Question

6-Phosphofructo-1-kinase activity can be decreased by all of the following except A. ATP at high concentrations. B. cirrate. \(\mathrm{C}_{1} \mathrm{AMP}\) D. low pH. E. decreased concentration of fructose 2,6 -bisphosphate.

Short answer

A. ATP at high concentrations B. Citrate C. AMP D. Low pH E. Decreased concentration of fructose 2,6-bisphosphate Answer: C. AMP

Step-by-step solution

Understand 6-Phosphofructo-1-kinase enzyme and its regulation

6-Phosphofructo-1-kinase (PFK-1) is an important enzyme in glycolysis that catalyzes the phosphorylation of fructose-6-phosphate to fructose-1,6-bisphosphate, utilizing one molecule of ATP. This reaction is a regulatory step in glycolysis. PFK-1 has several allosteric binding sites for various metabolites which regulate its activity. This helps maintain a balance between energy production and consumption in the cell.

Analyze the effects of each factor

A. ATP at high concentrations: ATP is a negative allosteric regulator of PFK-1. High levels of ATP will inhibit PFK-1's activity by binding to its allosteric site, causing a decrease in its activity. This makes sense since high ATP levels signify that the cell has enough energy and doesn't need to undergo glycolysis. B. Citrate: Citrate is an allosteric inhibitor of PFK-1. High levels of citrate inhibit PFK-1 activity, preventing the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate. This indicates that the cell has sufficient energy and metabolic intermediates, and glycolysis should be slowed down. C. AMP: AMP is an allosteric activator of PFK-1. High levels of AMP indicate that the cell needs more energy production, so it will increase the activity of PFK-1 to promote glycolysis. This implies that the presence of AMP will not decrease the enzyme's activity. D. Low pH: Low pH inhibits PFK-1 activity. The enzyme is sensitive to pH changes, and a decrease in pH can lead to a decrease in its catalytic activity. This could be a protective mechanism for the cell, as excessive glycolysis can lead to a decrease in pH (due to lactic acid production), which may induce damage. E. Decreased concentration of fructose 2,6-bisphosphate: Fructose 2,6-bisphosphate (F2,6BP) is a potent allosteric activator of PFK-1. A decrease in its concentration will reduce PFK-1's activity, resulting in a decrease in glycolysis.

Identify the statement that does not decrease activity

Based on the analysis of each factor's effects, we can conclude that statement C (AMP) does not decrease the activity of 6-Phosphofructo-1-kinase. In fact, AMP acts as an allosteric activator of the enzyme, promoting its activity and glycolysis when the cell needs more energy.