Question

FAD is reduced in which of the reaction of the Kreb’s cycle?



Isocitrate to oxaloacetate





Succinate to fumarate





Fumarate to malate





Succinyl CoA to Succinate​

Answer 1

Succinate to fumarate in this reaction of krebs cycle the FAD is reduced to FADH2 by the succinate dehydrogenase enzyme.

Answer 2

FAD is reduced in Succinate to fumarate reaction of the Kreb’s cycle.

• There are 8 steps in Kerb's cycle and the process of conversion of succinate to fumarate occurs in the 6th step.

• In the 6th step, Succinate that is formed from Succinyl CoA is converted to fumarate by the action of an enzyme Succinate dehydrogenase. This enzyme is present in intramitochondrial space.

• In Kreb's cycle, this reaction is the only one in which dehydrogenation  occurs with the use of high energy molecule FAD+ without using NAD+

• FAD+ is converted to FADH₂