SOME OBSERVATIONS CONCERNING THE PURIFICATION 

 AND PROPERTIES OF THE AEROBIC 

 PHOSPHORYLATION SYSTEM OF 

 R. RUBRUM EXTRACTS 1 



DAVID M. GELLER 



Department of Phaniiacology, Washington University School of Medicine 

 St. Louis, Missouri 



INTRODUCTION 



Previous work (1) demonstrated that cell-free extracts of R. nib- 

 rum carry out an aerobic phosphorylation of adenosine diphosphate 

 in the absence of light. By means of differential centrifugation, the 

 aerobic phosphorylation system of extracts of cells grown aerobically 

 in darkness was found to consist of soluble dehydrogenases and a 

 particulate complex which catalyzed phosphorylation of adenosine 

 diphosphate associated with the oxidation of DPNH. 



The following is a report of results of a further analysis of /2. 

 rubrum extracts by centrifugation in sucrose density gradients. This 

 work indicates that the bulk of the DPNH oxidase activity of crude 

 extracts of cells grown aerobically in darkness is associated with 

 particles which are lighter than those which catalyze aerobic phos- 

 phorylation with DPNH. The phosphorylation system appears to be 

 closely associated with succinic dehydrogenase activity. This aerobic 

 phosphorylation system, purified by centrifugation in sucrose density 

 gradients, has been characterized by its response to various inhibitors 

 of electron transport and phosphorylation. 



EXPERIMENTAL PROCEDURE 



Growth of bacteria and preparation of extracts 



Bacteria were grown aerobically in darkness or anaerobically in 

 light, harvested, and washed as previously described (1). 



Extracts derived from cells grown aerobically in the dark are 

 designated by the term "dark extracts" and extracts of cells grown 

 anaerobically in the light, by "photosynthetic extracts." 



1 This investigation was supported by Grant RG-7023 from The National Insti- 

 tutes of Health, U. S. Public Health Service. 



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