Flavodoxins are low-potential electron donors to a number of redox enzymes. AvFld 1 is able to donate electrons to the assimilatory nitrate reductase of A.vinelandii to catalyze the reduction of nitrate to nitrite. E(0) is -330 mV. It is the mid-point potential of the semiquinone/hydroquinone redox couple (SQ/HQ) of AvFld 1. Is the predominant flavodoxin expressed when A.vinelandii is grown on nitrate as nitrogen source. Belongs to the flavodoxin family.