Rate-limiting Enzyme

Phosphofructokinase (PFK)

Glycolysis

Glucose-6-phosphate dehydrogenase (G6PD)

PPP (pentose phosphate pathway)

Pyruvate dehydrogenase (PDH)

Pyruvate oxidation

Isocitrate dehydrogenase (IDH)

TCA (Tricarboxylic acid) cycle/ Szent-Györgyi-Kreb’s cycle/ Citric acid cycle/

Complex IV (technically not an enzyme though)

Oxidative Phosphorylation [OxPhos] (ETC)

All enzymes reversing glycolysis

Gluconeogenesis

Glycogen synthase

Glycogenesis

Glycogen phosphorylase

Glycogenolysis

Acetyl-CoA reductase (ACC)

Fatty acid synthesis

HMG-CoA reductase

MVA pathway

DOXP reductoisomerase

MEP pathway

Carnitine palmitoyl-transferase (CPT1)

Beta oxidation

HMG-CoA synthase

Ketogenesis

Pyrimidines: Aspartate transcarbamolase (ATCase)

Purines: Amidophosphoribosyltransferase (ATase)

De novo (nucleotide)

Xanthine oxidase

Purine breakdown

Carbamoyl phosphate synthetase 1 (CPS I)

Urea Cycle

ALA (aminolevulinic acid) synthase

Porphyrin synthesis

No clear winner

Shikimate pathway