Disorders of glycolytic enzymes — Flashcards

Flashcard 1: Pyruvate kinase deficiency results in increased levels of _____, which causes decreased Hb affinity for O2

Answer: 2,3-BPG

Flashcard 2: What glycolysis enzyme deficiency causes hemolytic anemia in a newborn?_____

Answer: Pyruvate kinase deficiency

Flashcard 3: What is the only metabolic pathway for generating ATP, anaerobically? _____

Answer: Glycolysis

Flashcard 4: Pyruvate kinase is regulated via feed-forward activation by _____

Answer: fructose-1,6-bisphosphate

Flashcard 5: What is the rate-limiting enzyme of glycolysis?_____

Answer: Phosphofructokinase-1 (PFK-1)

Flashcard 6: What is the function of the bifunctional enzyme Phosphofructokinase-2/Fructose bisphosphatase-2 (PFK-2/FBP-2)?

Answer: A bifunctional enzyme that regulates the levels of Fructose-2,6-bisphosphate (F-2,6-BP), thereby balancing glycolysis and gluconeogenesis.

Extra: In the well-fed state, PFK-2 is active (increased F-2,6-BP) → stimulates Glycolysis.\nIn the fasting state, FBP-2 is active (decreased F-2,6-BP) → stimulates Gluconeogenesis.

Flashcard 7: Where does glycolysis take place?

Answer: cytoplasm

Flashcard 8: What is the rate-limiting enzyme of glycolysis?

Answer: Phosphofructokinase-1 (PFK-1)

Extra: The three irreversible steps of glycolysis are catalyzed by:\n1. Hexokinase/Glucokinase\n2. Phosphofructokinase-1 (Rate-limiting step)\n3. Pyruvate kinase\n\nPFK-1 is inhibited by ATP and Citrate, and activated by AMP and Fructose-2,6-bisphosphate.

Flashcard 9: What enzyme converts pyruvate to lactate?

Answer: lactate dehydrogenase (LDH)

Flashcard 10: Role and primary locations of Glucokinase

Answer: Catalyzes the first step of glycolysis and glycogen synthesis (Glucose → G6P) in the liver and pancreatic β-cells.

Extra: Traps glucose within the cell by phosphorylation. Induced by insulin. Compared to Hexokinase: High Km (lower affinity) and High Vmax (higher capacity).