Glutaminase Catabolism of Glutamine

The video explains the mechanism of glutaminase, an enzyme that reverses the reaction of glutamine synthetase by converting glutamine back to glutamate. It details the steps involved in the enzyme's mechanism, including nucleophilic attack and hydrolysis, and highlights the enzyme's importance in energy production and the urea cycle. The video also discusses the role of glutaminase in the liver's mitochondria, where it helps catabolize glutamine for energy and facilitates ammonia excretion through the urea cycle.

What is the primary function of glutamine synthetase?

• To convert glutamine to glutamate

• To convert glutamate to glutamine

• To convert ammonia to urea

• To convert alpha-ketoglutarate to glutamate

Which type of enzyme is glutaminase classified as?

• Threonine hydrolase

• Cysteine hydrolase

• Lysine hydrolase

• Serine hydrolase

What is the role of the deprotonated cysteine in the glutaminase mechanism?

• It performs a nucleophilic attack

• It acts as a leaving group

• It binds to ammonia

• It stabilizes the enzyme structure

What happens to ammonia after it is released from the active site of glutaminase?

• It forms a thioester bond

• It is converted to urea immediately

• It undergoes proton exchange to form ammonium

• It binds to another enzyme

What is the final product of the glutaminase reaction?

• Glutamine

• Alpha-ketoglutarate

• Glutamate

• Urea

Where is glutaminase primarily found in the body?

• In the muscles

• In the brain

• In the liver

• In the kidneys

What is the fate of the ammonia produced by glutaminase in the liver?

• It is stored in the liver

• It is converted to urea in the urea cycle

• It is used in the synthesis of proteins

• It is excreted directly as ammonia