FIGURE 3.

Purification of recombinant M. acetivorans D-L(His) and D-L(His)-FeS heterodimers. A, anaerobic size exclusion chromatography of eluate (∼50 mg of total protein) from Ni²⁺ affinity chromatography of E. coli cell lysate containing M. acetivorans subunit L(His) and subunit D. B, same as A except that the eluate was reconstituted with iron and sulfide prior to loading onto the size exclusion column (see “Experimental Procedures” for details). For each purification, samples from fractions containing peaks 1, 2, and 3 were analyzed by SDS-PAGE as indicated. The asterisk indicates the peak that is consistent with a the molecular mass of a D-L(His) heterodimer (40.2 kDa). mAU, milliabsorbance units.