CHEM 3050 Lecture Notes - Lecture 2: Dihydroxyacetone Phosphate, Schiff Base, Enol
2 May 2018
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CHEM 3050
Lecture 2
The net result.. a switch in the Anomeric Carbon from C1 to C2; The ene-
diol rearrangement is normally base catalyzed in water, but It goes faster in
enzyme ΔG° = 1.7 kJ/mol
Now it’s on the verge (kinda) committed
Step 3: Phosphofructokinase-1 (PFK-1)
Phosphorylation of phosphofructose-1
This is the first (or second) irreversible step in glycolysis tightly
regulated; it is allosterically controlled by citrate, glucose-1,6-bisphosphate
and ATP (two active sites); increased glucagon levels (high energy)
decreases PFK-1 expression
The isomerization is ΔG° around 0, so it can go fairly readily, therefore this
is the first committed step (ΔG°= -14.2 kJ/mol) Isomerization prevents the
glucose from leaving; Mg dependent phosphorylation
Allosterically activated by AMP (low energy)
Step 4: Aldolase
Breaks the ring ΔG’° = βγ.8 kJ/mol works through a complex multistep
mechanism involving two Schiff bases; only works when there is a carbonyl
group on C2 & an hydroxyl group on C4 necessary for the Schiff base
mechanism of action (it’s a lyase)
Makes Dihydroxyacetone phosphate (DHAP) & Glyceraldehyde-3-
phosphate (GAP)
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