FIGURE 8.

Heme-induced oligomerization of PgDps dodecamers. The oligomeric state of PgDps bound to heme in solution was determined by SEC-MALLS. PgDps was pre-incubated with heme at the molar ratio of 1:1 in 50 mm Tris-HCl, pH 8.0, 150 mm NaCl at 37 °C. Molecular mass values of three main elution peaks were calculated using a dn/dc value of 0.185. Heme induced PgDps to form progressively higher oligomeric species over time. Molecular mass of the oligomeric species eluted as peak 1 was calculated at 2471 kDa, which is approximately equal to the molecular mass of 10 dodecamers. The higher oligomeric species could be dissociated back to the predominant dodecameric form after incubation with 2 mm TCEP.