Oxygenation reactions are the ones in which the molecular oxygen atom is added to another molecule. In most cases, it can open up the ring e.g aromatic amino acids like PHE, TYR, TRP. Based on the fact that O2 has two atoms if both are used the process is called dioxygenation while using one of them is a monooxygenation reaction.
Monooxygenation
In monooxygenation, one atom of molecular oxygen forms the hydroxyl group of the substrate while the other forms water with the hydrogens of the cofactor.
The role of monooxygenation (hydroxylation) in amino acid metabolism:
- PHE degradation into TYR
- Neurotransmitter synthesis from TYR, TRP
There is an aromatic amino acid hydroxylase enzyme family: enzymes of this family use tetrahydrobiopterin (BH4), as a cofactor (Figure 1).
Important to note, that the BH4-BH2 circle can recover by the spontaneous way which is really slow or by the BH2 reductase using NADPH. In the non-classical PKU, this