Homocystinuria and methionine metabolism disorders — Flashcards

Flashcard 1: Vitamin B9 (folate) deficiency is characterized by _____ homocysteine levels

Answer: increased

Flashcard 2: Vitamin B9 (folate) deficiency is characterized by _____ methylmalonic acid levels

Answer: normal

Flashcard 3: Vitamin B12 and folate deficiency result in mildly elevated _____ levels, increasing risk for thrombosis

Answer: homocysteine

Flashcard 4: Which amino acids (2) have sulfur groups? _____

Answer: Cysteine, Methionine

Flashcard 5: Methyl-THF (reduced THF) is used by the enzyme _____ to convert homocysteine to methionine

Answer: methionine synthase

Flashcard 6: What stainable protein is abundant in astrocytes?

Answer: GFAP

Flashcard 7: What enzyme converts pyruvate to alanine?

Answer: alanine aminotransferase (ALT)

Flashcard 8: 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 9: 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).

Flashcard 10: The Golgi makes modifications to some amino acids trafficking through it. What are the modifications made to threonine?

Answer: O-oligosaccharide