CYTOCHROME SPECTRA 



483 



0.6 



^ 0.5 

 o 



z 



m 0.4 



on 



o 



en 



00 0.3 



< 



0.2 

 0.1 



o 2 



< 

 m 



§ 0.1 



CO 



: 



-0. 



400 



450 500 550 



WAVELENGTH (m;j) 



600 



Fig. 3. Chromatium (strain D) cytochrome 553 ferro- and ferri- 

 absolute spectra (A), ferro-minus-ferri- difference spectrum (B), 

 CO-ferro- absolute spectra (C), and CO-ferro-minus -ferro- dif- 

 ference spectrum (D) at pH 7 (50 mM potassium phosphate buffer), 

 d = 1.0 cm. For the CO spectra the gas phase is 1 atmos. CO. The 

 heme concentration for the visible region spectra is 20.7 //M (x 

 1/3 = 6.7 i«M cytochrome concentration) and for the Soret region 

 is 6.7 /UM for A and B, and 3.45 \m. for C and D. (Note added in 

 proof. The soret peaks in (A) are accidentally displaced 10 m/i to 

 the left relative to the wavelength scale.) 



