Excess of ATP inhibits the enzyme –a)Phosphofructokinaseb)Hexokinasec)Aldolase (Lyases)d)Pyruvate decarboxylaseCorrect answer is option 'A'. Can you explain this answer?

Question

Excess of ATP inhibits the enzyme &#8211;a)Phosphofructokinaseb)Hexokinasec)Aldolase (Lyases)d)Pyruvate decarboxylaseCorrect answer is option 'A'. Can you explain this answer?

Answer

It's A. Cuz Phosphofructokinases - 1(PFK-1)is one of the most important regulatory enzymes of glycolysis.  It is an allosteric enzyme made up of 4 subunits and controlled by many activators n inhibitors. For example, a high ratio of ATP to ADP will inhibit PFK and glycolysis.

Answer

It is an allosteric enzyme. The ATP is an important allosteric inhibitor of this enzyme.Excess of ATP indicates energy surplus state and the need to shut or slow down further lysis of glucose. This is achieved by inhibiting phosphofructokinase in addition to inhibiting hexokinase and  pyruvate kinase.

Answer

Excess of ATP inhibits the enzyme Phosphofructokinase (PFK)

1. Overview of ATP and PFK

ATP (Adenosine triphosphate) is the primary energy currency of cells. It is involved in various cellular processes, including metabolism. Phosphofructokinase (PFK) is an important enzyme in the glycolysis pathway, which is responsible for breaking down glucose and producing ATP.

2. Role of PFK in Glycolysis

PFK catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, which is a key step in glycolysis. This step is irreversible and commits glucose to further breakdown. PFK is regulated by various factors to maintain the cellular energy balance.

3. Inhibition of PFK by Excess ATP

Excess ATP acts as an allosteric inhibitor of PFK. Allosteric regulation involves the binding of a regulatory molecule to a site other than the active site of the enzyme, resulting in a change in enzyme activity.

3.1 Allosteric Inhibition Mechanism

When ATP levels are high, ATP molecules bind to specific regulatory sites on PFK, causing a conformational change in the enzyme. This conformational change reduces the catalytic activity of PFK, inhibiting the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate.

3.2 ATP as a Negative Feedback Regulator

The inhibition of PFK by ATP is a negative feedback mechanism. When ATP levels are high, it indicates that the cell has sufficient energy and does not require more ATP production. Therefore, the inhibition of PFK by ATP helps regulate the rate of glycolysis and prevents excessive ATP production.

4. Importance of ATP Inhibition of PFK

The inhibition of PFK by excess ATP helps maintain energy balance and prevent the wasteful production of ATP. If PFK were not inhibited by excess ATP, glycolysis would continue at a high rate, leading to an excessive accumulation of ATP. This would be energetically unfavorable and could disrupt cellular homeostasis.

5. Significance in Cellular Metabolism

ATP inhibition of PFK also allows for the regulation of alternative metabolic pathways. When ATP levels are high and PFK activity is inhibited, glucose can be directed towards other pathways, such as glycogen synthesis or the pentose phosphate pathway, to meet the specific metabolic needs of the cell.

In conclusion, excess ATP inhibits the enzyme Phosphofructokinase (PFK) through allosteric regulation. This inhibition helps maintain energy balance, prevents excessive ATP production, and allows for the regulation of alternative metabolic pathways.

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