Abstract:When the reduced MoFe protein from Azotobacter vinelandii Lipmann was treated with ophenanthroline and air, an inactive protein partially deficient in both FeMoco and P-cluster could be obtained. After incubating the treated protein with a reconstituent solution containing Re2OT, ferric homocitrate, Na2S and dithiothreitol, which had no circular dichroism (CD) signal, the ultraviolet and visible CD spectra, the C2H2 and H+ -reduction activity of the incubated protein were significantly recovered. However, the spectra were somewhat different from those of the reduced MoFe protein. The results showed that: 1) in the incubated protein solution there was possibly a new recombined ReFe protein besides the intact MoFe protein which was not destroyed by the treatment with o-phenanthroline and air; 2) it might be possible that both ReFe protein and MoFe protein exhibited similar ability of nitrogen fixation, although they were somewhat different in structure.