4Fe-4S binding domain <p>This superfamily includes proteins containing domains which bind to iron-sulphur clusters. Members include bacterial ferredoxins, various dehydrogenases, and various reductases. Structure of the domain is an alpha-antiparallel beta sandwich.</p><p>Ferredoxins are iron-sulphur proteins that mediate electron transfer in a range of metabolic reactions; they fall into several subgroups according to the nature of their iron-sulphur cluster(s) [<cite idref="PUB00003397"/>, <cite idref="PUB00003406"/>]. One group, originally found in bacteria, has been termed "bacterial-type", in which the active centre is a 4Fe-4S cluster. 4Fe-4S ferredoxins may in turn be subdivided into further groups, based on their sequence properties. Most contain at least one conserved domain, including four Cys residues that bind to a 4Fe-4S centre. </p>