Question

In: Chemistry

Which set of conditions would favor glycolysis in the reaction of fructose 6-phosphate and fructose 1,6-bisphosphate?...

Which set of conditions would favor glycolysis in the reaction of fructose 6-phosphate and fructose 1,6-bisphosphate?

1. high concentrations of ATP, Cirate and hydrogen ion

2. low concentrations of ATP, Cirate and hydrogen ion

3. high concentrations of acetyle CoA

4. low concentrations of glucose

Solutions

Expert Solution

The correct answer is 2 i.e . Low concentration of ATP,citrate and hydrogen ions favours the reaction fructose -6-phosphate to Fructose-1,6-bisphosphate ,which is catalysed by enzyme phosphofructokinase.

High levels of ATP allosterically inhibit the enzyme (phosphofructokinase)in the liver, thus lowering its affinity for fructose 6-phosphate. ATP elicits this effect by binding to a specific regulatory site that is distinct from the catalytic site. AMP reverses the inhibitory action of ATP, and so the activity of the enzyme increases when the ATP/AMP ratio is lowered. In other words, glycolysis is stimulated as the energy charge falls. A fall in pH also inhibits phosphofructokinase activity. The inhibition of phosphofructokinase by H+ prevents excessive formation of lactic acid and a precipitous drop in blood pH (acidosis).

phosphofructokinase is inhibited by citrate, an early intermediate in the citric acid cycle . A high level of citrate means that biosynthetic precursors are abundant and additional glucose should not be degraded for this purpose. Citrate inhibits phosphofructokinase by enhancing the inhibitory effect of ATP.


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