Rate-determining enzymes of metabolic processes

Question 1

Glycolysis

Answer 1

ENZYME
Phosphofructokinase-1 (PFK-1)

REGULATORS
AMP⊕, fructose-2,6-bisphosphate⊕

ATP⊝, citrate⊝

Question 2

Gluconeogenesis

Answer 2

ENZYME
Fructose-1,6-bisphosphatase

REGULATORS
AMP ⊝, fructose-2,6-bisphosphate ⊝

Question 3

TCA cycle

Answer 3

ENZYME
Isocitrate dehydrogenase

REGULATORS
ADP ⊕

ATP ⊝, NADH ⊝

Question 4

Glycogenesis

Answer 4

ENZYME
Glycogen synthase

REGULATORS
Glucose-6-phosphate ⊕, insulin ⊕, cortisol ⊕

Epinephrine ⊝, glucagon ⊝

Question 5

Glycogenolysis

Answer 5

ENZYME
Glycogen phosphorylase

REGULATORS
Epinephrine ⊕, glucagon ⊕, AMP ⊕

Glucose-6-phosphate ⊝, insulin ⊝, ATP ⊝

Question 6

HMP shunt

Answer 6

ENZYME
Glucose-6-phosphate dehydrogenase (G6PD)

REGULATORS
NADP+ ⊕

NADPH ⊝

Question 7

De novo pyrimidine synthesis

Answer 7

ENZYME
Carbamoyl phosphate synthetase II

REGULATORS
ATP ⊕, PRPP ⊕

UTP ⊝

Question 8

De novo purine synthesis

Answer 8

ENZYME
Glutamine-phosphoribosylpyrophosphate
(PRPP) amidotransferase

REGULATORS
AMP ⊝, inosine monophosphate (IMP) ⊝, GMP ⊝

Question 9

Urea cycle

Answer 9

ENZYME
Carbamoyl phosphate synthetase I

REGULATORS
N-acetylglutamate ⊕

Question 10

Fatty acid synthesis

Answer 10

ENZYME
Acetyl-CoA carboxylase (ACC)

REGULATORS
Insulin ⊕, citrate ⊕

Glucagon ⊝, palmitoyl-CoA ⊝

Question 11

Fatty acid oxidation

Answer 11

ENZYME
Carnitine acyltransferase I

REGULATORS
Malonyl-CoA ⊝

Question 12

Ketogenesis

Answer 12

ENZYME

HMG-CoA synthase

Question 13

Cholesterol synthesis

Answer 13

ENZYME
HMG-CoA reductase

REGULATORS
Insulin ⊕, thyroxine ⊕

Glucagon ⊝, cholesterol ⊝