FIG. 6.

E. coli cells expressing membrane-associated rHmuR-6His bind porphyrins and metalloporphyrins. Binding to E. coli expressing 6His-rHmuR (grey bars), and to control E. coli harboring the vector alone (open bars) is shown. Black bars, differences between the two data sets. E. coli cells were resuspended in PBS and incubated for 1 h at RT with hemoglobin (5 μM) or porphyrins or metalloporphyrins (10 μM). Binding was determined by the decrease of absorbance at 400 nm of the supernatant and recorded as the percentage of the input porphyrins. Data are means ± SD from three independent experiments performed in duplicate. Hb, hemoglobin; Hm, hemin.