Metabolic pathways

Question 1

Where does it occur: Cytoplasm

Regulatory enzyme: PFK-1

Do it’s enzymes need hydrophobic N-terminal tag? No because they are staying in the cytoplasm

Enzymes: Hexokinase/Glucokinase, phosphoglucoisomerase,PFK-1, Aldolase A, Triosephosphate isomerase, GAP dehydrogenase, phosphoglycerate kinase, phosphoglycerate mutase, enolase, and pyruvate kinase

Key enzymes: Hexokinase, PFK-1, and pyruvate kinase

Clinical correlations:

Hexokinase deficiency

PFK-1 deficiency

Pyruvate kinase deficiency

What is the pathway?

Answer 1

Glycolysis

Question 2

Cause: defective hexokinase (HK) gene

Enzyme affected: Hexokinase, specifically the HK1 isozyme. Hexokinase catalyzes conversion of glucose to gluc-6-P (G6P).

Presentation: Hemolytic anemia b/c erythrocytes can only generate ATP using glycolysis, and it needs ATP to power the NA+/K+ ATPase that helps maintain concentration gradients of the erythrocyte. No ATP means the ATPase no longer functions and the erythrocyte can no longer maintain its osmotic balance so fluid flows into it and it lyses. Fruc 2,6 BP deficiency b/c can’t make it since HK is defective. Fruc 2,6 BP faciliates tissue oxygenation by stabilizing the taut state of hemoglobin.

Treatment: blood transfusions and in some cases splenectomy

What is the disorder?

Answer 2

Hexokinase (HK) deficiency