The spectrophotometric titration of apo-C14A/M69A with the ferric heme <i>b</i>.

(A) The apo-protein is reconstituted with the ferric heme b to yield a corresponding 5-coordinated heme species. The arrows indicate the direction of change in absorbance intensity with the addition of ferric heme-b. (B) The absorbance at 410 nm is plotted against Molar ratio of [heme]/[apo-C14AM69A], showing a saturation of the Soret band.