154 M. I). KAMEN 



TABLE III. Cytochrome Components of Green Sulfur Bacteria (13,17) 



C. limicola, cytochrome-553 : see (17) 



Absorption maxima (reduced) 553, 520, 415 mju 



Reaction with CO in reduced form None 



Autoxidation Slow 



C. ihiosulfaiicum, cytochrome-554 (1); see (13) 



Absorption maxima (reduced) 554, 523, 417 m;u 



Absorption maxima (NO-compound-oxidized) 573, 537 m/j. 



Reaction with CO in reduced form None 



Autoxidation Slow 



Fe content 0.37% 



Hematin content 3.1% 



£'o'(pH7) ~ +0.160 volt 



Concentration in cells '^0.1% dry weight 



cation beyond that achieved by exhaustive electrophoresis of crude 

 ammonium sulfate fractions has not been obtained. 



The properties of the purest preparation obtained are shown in 

 Table IV. At least two protein components are present. One of these 

 binds a heme group similar to that found in mammalian cytochrome 

 c. There is nonheme iron apparently present in some as yet unspeci- 

 fied form. While the compound is slowly autoxidizable and exhibits 

 spectroscopic behavior reminiscent of cytochrome c, it has a low 

 redox potential. Thus, it, too, falls into no recognized single class of 



TABLE IV. Properties of Chromatium Cytochrome (26) 



Absorption maxima (mp) 



Ferrocytochrome 552, 525, 418 (shoulder at 423) 



Ferricytochrome — , — , 406 



Reduced cyanide hemochi'omogen 553, 527, 419 



Reduced pyridine hemochromogen 551, 519, 412 



Porphyrin in ether 632, 575, 532, 503, 375 

 Ratios of ferrocytochrome maxima 



270/552 8.57 



418/552 9.8 



552/525 116 



Anodic mobility, pH 6.0 5.9 X 10-« cm.Vvolt-sec. 



" " , pH 7.8 6.26 X 10-6 cm.Vvolt-sec. 



8.43 X 10-5 cm.Vvolt-sec. 



Fe content, % protein 0.12 



Ratio ; Fe/Heme 2 . to 2 . 7 



^'o (pH 7) -0.04 volt 



