To corroborate our evolutionary hypothesis concerning the emergence of the OLEFs around the Fe2 and Fe6 sites in FeMoco, we analyzed the electrostatic environments of these potential N2-coordination sites across the entire family of FeMoco nitrogenases (cf. Gratifyingly, the same qualitative trend is observed in all of these. In fact, for the field along the Fe2-Fe6 axis, we observe that for some nitrogenases, the field strength tends to be even higher than for 3U7Q, reaching values as high as -0. OLEFs were consistently calculated without taking the influence of (the equivalent residue to) His195 into account.