Succinyl-coA synthetaste (SCS)

Question 1

first step rxn type

Answer 1

this is NAS

Question 2

second step rxn type

Answer 2

SN2 like

Question 3

third step rxn type

Answer 3

SN2

Question 4

diff of synthase and synthetase

Answer 4

synthase: did not use a nucleoTide
syntheTase: using a nucleoTide

Question 5

What is the point of this rxn?

Answer 5

• 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

Question 6

SCS structure

Answer 6

• alpha/beta heterodimer.
• beta subunit is the one who says “will i involve adenosine or guanine?”

Question 7

alpha subunit

Answer 7

includes a rossman fold

Question 8

rossman fold

Answer 8

bind nucleotides or their derivs… in this case will bind CoA!

Question 9

in mitochondria….

Answer 9

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)

Question 10

high energy intermds of SCS

Answer 10

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.

Question 11

stock up to this point

Answer 11

2 CO2, 2NADH, 1A/GTP from 1 acetyl-CoA equiv.

This is an acetyl-CoA from A PRIOR turn.