Nitrogenase alpha chain (IPR005974)

Short name: Nase_asu

Overlapping homologous superfamilies


Family relationships


The enzyme responsible for nitrogen fixation, the nitrogenase, shows a high degree of conservation of structure, function, and amino acid sequence across wide phylogenetic ranges. All known Mo-nitrogenases consist of two components, component I (also called dinitrogenase, or Fe-Mo protein), an alpha2beta2 tetramer encoded by the nifD and nifK genes, and component II (dinitrogenase reductase, or Fe protein) a homodimer encoded by the nifH gene. Two operons, nifDK and nifEN, encode a tetrameric (alpha2beta2 and N2E2) enzymatic complex. Nitrogenase contains two unusual rare metal clusters; one of them is the iron molybdenum cofactor (FeMo-co), which is considered to be the site of dinitrogen reduction and whose biosynthesis requires the products of nifNE and of some other nif genes. It has been proposed that NifNE might serve as a scaffold upon which FeMo-co is built and then inserted into component I.

This model represents the alpha chains of various forms of the nitrogen-fixing enzyme nitrogenase: vanadium-iron, iron-iron, and molybdenum-iron. Most examples of NifD, the molybdenum-iron type nitrogenase alpha chain, are excluded from this model and described instead by equivalog model IPR005972.

GO terms

Biological Process

GO:0009399 nitrogen fixation
GO:0055114 oxidation-reduction process

Molecular Function

GO:0051536 iron-sulfur cluster binding
GO:0016163 nitrogenase activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.