Aromatic amino acid metabolism — Flashcards

Flashcard 1: Which metabolic disorder is associated with bluish-black connective tissue and sclerae (ochronosis)? _____

Answer: Alkaptonuria

Flashcard 2: Albinism is usually due to decreased _____ activity or defective tyrosine transport

Answer: tyrosinase

Flashcard 3: Pyruvate dehydrogenase deficiency is characterized by _____ serum alanine starting at infancy

Answer: increased

Flashcard 4: Which amino acid is the precursor to serotonin and niacin? _____

Answer: Tryptophan

Flashcard 5: What amino acid becomes essential in patients with phenylketonuria? _____

Answer: Tyrosine

Flashcard 6: What vitamin deficiency may be caused by malignant carcinoid syndrome? _____

Answer: Niacin (B3) deficiency

Flashcard 7: What stainable protein is abundant in astrocytes?

Answer: GFAP

Flashcard 8: What enzyme converts pyruvate to alanine?

Answer: alanine aminotransferase (ALT)

Flashcard 9: Role of myeloperoxidase in neutrophils:

Answer: Plays a role in respiratory burst (catalyzes formation of HOCl from H2O2)

Extra: Myeloperoxidase (MPO) is found in the azurophilic granules of neutrophils (PMNs). During the respiratory burst, it converts Hydrogen Peroxide (H2O2) and Chloride ions into Hypochlorous acid (HOCl - bleach), which is a potent bactericidal agent.

Flashcard 10: What reaction is catalyzed by superoxide dismutase during the respiratory burst?

Answer: Conversion of Superoxide ($O_2^-$) to Hydrogen peroxide ($H_2O_2$)

Extra: Superoxide dismutase (SOD) neutralizes superoxide radicals. Reaction: 2O2- + 2H+ -> H2O2 + O2. Clinical Pearl: Mutations in superoxide dismutase 1 (SOD1) are associated with Amyotrophic Lateral Sclerosis (ALS).