Table 2. Categories of O2-dependent enzymes.
| Category | Subcategory by catalytic center | Metal species at catalytic center | Ligands for the metal species at catalytic center (cofactor/substrate and enzyme residues) | Number of enzymes |
|---|---|---|---|---|
| Dioxygenase | 2-OG-dependent dioxygenase | Fe | 2-OG, His, His, Asp/Glu | 59 |
| Heme-dependent dioxygenase | Fe | Heme, His | 5 | |
| Lipoxygenase | Fe | His, His, His, Ile, His/Asa/Asn/none | 6 | |
| Others | Fe | His, His, His/Asp/Glu* | 10 | |
| Monooxygenase | Heme-dependent monooxygenase | Fe | Heme, Cys/His/Glu | 61 |
| Non-Heme Fe-dependent monooxygenase | Fe | His, His, His/Asp/Glu* | 9 | |
| Cu-dependent monooxygenase | Cu | His, His, Met | 5 | |
| Flavin-dependent monooxygenase | None (uses flavin) | N/A | 12 | |
| Others† | N/A | N/A | 2 | |
| Oxidase | Heme-copper | Fe and Cu | His, His, His for Cu; Heme and His for Fe | 1 |
| Fe-dependent oxidase | Fe | Varies | 14 | |
| Cu-dependent oxidase | Cu | Varies | 7 | |
| Flavin-dependent oxidase | None (uses flavin) | N/A | 25 | |
| Others† | N/A | N/A | 5 |
*
Substrates/cofactor ligands for this category varies for each member depending on the reaction it catalyzes.
†
Members in this category are not fully studied.