PKU—phenylketonuria,
HT-2—tyrosinemia type II,
HT-3—tyrosinemia type III,
AKU—alkaptonuria,
HT-1—tyrosinemia type I.

Substrates/products:
Phe—phenylalanine,
Tyr—tyrosine,
pHPP—p-hydroxyphenylpyruvate,
hga—homogentisate,
maa—maleylacetoacetate,
faa—fumarylacetoacetate.

Enzymes:
PAH—phenylalanine hydroxylase,
TAT—tyrosine transaminase,
HPD—4-hydroxyphenylpyruvate dioxygenase,
HGD—homogentisate oxidase,
MAAI—maleylacetoacetate isomerase,
FAH—fumarylacetoacetase.

Cofactors:
O
2—molecular oxygen,
4a-OH-BH
4—4a-hydroxytetrahydrobiopterin,
H
2O—water,
q-BH
2—7,8-dihydrobiopterin,
NADH/NAD+
—nicotinamide adenine dinucleotide,
BH
4—tetrahydrobiopterin,
α-KG—alpha-ketoglutarate,
Glu—glutamate,
CO
2—carbon dioxide,