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R. W. ESTABROOK 



obtains a resolution of the a absorption bands associated with the cyto- 

 chromes h, c and c\ of heart muscle. Indeed, this method is the most sensitive 

 for determining the presence of cytochrome c^ and distinguishing cytochrome 

 c from cytochrome c^. 



An extension of this type of study is the spectrum shown in Fig. 17 of the 

 respiratory pigments of sarcosomes isolated from the flight muscles of the 



Fig. 16. The low temperature spectra of the reduced haemoproteins of a Keilin 

 and Hartree heart muscle preparation. Samples of heart muscle preparation 

 were diluted with 01 m phosphate buffer, pH 7-4, appropriate reagents added, and 

 then mixed with an equal volume of glycerol. Curve A represents the spectrum 

 of the oxidized pigments while curve B shows those pigments reduced by 

 succinate in the presence of cyanide and curve C represents those reduced by 

 NaoSjOi. Optical depth was 1 mm. Condition II. 



fly (Estabrook and Sacktor, 1958). These studies, carried out with Dr. 

 Sacktor, show the apparent absence of cytochrome q in this type of material. 

 It is known from other studies, however, that although cytochrome q 

 appears to be absent, a pigment functioning similarly to cytochrome q but 

 of entirely different absorption characteristics is present. 



Another type of material studied was the cytochrome complement of 

 wheat germ mitochondria as presented in Fig. 18. This work was carried out 

 with Dr. Stern of the University of Toronto. Again one sees variation in the 

 type of cytochrome spectra obtained. The spectral properties of the cyto- 

 chromes of plants will be described in greater detail by Dr. Bonner at this 

 symposium. Thus it appears that every new source that we have tried shows 

 a variability in cytochrome pattern. One must admit that it becomes most 



