Threonine and Methionine Catabolism to Succinyl CoA

The video explores the catabolism of methionine and threonine, detailing the enzymatic pathways involved. Methionine catabolism begins with methionine adenosyl transferase, leading to the production of homocysteine and further conversion to alpha-ketoglutarate. Threonine catabolism involves threonine dehydratase, producing alpha-keto butyrate. Both pathways converge at succinyl CoA, which plays a crucial 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?

• Degradation of isoleucine and valine

• Enzyme kinetics

• Degradation of methionine and threonine

• Synthesis of amino acids

Which enzyme initiates the methionine catabolic pathway?

• Methionine adenosyl transferase

• Cystathionine beta synthase

• Alpha-ketoacid dehydrogenase

• Threonine dehydratase

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

• Alpha-ketoglutarate

• Cysteine

• SAM

• Homocysteine

Which enzyme converts homocysteine to cystathionine?

• Methionine adenosyl transferase

• Threonine dehydratase

• Cystathionine gamma lyase

• Cystathionine beta synthase

What is the role of threonine dehydratase in threonine catabolism?

• Converts threonine to cysteine

• Converts threonine to SAM

• Converts threonine to alpha-keto butyrate

• Converts threonine to succinyl CoA

Which product is common to both methionine and threonine catabolism?

• Cysteine

• SAM

• Alpha-ketoglutarate

• Succinyl CoA

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

• It is used in fatty acid synthesis

• It is a starting material for ketone body synthesis

• It is a byproduct of glycolysis

• It is a glucogenic product

Which amino acid is both glucogenic and ketogenic?

• Threonine

• Valine

• Methionine

• Isoleucine

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

• To store amino acids

• To produce ketone bodies and glucose

• To synthesize proteins

• To produce amino acids

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

• Propionyl CoA carboxylase

• Methionine adenosyl transferase

• Cystathionine beta synthase

• Threonine dehydratase