ELECTROMETRIC AND OTHER STUDIES ON 

 CYTOCHROMES OF THE C-GROUP 



By R. W. Henderson and W. A. Rawlinson 

 Department of Bioehemistry, University of Melbourne 



There is a very wide distribution in tissues, of pigments with a haemochrome- 

 type spectrum showing absorption peaks in the visible region close to 550 

 and 520 m/n. A number of haemochromes with different haem prosthetic 

 groups are known, however, to show a similar spectrum (see for example, 

 Lemberg and Legge, 1949; Morton, 1958) and from time to time it has been 

 pointed out that many of these compounds are as yet only spectral pheno- 

 mena. With the isolation of bacterial cytochromes (see for example, Kamen 



Table 1. Range of £"„' values found in cytochrome c group pigments 

 (see also Morton, 1958) 



Common 

 symbol 



Source 



Eo' (V) 



RHP-pigment 



Plants (chloroplasts) 

 Rhodospirillum rubrum 

 Mammalian heart-muscle 



Micrococcus denitrificans 

 Rhodospirillum rubrum 

 Desulphovibrio desulphur icons 



-I-0-365 

 +0-338 

 +0-255 



+0-250 

 -0008 

 -0-205 



Davenport & Hill (1952) 

 Kamen & Vernon (1955) 

 Rodkey & Ball (1950) 

 Henderson & Rawlinson (1956a) 

 Kamen & Vernon (1955) 

 Bartsch & Kamen (1958) 

 Postgate (1956) 



Table 2. Eq values obtained after modification of mammalian 

 heart-muscle cytochrome c 



Treatment 



Fraction separated on a resin column 



from TCA-extracted preps. 

 'Resin-purified' prep, treated with 2-5% 



TCAfor 18hr, 25°C 

 Proteinase-digested 



Henderson & Rawlinson (1956b) 

 Henderson & Rawlinson (1956b) 

 Minakami, Titani & Ishikura (1957) 



cf. Table 1, resin-purified cytochrome c, Eq = + 0-255 V. 

 370 



