Ferredoxins can be classified according to the nature of their iron-sulfur clusters and by sequence similarity.

There are several types of iron-sulfur cluster.

Iron-sulfur clusters are ensembles of iron and sulfide centres.

'C': conserved cysteine involved in the binding of the iron-sulfur cluster.

The subunit is an iron-sulfur protein with three iron-sulfur clusters.

This metal nitrosyl was first described in 1858, making it the first synthetic iron-sulfur cluster.

The function of frataxin is not entirely clear, but it seems to be involved in assembly of iron-sulfur clusters.

Iron-sulfur clusters exist at the center of many important enzymes, Dr. Pace noted.

Well studied examples include iron-sulfur clusters, oxyhemoglobin, ferritin, and the cytochromes.

The electrons are then transferred through a series of iron-sulfur clusters: the second kind of prosthetic group present in the complex.

In addition, they proposed a role of the iron-sulfur cluster in adenosine-5'-phosphosulfate reduction.

Iron-sulfur clusters are best known for their role in the oxidation-reduction reactions of mitochondrial electron transport.

Ferredoxins are small proteins containing iron and sulfur atoms organized as iron-sulfur clusters.

The NiFe-hydrogenases contain nickel in addition to iron-sulfur clusters.

Finally, the electrons are transferred from the chain of iron-sulfur clusters to a ubiquinone molecule in the membrane.

Within proteins, electrons are transferred between Flavin group cofactors, iron-sulfur clusters, and cytochromes.

The iron-sulfur clusters are pervasive and include nitrogenase, the enzymes responsible for biological nitrogen fixation.

Type I photosystems use ferredoxin-like iron-sulfur cluster proteins as terminal electron acceptors.

As shown in the following schematic representation the iron-sulfur cluster is bound by four conserved cysteine residues.

This is especially appropriate for proteins that need co-factors, such as iron-sulfur clusters and molybdopterin, which are incorporated in the cytoplasm.

Inorganic sulfur forms a part of iron-sulfur clusters as well as many copper, nickel, and iron proteins.

Almost all hydrogenases contain at least one iron-sulfur cluster (Fe-S cluster).

Iron-sulfur clusters are complexes of iron and sulfur atoms held within proteins by cysteinyl residues.

The latter can be pigments (like chlorophyll, pheophytin, carotenoids), quinones, or iron-sulfur clusters.