BIOC 212 Lecture Notes - Lecture 44: Insulin, Phosphofructokinase 2, Phosphoglycerate Kinase
29 May 2018
School
Department
Course
Professor
Metabolism VI
Energy Output
• ATP input in steps 1 & 3
o Activate each end of sugar
o Put in two molecules of ATP; phosphorylate glucose & fructose
• Each molecule of glyceraldehyde-3-P creates 1 NADH and 2 ATPs
• NADH output in step 6
o Add P to aldehyde
• ATP output step 7 & 10
• Input of 2 ATP and output of 4 ATP and 2 NADH
o Doubled ATP that started with
o Net output of 2 ATP & 2 NADH
Step 3 PFK Regulates Glycolysis
• Enzymes allow you to regulate the pathway; speeding it up or slowing it down
when needed
• Main regulation at step 3; do not need to control all steps
o Fructose-6-P + ATP → fructose-1,6-bP + ADP
• Enzyme PFK can bind ATP in two different ways
o One binding site to phosphorylate fructose, and one to regulate the activity
of the enzyme
• PFK binds ATP at catalytic site and another regulatory site (allosteric
regulation)
o ATP binding at regulatory site inhibits the catalytic site
• If have lots of ATP around, do not need more ATP so stop the reaction
o Store glucose as glycogen until ATP needed
• All these things are also generating heat; do not want to keep
producing ATP if not needed (T homeostasis)
• AMP competes for ATP and prevents inhibition
o AMP also binds to the regulatory site; compete for binding with ATP
o Does not inhibit the enzyme, rather prevents ATP from inhibiting
o When have low ATP levels in cell, have more AMP which allows reaction to
continue
o AMP is less common than ADP since constant conversion of ATP --> ADP
• Have lots of AMP when really deplete energy
• ATP:AMP ratio signals need for glycolysis
o Ratio is being sensed as a signal for how much energy the cell needs
