Nitrogenase_VFe_alpha -like: Nitrogenase VFe protein, alpha subunit like. This group contains proteins similar to the alpha subunits of, the VFe protein of the vanadium-dependent (V-) nitrogenase and the FeFe protein of the iron only (Fe-) nitrogenase Nitrogenase catalyzes the ATP-dependent reduction of dinitrogen (N2) to ammonia. In addition to V- and Fe- nitrogenases there is a molybdenum (Mo)-dependent nitrogenase which is the most widespread and best characterized of these systems. These systems consist of component 1 (VFe protein, FeFe protein or, MoFe protein respectively) and, component 2 (Fe protein). MoFe is an alpha2beta2 tetramer, V-and Fe- nitrogenases are alpha2beta2delta2 hexamers. The alpha and beta subunits of VFe and FeFe are similar to the alpha and beta subunits of MoFe. For MoFe each alphabeta pair contains one P-cluster (at the alphabeta interface) and, one molecule of iron molybdenum cofactor (FeMoco) contained within the alpha subunit. The Fe protein which has a practically identical structure in all three systems, it contains a single [4Fe-4S] cluster. Electrons are transferred from the [4Fe-4S] cluster of the Fe protein to the P-cluster of the MoFe and in turn to FeMoCo, the site of substrate reduction. The V-nitrogenase requires an iron-vanadium cofactor (FeVco), the iron only-nitrogenase an iron only cofactor (FeFeco). These cofactors are analogous to the FeMoco. The V-nitrogenase has P clusters identical to those of MoFe. In addition to N2, nitrogenase also catalyzes the reduction of a variety of other substrates such as acetylene The V-nitrogenase differs from the Mo-nitrogenase in that it produces free hydrazine, as a minor product during dinitrogen reduction and, ethane as a minor product during acetylene reduction.
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