<p> Sulphate-reducing bacteria possess many redox proteins including some flavoproteins. Flavodoxins are a group of proteins with a tightly bound flavin mononucleotide (FMN) that mediate electron transfer at low redox potential.A novel FMN-binding protein from Desulphovibrio vulgaris has been cloned and crystallised and shown to be composed of 122 amino acids making it the smallest of the known proteins which bind FMN [<cite idref="PUB00011837"/>]. The exact function of this protein is unknown but it may take part in the electron-transfer pathway. The structure has been shown to contain a FMN-binding split barrel, which is related to the ferredoxin reductase-like FAD-binding domain. </p>