Rate-Determining Enzymes of Metabolic Pathways

Question 1

Glycolysis

Answer 1

Phosphofructokinase-1 (PFK-1)

+ Regulators: AMP, F-2,6-bisphosphate
- Regulators: ATP, citrate

Question 2

Gluconeogenesis

Answer 2

Fructose-1,6-bisphosphatase

+: ATP, acetyl-CoA
-: AMP, fructose-2,6-bisphosphatase

Question 3

TCA Cycle

Answer 3

Isocitrate dehydrogenase

+: ADP
-: ATP, NADH

Question 4

Glycogenesis

Answer 4

Glycogen synthase

+: G6P, insulin, cortisol
-: epinephrine, glucagon

Question 5

Glycogenolysis

Answer 5

Glycogen phosphorylase

+: epinephrine, glucagon, AMP
-: G6P, insulin, ATP

Question 6

HMP shunt

Answer 6

G6P dehydrogenase

+: NADP+
-: NADPH

Question 7

De novo pyrimidine synthesis

Answer 7

Carbamoyl phosphate synthetase II

Question 8

De novo purine synthesis

Answer 8

Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase

-: AMP, inosine monophosphate (IMP), GMP

Question 9

Urea cycle

Answer 9

Carbamoyl phosphate synthetase I

+: N-acetylglutamate

Question 10

Fatty acid synthesis

Answer 10

Acetyle-CoA carboxylase

+: insulin, citrate
-: glucagon, palmitoyl-CoA

Question 11

Fatty acid oxidation

Answer 11

Carnitine acyltransferase

-: Malonyl-CoA

Question 12

Ketogensis

Answer 12

HMG-CoA synthase

Question 13

Cholesterol synthesis

Answer 13

HMG-CoA reductase

+: insulin, thyroxine
-: glucagon, cholesterol