Rate-Determining Enzymes of Metabolism

Question 1

Glycolysis

Answer 1

Phosphofructokinase-1 (PFK-1)
AMP +, fructose-2,6-bisphosphate +
ATP -, citrate -

Question 2

Gluconeogenesis

Answer 2

Fructose-1,6-bisphosphatase
ATP +, acetyl-CoA +
AMP -, fructose-2,6-bisphosphate -

Question 3

TCA cycle

Answer 3

Isocitrate dehydrogenase
ADP +
ATP -, NADH -

Question 4

Glycogenesis

Answer 4

Glycogen synthase
Glucose-6-phosphate +, insulin +, cortisol +
Epinephrine -, glucagon -

Question 5

Glycogenolysis

Answer 5

Glycogen phosphorylase
Epinephrine +, glucagon +, AMP +
Glucose-6-phosphate -, insulin -, ATP -

Question 6

HMP shunt

Answer 6

Glucose-6-phosphate dehydrogenase (G6PD)
NADP+ +
NAPDH -

Question 7

de novo pyrimidine synthesis

Answer 7

Carbamoyl phosphate synthetase II
ATP +
UTP -

Question 8

de novo purine synthesis

Answer 8

Glutamine-phosphoribosylpyrophosphate (PRPP) amidotransferase
AMP -, IMP -, GMP-

Question 9

Urea cycle

Answer 9

Carbamoyl phosphate synthetase I

N-acetylglutamate +

Question 10

Fatty acid synthesis

Answer 10

Acetyl-CoA carboxylase (ACC)
Insulin +, citrate +
Glucagon -, palmitoyl-CoA -

Question 11

Fatty acid oxidation

Answer 11

Carnitine acyltransferase I

Malonyl-CoA -

Question 12

Ketogenesis

Answer 12

HMG-CoA synthase

Question 13

Cholesterol synthesis

Answer 13

HMG-CoA reductase
Insulin +, thyroxine +
Glucagon -, cholesterol -