Enzyme 

Reaction 

Co-factor or Prosthetic group 

Importance

1. Tyrosinase

Hydroxylation of tyrosine to dihydroxy compound followed by oxidation and polymerization to melanin pigments

Copper

Pigmentation

Lack of it or masking leads to leukoderma

2. Phenylalanine

hydroxylase

Phenylatane -->

Tetrahydropterine

Lack of it leads to

phenylketonuria

3. Tyrosine hydroxylase

Tyrosine --> DOPA

Tetrahydropterine

Formation of noradrenaline in adrenals and brain

4. Tryptophan

hydroxylase

Tryptophan --> 5 hydroxytryptophan

Tetrahydropterine

Rate-limiting oxygen dependent step in the biosynthesis of serotonin detoxication.