ABSTRACT
Nitrite + 6 reduced ferredoxin + 7H+ = NH3 + 2H2O + 6 oxidised ferredoxin.
Reduced ferredoxin
Oxidized ferredoxin
4.2. Siroheme Siroheme is synthesized by the tetrapyrrole pathway, begins with the synthesis of 5-aminolevulinate (ALA) either by the condensation of the succinyl CoA and glycine, as in animals, yeast, and the a-group of the proteobacteria or by the transformation of glutamate, as in higher and lower plants and most other bacteria. Eight molecules of ALA are converted into Uroporphyrinogen III by the concerted action of three enzymes, namely ALA-dehydrotase, porphobiligen deaminase, and Urogen III synthase, Urogen III serves as the central template from which all biologically functional modified tetrapyrroles are derived by a number of enzyme-mediated modifications that include peripheral alterations to the acetate and propionate side chains, methylations, oxidation state of the macrocycle, ring size and the central metal ion.
