The hemoprotein content of Chromatium sp. strain D

1. The hemoprotein content of autotrophic Chromatium strain D has been measured from difference spectra, using solvent-extracted and intact cells.

2. The quantities of the individual cytochromes were estimated by absorbance differences at single wavelengths and by peak-trough differences in spectra obtained from reduced versus oxidized, and CO-treated reduced versus reduced preparations. The concentrations found in intact cells weer 1.15, 0.49 and 0.56 nmoles heme per mg protein for cytochromes c₅₅₃, cc′ and , respectively. In intact cells, the corresponding values were 1.33, 0.47 and 0.67 nmoles heme per mg protein.

3. The mesoheme content of the cells, estimated as pyridine hemochromogen, was 2.08 nmoles heme per mg protein, while the amount of protoheme was negligible.