Figure 6. Analysis of heme binding to purified P. gingivalis HmuY and T. forsythia Tfo under different redox conditions examined by UV-visible spectroscopy.

(A) Colors of 150 μM HmuY and Tfo proteins complexed with heme (protein:heme ratio 1:1) in PBS are shown. (B,C) UV-visible absorption spectra of HmuY–heme and Tfo–heme complexes are presented. Samples (10 μM proteins) in complex with heme were examined under air (oxidizing) conditions and subsequently reduced by sodium dithionite, and re-oxidized by potassium ferricyanide.