Glycolysis regulation

Question 1

1st step regulation

Answer 1

Glucose 6-Phosphate allosterically inhibits hexokinase I, II, and III. An example of feedback inhibition

Question 2

3rd step regulation

Answer 2

FIRST COMMITED STEP thus subject to regulation:

1) Inhibition
- ATP-is both a cosubstrate and an allosteric inhibitor
- Citrate- intermediate of the Kreb’s cycle inhibits PFK-1. An increase in the concentration of citrate indicates a blockage in the Kreb’s Cycle–>feedback inhibition
- H+-> increase in the concentration of H+ indicates an increase in lactic acid and an inability of pyruvate to enter Kreb’s cycle

Activation:

• AMP/ADP- an allosteric activator that relieves the inhibition caused by ATP
• Fructose 2,6-bisphosphate-> involved with glucagon and as the concentration of fructose 2,6-bisphosphate decreases- PFK-1 activity decreases and glycolysis is inhibited which leads to gluconeogenesis pathway

Question 3

10th step regulation

Answer 3

• Fructose 1,6-bisphosphate is an activator for the pyruvate kinase. Fructose 1,6 bisphosphate feeds forward in the reaction and activates the enzyme
• *FEED FORWARD INHIBITOR

ATP can also inhibit the enzyme pyruvate kinase