Cysteine Catabolism to Pyruvate

What is the primary role of cysteine dioxygenase in cysteine metabolism?

• To convert cysteine into taurine

• To regulate the synthesis of bile acids

• To synthesize cysteine from pyruvate

• To remove cysteine from the blood and convert it to sulfinoalanine

What happens to cysteine dioxygenase when cysteine levels fall in the blood?

• It becomes more active

• It is phosphorylated

• It is ubiquitinated and degraded

• It converts cysteine to taurine

Which enzyme is responsible for the transamination of sulfinoalanine?

• Cysteine dioxygenase

• Pyruvate kinase

• Sulfinoalanine transaminase

• Sulfite oxidase

What is the fate of pyruvate produced in liver cells from cysteine catabolism?

• It is excreted as waste

• It is used in fatty acid synthesis

• It enters gluconeogenesis to form glucose

• It is converted to lactate

How does sulfite oxidase modify sulfite in the cysteine degradation pathway?

• It reduces sulfite to hydrogen sulfide

• It converts sulfite to sulfate by incorporating oxygen

• It converts sulfite to sulfur dioxide

• It removes oxygen from sulfite

Why is sulfinoalanine transaminase considered the same as aspartate transaminase?

• They have identical amino acid sequences

• They catalyze the same reaction with different substrates

• They are both involved in taurine biosynthesis

• They are both mitochondrial enzymes

What structural similarity does sulfinoalanine share with aspartate?

• Both have a carboxyl group in place of a sulfino group

• Both have a sulfino group

• Both lack an alpha carbon

• Both are aromatic amino acids