FIG. 3.
Determination of the stoichiometry of Fur-DNA complexes by native PAGE. (A) Logarithms of the relative mobilities of Fur-DNA and marker proteins (versus the mobility of bromophenol blue) as a function of polyacrylamide concentration. The complexes used were Fur-(7-1-7) (□) and Fur-[(7-1-7)2] (○). The marker proteins used were carbonic anhydrase (⧫), α-lactalbumin (▪), bovine serum albumin dimer (•), bovine serum albumin monomer (▾), and ovalbumin (▴). (B) Determination of the apparent molecular weights of the Fur-(7-1-7) and Fur-[(7-1-7)2] complexes. The negative slopes of the mobility lines in panel A were plotted against the molecular weights of the protein standards (solid symbols), and the apparent masses of the Fur-DNA complexes (open symbols) were determined by interpolation.