Question

Pyruvate kinase catalyzes the last reaction in the glycolytic pathway:

phosphoenolpyruvate (PEP) + ADP --> pyruvate + ATP

There are four different mammalian forms of pyruvate kinase. All catalyze the same reaction, but they differ in their response to the glycolytic metabolite fructose-1,6-bisphosphate (F16BP).

The activity of two forms of pyruvate kinase was measured at various concentrations of PEP, as shown below. Activity was measured in the presence (blue circles) and absence (red circles) of F16BP.

Pyruvate Kinase Form 1 and Form 2 activity in the presence (blue circles) and absence (red circles) of F16BP.

How does F16BP affect pyruvate kinase?

Multiple answers:You can select more than one option

A

F16BP is an inhibitor of Form 1.

B

F16BP is an inhibitor of Form 2.

C

F16BP is an activator of Form 1.

D

F16BP is an activator of Form 2.

E

F16P has no effect on Form 1.

F

F16P has no effect on Form 2.

Answer 1

The right options are D and E.Explanation:

The graph shows shoes that there is in no change in activity of PK form 1 in absence of F16BP whereas activity of PK form 2 is deceased in absence of F16P (the red line is at lower levels).This implies that F16BP has no effect on PK form 1 whereas it an activator for PK form 2.

Option A is wrong because F16BP is not an inhibitor of Form 1, it has no effect on Form 1.

Option A is wrong because F16BP is not an inhibitor of Form 2.. it is an activator of Form 2.

Option A is wrong because F16BP is not an activator of Form 1, it has no effect on Form 1.

Option D and E are correct.

Option F is wrong because F16BP has effect on form 2.