Exam 23: Protein Turnover and Amino Acid Catabolism

Describe the structure and function of the 26S proteasome.

Uricotelic organisms release nitrogen as

The C-terminal glycine of ubiquitin is covalently linked to ________________ residues of the protein destined to be degraded.

Biopterin is a complicated coenzyme required for the conversion of Phe to Tyr.Why is biopterin not considered a vitamin?

Surplus amino acids are

Which of the following is a product of the transamination of aspartate and $\alpha$ -ketoglutarate?

In the urea cycle,the second nitrogen of urea enters the cycle in the form of which of the following metabolites?

What product of the first step of methionine degradation is an important methyl group donor?

What is the structure of compound X in the following metabolic reaction? Name the type of reaction.

What class of enzymes cleaves most aromatic rings in biological systems?

Nitrogen is transported from muscle to liver in the form of ______________.

In the degradation of amino acids other than Thr or Ser,the amino nitrogens can eventually become the amino group of ___________________.

What protein is used as a tag to identify proteins that are targeted for destruction?

What term describes a specific sequence of amino acids that indicates the particular protein should be degraded?

Which amino acid is solely ketogenic?

Ubiquitin-tagged proteins are digested by the __________________.

What molecule is formed from excess ammonium ions by ureotelic organisms?

The hydrolysis of arginine by arginase produces ornithine and ______________.

Which amino acids supply carbons as succinyl CoA for eventual entry into metabolism?

Serine dehydratase catalyzes the conversion of serine into NH₄⁺ and __________________.