Post on 22-Dec-2015
PFK-1 commits hexoses to glycolysis
The glycolysis product glucose-6-phosphate can be used for both glycolysis and glycogen formation.
Phosphorylation of Fructose-6 phosphate is an irreversible step that expends cellular ATP and commits hexoses to glycolysis. The enzyme PFK-1 must be regulated to ensure optimal resource usage.
PFK-1 regulation
• PFK-1 is ATP dependent and its activity is increased by ATP availability.
• At higher levels of ATP, the ATP binds to allosteric regulation sites reducing the activity.
• ADB also binds to allosteric regulation sites activating PFK-1. – The balance between ATP and ADP in the cell is indicative of
energy usage and is the regulator system for PFK-1
• Bound ATP rotates the positions of Arg162 and Glu161
• the positive charge on Arg162 stabilizes the negative charge on the phosphate of F6P, and Km is low
• The negative charge on Glu161 repulses the F6P and raises the Km