Metabolism 2

Question 1

irreversible enzymes of gluconeogenesis and rxns

Answer 1

P-way Provides Fresh Glucose.
Pyruvate carboxylase (pyruvate ->OAA)
PEP carboxykinase (OAA -> PEP)
F1,6Pase (F1,6P ->F6P)
Glucose-6-phophatase

Question 2

Which enzyme of gluconeogenesis is deficient in von Gierke’s? Briefly describe the disease and mgmt.

Answer 2

Glucose-6-phosphatase.
Glycogen storage disease type I. Hepatomegaly. Enlarged kidneys. Requires frequent feedings w/ cornstarch to avoid hypoglycemia.

Question 3

What 5 factors does pyruvate d.h. require to function? What other enzyme resembles it?

Answer 3

1. Pyrophosphate (B1, TPP)
2. FAD (B2)
3. NAD (B3)
4. CoA (B5)
5. lipoic acid
   similar to α-ketoglutarate d.h.

Question 3

what toxin inhibits lipoic acid? what enzyme of glucose metabolism does this, in turn, inhibit?

Answer 3

arsenic inhibits lipoic acid, thereby inhibiting pyruvate d.h.

Question 4

Sx of arsenic poisoning

Answer 4

vomiting, rice water stools, garlic breath

Question 4

what toxin inhibits lipoic acid? what enzyme of glucose metabolism does this, in turn, inhibit?

Answer 4

arsenic inhibits lipoic acid, thereby inhibiting pyruvate d.h.

Question 5

Sx of arsenic poisoning

Answer 5

vomiting, rice water stools, garlic breath

Question 6

name the glycogen storage diseases and the affected enzymes in each

Answer 6

“Very Poor Carbohydrate Metabolism”
I. von Geirke’s - G6Pase
II. Pompe’s - lysosomal α-1,4-glucosidase
III. Cori’s - debranching enzyme
IV. McArdle’s - skeletal m. glycogen phosphorylase