Purification and properties of nitrogenase from Rhodospirillum rubrum, and evidence for phosphate, ribose and an adenine-like unit covalently bound to the iron protein

Abstract

The Mo-Fe protein, Fe protein and the activating factor of nitrogenase from R. rubrum were purified. The Mo-Fe protein has properties similar to those of the Mo-Fe proteins of other N2-fixing organisms [bacteria]. The Fe protein is similar to other Fe proteins with respect to its MW, metal composition and EPR signal. The fe protein is different from other Fe proteins in that it apparently had 2 types of subunits rather than one, its UV spectrum has an extra peak, and phosphate, ribose and an adenine-like unit are covalently bound to the protein. The presence of these non-protein groups on the protein may explain the requirement for activation of R. rubrum Fe protein.