FIG. 1.

Spectral evidence for heme transfer from holo-Shp to apo-HtsA. (A) The shift over time in the Soret absorption peak of a mixture containing 6.5 μM holo-Shp and 13.3 μM apo-HtsA at room temperature. The spectra of apo-HtsA alone (solid curve) and holo-Shp alone (dashed line) are included for comparison. (B) The Soret absorption peaks of 10 μM holo-Shp alone (solid circles) and a mixture of 10 μM holo-Shp and 18 μM SPy0252 (open circles). The spectrum of the holo-Shp/SPy0252 mixture was obtained 1 h after the proteins were mixed.