Differentiation of acetylene-reduction sites by stereoselective proton addition during Azotobacter vinelandii nitrogenase-catalyzed C(sub 2)D(sub 2) reduction

The effects of changing the c(sub 2)D(sub2) concentration, electron flux, pH, or the individual presence of N(sub 2), ethylene, or CO on the formation of both cis- and trans-1,2-ethylene-d(sub 2) from C(sub 2)D(sub 2) are monitored. The factors influencing stereoselective protonation during C(sub 2)D(sub 2) reduction is the same as that of the FeMo cofactor when acetylene is reduced.