Leucine Deamination and Oxidation

The video tutorial explains the catabolic pathway of leucine, highlighting its differences from valine catabolism. It details the enzymatic reactions involved, including the role of transaminase and dehydrogenase enzymes. The tutorial discusses the energy yield from leucine catabolism, emphasizing the formation of a proton gradient and the production of NADH. It also covers the biochemical pathways leading to the formation of acetyl CoA and acetoacetate, concluding with a summary and yield calculation of the entire process.

What is the primary difference between leucine and valine catabolism?

• Leucine catabolism ends with propionyl-CoA.

• Valine catabolism does not involve any enzymes.

• Leucine catabolism involves HMG-CoA.

• Valine catabolism produces acetyl-CoA.

Which enzyme is NOT involved in the initial steps of leucine catabolism?

• Pyruvate dehydrogenase

• Branched-chain alpha-ketoacid dehydrogenase complex

• Alpha-ketoglutarate dehydrogenase

• Branched-chain transaminase

What is the role of electron transferring flavoprotein in leucine catabolism?

• It carboxylates leucine.

• It transfers electrons to Coenzyme Q.

• It reduces FAD to FADH2.

• It oxidizes NADH.

Which molecule is formed after the carboxylation of 3-methylcrotonyl-CoA?

• Hydroxymethylglutaryl-CoA

• Succinyl-CoA

• Acetyl-CoA

• Propionyl-CoA

What is the significance of HMG-CoA in leucine catabolism?

• It is a waste product.

• It is used in fatty acid synthesis.

• It is converted directly to glucose.

• It is a precursor for ketone bodies.

How many NADH molecules are produced from the complete catabolism of leucine?

• 15

• 11

• 7

• 5

What is the net ATP yield from leucine catabolism?

• 1 ATP

• 4 ATP

• 2 ATP

• 3 ATP

Which enzyme splits acetoacetyl-CoA into two acetyl-CoA molecules?

• Hydratase

• Thiolase

• Carboxylase

• Dehydrogenase

What is the role of succinyl-CoA in the conversion of acetoacetate?

• It is oxidized to malate.

• It acts as a coenzyme A donor.

• It is converted to fumarate.

• It is reduced to succinate.

Which condition favors the catabolism of leucine over anabolic processes?

• Low protein intake

• High blood sugar

• High glucagon levels

• High insulin levels