Flavodoxin, long chain <p>Flavodoxins are small redox-active proteins with a flavin mononucleotide (FMN) prosthetic group. They function as electron transfer agents in a variety of microbial metabolic processes, including nitrogen fixation by nitrogenase [<cite idref="PUB00014920"/>], sulphite reduction [<cite idref="PUB00014352"/>], and light-dependent NADP+ reduction during photosynthesis [<cite idref="PUB00014921"/>]. This entry describes the long chain type, typical for nitrogen fixation but associated with pyruvate formate-lyase activation and cobalamin-dependent methionine synthase activity in <taxon tax_id="562">Escherichia coli</taxon> [<cite idref="PUB00014922"/>].</p>