Figure 2.

Gated electron transfer in nitrogenase. Shown is a schematic of gated electron transfer from the Fe protein to half of the MoFe protein. The electron transfer event is initiated by association of the Fe protein with the MoFe protein (left). In this state, the gate for electron transfer is closed (shown as a blue bar). Next follow protein conformational changes in the complex that result in the uptake of about 80 water molecules (center). The electron transfer gate is opened (shown as two blue lines), allowing electron transfer (red arrow) to occur (right).