Table 4.
Metalloproteins in the respiratory electron transport chain in heterocysts.
| Family | Complex | Protein | Cofactor(s) | Metal † |
|---|---|---|---|---|
| NAD(P)H dehydrogenases | Type-1 NADP(H) dehydrogenase NDH-1 | NdhI | 2 × [4Fe–4S] clusters N6a, N6b | 8 Fe |
| NdhK | [4Fe–4S] cluster N2 | 4 Fe | ||
| Heme-copper oxidases |
aa3-type cytochrome c oxidase Cox2 |
CoxA2 | Cu center CuB | 1 Cu |
| Heme a3 | 2 Fe | |||
| Heme a | ||||
| CoxB2 | Cu–Cu center CuA | 2 Cu | ||
|
bo3-type quinol oxidase Qox (ARTO; Cox3) |
QoxA (CoxA3 §) |
Cu center CuB | 1 Cu | |
| Heme o3 | 2 Fe | |||
| Heme b | ||||
| Quinol oxidases | Cytochrome bd quinol oxidase |
CydA (All4024 §) |
Heme b595 | 3 Fe |
| Heme d | ||||
| Heme b558 | ||||
| Alternative oxidases | Plastoquinol terminal oxidase |
PTOX ‡ (All2096 §) |
Non-heme Fe–Fe center | 2 Fe |
† Charge is not given for transition metals as it varies with the oxidation state during electron transfer. ‡ The presence of PTOX in heterocysts has to be confirmed experimentally. § Specific examples in the strain Anabaena sp. PCC 7120.