Glycolysis Flashcards
PFK
Irreversible rate limiting step of glycolysis
PFK 1 regulation
1) Energy control - AMP and ATP/Citrate
AMP - directly activates PFK
ATP/citrate - directly inhibits PFK
2) Glucose control - insulin and glucagon
Insulin - activate PFK1 indirectly by activating PFK2 –> Fructose-2,6-BP –> which then activate PFK1, overriding the ATP inhibition
Glucagon has the opposite effect, deactivate PFK2 so it won’t make the fructose-2,6-BP that will activate PFK2
Pyruvate kinase
Irreversible step, PEP to pyruvate
Substrate level phosphorylation, ATP output
What molecule increases the activation of pyruvate kinase?
F-1,6-BP
G3P dehydrogenase
Take out the H from G3P to make NADH
Create a very high energy intermediate
DHAP
Critical to triacylglyceride synthesis in hepatic and adipose tissues
It isomerizes G3P to glycerol
1,3-BPG and PEP
Precursor, “intermediates”, to ATP synthesis via substrate level phosphorylation
2,3-BPG
Ensures that oxygen is released to the tissues from Hb, taken off the blood cell
Reduce affinity to Hb, shift to the right (Bohr shift)
2,3-BPG effect on the lungs
No effect because saturation point was already reached (oxygen saturation is already 100% at the lungs)
Effect of 2,3-BPG on the fetal hemoglobin
Doesn’t bind well to fetal Hb so oxygen has increased affinity to hemoglobin (stays put on RBC), oxygen doesn’t get released to the tissues as much
3-phosphoglycerate kinase
Substrate level phosphorylation, ATP output
Hexokinase vs. glucokinase
Which has a lower Km?
Where is it found?
Hexokinase is inhibited by?
What is glucokinase induced by?
Hexokinase has lower Km while glucokinase’s Km is relative to the glucose concentration
Hexokinase found in most tissues while glucokinase is found in pancreatic and liver cells
Hexokinase is inhibited by it’s own product G6P.
Glucokinase is induced by insulin
