Enolase: Step 8 of Glycolysis

Question 1

What reaction does enolase catalyze?

Answer 1

Dehydration of 2-phosphoglycerate (2PG) to phosphoenolpyruvate (PEP)

Question 2

Which step in glycolysis creates a high energy phosphate?

Answer 2

The reaction of 2PG to PEP (phosphoenolpyruvate)

Question 3

Why is phosphoenolpyruvate a high energy phosphate molecule (i.e., why does it have high phosphoryl-transfer potential)?

Answer 3

The phosphate group traps the molecule in the enol (unstable) form. When the phosphate group is donated to ATP, the enol is able to convert to its more stable ketone form: pyruvate.

Question 4

What inhibits enolase?

Answer 4

Flouride (F-)

Question 5

Why does F- inhibit enolase?

Answer 5

In the presence of Pi, F- forms a complex with Mg2+ at the enzyme’s active site, blocking the substrate from binding.

Question 6

What substrate binds with enolase to produce phosphoenolpyruvate?

Answer 6

2-Phosphoglycerate (2PG)