FIG 4.

Reconstitution of nickel affinity-purified His₆-MBP-PpaA with hemin (vertical dotted lines at 361 and 412 nm). Purified protein was mixed with hemin in a 1:1 molar ratio and incubated overnight at 4°C. The spectrum of heme is red shifted, suggesting that PpaA does have some heme-binding capacity. Heme binding by the H146A mutant is less apparent, while the G149E mutant shows a more pronounced spectral change.