How many ATP or equivalents would be generated from theSucci

How many ATP or equivalents would be generated from theSuccinyl-CoA step after the equivalent of all its four carbons (don’t worry about position) were converted to CO2? State your assumptions, e.g. ample AcCoA is present. We believe the answer is 20 ATP equivalents but are unsure of the reasoning.

Solution

Considering the fact that:
1 NADH,H+ yields 3 ATPs in the respiratory chain and
1 FADH2 yields 2 ATP,

from the Succinyl-CoA step, the ATP yield would be:

(1) Succinyl CoA converted to Malate = 3 GTP
(2) Malate up to Pyruvate (1 NADPH,H+) = gives 3 ATP
(3) Pyruvate up to Acetyl Co A = 3 ATP
(4) When Acetyl CoA undergoes oxidation in the Krebs Cycle = 12 ATP

21 ATP equivalents would be generated from the Succinyl-CoA step after the equivalent of all its four carbons.