448 



R. W. ESTABROOK 



anomalous property of this pigment is the very high extinction of the /i bands. 

 In addition it must be mentioned that cytochrome Z)4 is really not a ^-type 

 cytochrome but has proven to be a c-type cytochrome. This is evidenced by 

 the location at 549 mw of the alpha band of its reduced alkaline haemo- 

 chrome. The impure samples of cytochrome b^ first reported by Egami, 

 Itahashi, Sato and Mori (1953) have since been shown to be contaminated 

 by another haemoprotein with a typical b-typQ absorption spectrum. 



Cytochromes b^, bg and bg 



Spectral studies have been carried out on cytochrome b^ of anaerobic 

 yeast, cytochrome b^ (yeast lactic dehydrogenase) and cytochrome b^ of 



Fig. 



WAVELENGTH ( m;j ) 

 12. The low temperature absorption spectra of cytochromes b^ and h.^. 



Solid line: cytochrome b^ in intact cells of anaerobically grown yeast, stationary 



phase of growth, reduced with NaaS.jOi. The dashed line represents cytochrome 



bo purified from baker's yeast, reduced with Na2S20i. Optical depth was 



1 mm. Condition II. 



liver microsomes. All three pigments show essentially the same type of 

 absorption spectrum at low temperature (Chance, Klingenberg and Boeri, 

 1956; Lindenmayer and Estabrook, 1958). As shown in Fig. 12 one observes 

 a split of the a-band of reduced cytochromes /;, and /^a; it should be noted 

 that in contradistinction to the fine band structure observed with the a-band 

 of reduced cytochrome c of heart muscle, the band of lower extinction 



