296 



Fulvio Perini 



0.6 



0.5 



04 



.a 0.3 



< 



02 



0.1 



Cytochrome b-561 



peroxidase axid an a-type cytochrome (fig. 3). See also Table 1, 

 This observation \'ra,s con- 

 firmed by the preparation 

 of pyridine haemochromogens 

 and determination of proto- 

 haem a by paper chromatog- 

 raphy. Peroxidase assays 

 were negative, save for a 

 small amount of activity 

 due to denatvired cytochrome 

 552. The b-type cytochrome, 

 which was called cytochrome 

 b-561, is probably identical 

 to the bg observed by 

 Smillie {3). This protein 

 could not be solubilized 

 and was found to be present 

 in 1:1 ratio to cytochrome 

 c-552. 



520 



560 600 



Wavelength (mu) 



Fig. 3. Reduced-oxidized differ- 

 ence spectra of cytochromes 

 b-561 and a-605. 



The autooxidizable 

 compound (the maximum at 

 600 m|j in fig. 3 is due 

 to autooxidation) identified 

 as an a-type cytochrome was 



called cytochrome a-605 etnd was found in all mutant strains and 

 wild type forms of Euglena gracilis in 1:1 ratio to cytochrome 

 556. It was sensitive to cyanide and to low oxygen tension. 



LOCALIZATION AM) FUNCTION OF CYTOCHROMES IN EUGLENA 



Cytochrome c-552 has been localized in the chloroplasts, 

 whereas cytochrome 556 occurs in small particles, which we 

 believe to be mitochondria. In both cases the procedure used 

 was similar to that used by Smillie ^5j for the preparation of 

 chloroplasts from dried cells by suspending them in a mixture of 

 carbon tetrachloride and cyclohexane. The cells were broken in 

 a French press and then fractionated, using solvent mixtvires of 

 different specific gravity. 



Mutants which have no chloroplasts have no cytochrome c-552, 

 while smaller amounts of the protein were fo\ind in a mutant with 

 damaged chloroplasts. 



The parallel syntheses of cytochromes c-552 and chlorophyll 

 were follov;ed, and no cytochrome appears to be present in the 



