Methionine, Threonine Catabolism to Succinyl-S-CoA

The video tutorial explores the catabolism of methionine and threonine, focusing on their degradation pathways. Methionine catabolism involves enzymes like methionine adenosyl transferase and cystathionine beta synthase, leading to the production of alpha-ketobutyrate. Threonine catabolism involves threonine dehydratase, producing alpha-ketobutyrate as well. The conversion of propionyl CoA to succinyl CoA is detailed, highlighting its role in the TCA cycle and gluconeogenesis. Methionine is glucogenic, while threonine is both ketogenic and glucogenic.

What is the primary focus of the video?

• Introduction to protein synthesis

• Catabolism of all amino acids

• Synthesis of isoleucine and valine

• Degradation of methionine and threonine

Which enzyme initiates the methionine catabolic pathway?

• Cystathionine beta synthase

• Methionine synthase

• Threonine dehydratase

• Methionine adenosyl transferase

What is the product of the reaction catalyzed by methionine adenosyl transferase?

• SAM

• Homocysteine

• SAH

• Cysteine

Which enzyme converts homocysteine to cystathionine?

• Cystathionine beta synthase

• Methionine adenosyl transferase

• Threonine dehydratase

• Cystathionine gamma lyase

What is the role of threonine dehydratase in threonine catabolism?

• Converts threonine to alpha-ketobutyrate

• Converts threonine to SAM

• Converts threonine to cystathionine

• Converts threonine to acetyl CoA

Which product is common to both methionine and threonine catabolism?

• SAM

• Acetyl CoA

• Cysteine

• Alpha-ketobutyrate

What is the significance of succinyl CoA in the TCA cycle?

• It is an essential amino acid

• It is a ketogenic product

• It is a byproduct of protein synthesis

• It is a glucogenic product

Which amino acid is both glucogenic and ketogenic?

• Threonine

• Isoleucine

• Methionine

• Valine

What is the primary function of the liver in amino acid catabolism?

• Produce ketone bodies and glucose

• Synthesize proteins

• Store amino acids

• Convert amino acids to fats

Which enzyme is involved in the conversion of propionyl CoA to succinyl CoA?

• Cystathionine beta synthase

• Methionine adenosyl transferase

• Threonine dehydratase

• Methylmalonyl CoA mutase