Succinyl-coA synthetaste (SCS) Flashcards
first step rxn type
this is NAS
second step rxn type
SN2 like
third step rxn type
SN2
diff of synthase and synthetase
synthase: did not use a nucleoTide
syntheTase: using a nucleoTide
What is the point of this rxn?
- to exchange one high energy thioester bond for another (can be atp or gtp)
gtp- used in livery or kidney (anabolic tissue)… likely to be running in synthetic sense
atp - oxidative tissue, breaking things down
SCS structure
- alpha/beta heterodimer.
- beta subunit is the one who says “will i involve adenosine or guanine?”
alpha subunit
includes a rossman fold
rossman fold
bind nucleotides or their derivs… in this case will bind CoA!
in mitochondria….
have more GTP than GDP, and ATP/ADP are equivalent.
Why important?
anabolic have more reactant of succinyl-coA, catabolic have more succinate product.
What tells you about the TCA?
1. Tells us that directionality is tissue dependent… it says that the TCA is adaptive, bc it has the ability for to have directionality (change), can adapt it to any tissue that needs to be involved in that….
2. also tells us that the TCA is amphibolic (can do both cata and ana)
high energy intermds of SCS
save ∆G of hydrolysis…
in this sceneario we have a charged dipole interaction. This interaction will stabilize phospho histidine intermediate.
Charged dipole interaction: charge and dipole are offsetting each other.
Charge = - on the phosphate of his,
dipole = partial + from the power helices
The phospho his is stabilizes to keep a smooth intermediate without dropping down in energy.
stock up to this point
2 CO2, 2NADH, 1A/GTP from 1 acetyl-CoA equiv.
This is an acetyl-CoA from A PRIOR turn.