2PO4- GIVES 2 pyruvate + 2NADH+ 2ATP + 2H2O.

2) Glucose + 2( NAD+) + 2H2PO4- GIVES Phosphoenolpyruvate + 2NADH + 2 H2O.