Question

Phosphofructokinase, a rate-limiting enzyme of glycolysis, is inhibited when ATP is abundant. Why is this inhibition important?

1: Facilitates gluconeogenesis to maintain euglycemia
2: Allows the cell to divert glucose to be stored as glycogen
3: Promotes catabolism
4: Enhances the Tricarboxylic Acid (TCA) Cycle

Answer 1

Phosphofructokinase, a key enzyme in glycolysis, is inhibited by high levels of ATP, citrate, or a lower pH. This inhibition is important because it helps regulate the flow of glucose metabolism in the cell.

Step-by-step explanation:

Phosphofructokinase is the main enzyme controlled in glycolysis. High levels of ATP, citrate, or a lower, more acidic pH decrease the enzyme's activity.

An increase in citrate concentration can occur because of a blockage in the citric acid cycle. Fermentation, with its production of organic acids such as lactic acid, frequently accounts for the increased acidity in a cell; however, the products of fermentation do not typically accumulate in cells.