User:Aiccicco/Flavodoxin

Lead
Flavodoxins are soluble proteins used in many electron transfer reactions within both prokaryotes and eukaryotes. In cyanobacteria such as Anabaena and Nostoc sp., flavodoxins are heterocyst-specific, and used in photosystem 1 to deliver electrons to nitrogenase, as well as reducing N2 and NADP+, Nitrogen fixing and H2 formation

Article body
Flavodoxin is characterized by its FMN (flavin mono-nucleotide) (a Vitamin B2) in which the primary OH group has been converted to a dihydrogen phosphate ester. The flavodoxin structure contains a 5 stranded beta sheet surrounded by 5 alpha helices. The binding site for the FMN cofactor is located at the c-terminus of the beta sheet. Three forms of flavodoxin exist: Oxidized, (OX) semiquinone, (SQ) and hydroquinone (HQ). Two structural classifications for flavodoxins exist, short chain (~150 amino acid residues) and the long chain versions, which include a ~20 amino acid residue addition to the last strand in the beta pleated sheet. Although structurally unrelated, flavodoxins serve a nearly identical purpose to cyanobacteria as ferredoxins and are expressed during environmental stress in place of ferredoxins. Flavodoxins have potential medical, and biotechnical applications. Heliobacter pylori, the most prevalent human gastric pathogen, requires flavodoxins in its POR (pyruvate oxidoreductase enzyme complex) used to decarboxylate pyruvate. Most flavodoxins have a large hydrophobic residue near the isoalloxazine ring of its FMN cofactor, but Hp has an alanine residue instead, allowing for a pocket of solute to exist. Current research is being done to inhibit Hp specific flavodoxin for the purpose of treating infection.