Exam 23: Protein Turnover and Amino Acid Catabolism

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

Why are four or more chains of ubiquitin particularly effective as a signal for degradation?

Which amino acids can be converted to pyruvate by a single enzyme-catalyzed reaction?

In the first step of the urea cycle, CO₂ and NH₄⁺ are converted into __________________.

What is the basic strategy by which amino acids are degraded?

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

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

Ubiquitin-tagged proteins are digested by the __________________.

The genetic deficiency of the enzyme __________________________ results in a condition referred to as maple syrup urine disease.