/ 



The Location of Cytochromes in Escherichia Coli 223 



In conclusion, the ghosts formed under the conditions of this experiment 

 bear all the cytochromes of the cell. This suggests that in E. coli the respira- 

 tory chain is located in the cell membrane. 



CONCLUSION 



There is no evidence in bacterial cells for respiratory granules homogeneous 

 in size and shape: the cytochromes are usually attached to granules of 

 widely different sizes in the extracts and these granules probably derive from 

 the breakdown of a larger structure, the cell membrane (Marr and Cota- 

 Robles, 1957). Under some conditions, all the cytochrome system is bound to 

 'ghosts' or cell membrane preparations, however probably containing still 

 some wall material. The ribonucleoprotein particles, which are uniform in 

 size and seem to fill the bacterial cytoplasm (Tissieres et al., 1959) do not bear 

 any cytochrome pigments. 



SUMMARY 



1. In £". coli extracts granules bearing cytochromes can be separated from 

 ribonucleoprotein particles. 



2. 'Ghosts' lysed in the presence of 0-01 m magnesium ions contain all the 

 cytochromes of the cell. 



Acknowledgement 



I wish to thank Dr. N. Krinsky for measuring the difference spectrum 

 shown in Fig. 1. 



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DISCUSSION 



The Origin of the Respiratory Granules of Bacteria 



Slater : The respiratory granules derived from the disintegration of the bacterial membrane 

 which can be isolated by the methods described by Tissieres are capable of carrying 



