AEROBIC PHOSPHORYLATION IN R. RUBRUM 



169 





2- 







DP/VH 



M-6-PII 



2 4 6 8 10 

 Fraction 



Fig. 4. Effect of Combining Fractions on Aerobic 

 Phosphorylation— Crude dark extract, 8.0 mg protein, 

 was centrifuged in a sucrose density gradient for forty 

 five minutes at 35,000 rpm, fractionated and analyzed 

 as in Fig. 1. Succinic dehydrogenase and DPNH oxidase 

 activities were assayed at 30°C. One arbitrary unit 

 represents: for succinic dehydrogenase (squares), 

 5.4 myU moles indophenol reduced /ml /min; for DPNH 

 oxidase (triangles), 7.0 m/Umoles DPNH oxidized/ml/ 

 min; and for M-6-P (curve M-6-P-I), 4.9 m^moles 

 M-6-P formed/ml/min. Curve M-6-P-II represents 

 the assay of PMS-sensitive aerobic phosphorylation 

 carried out in the same manner as for M-6-P-I, ex- 

 cept that equal volumes of fraction 5 were also added. 

 The dashed curve was calculated by adding theM-6-P 

 value for fraction 5 (in curve M-6-P-I) to the values 

 obtained for each fraction in curve M-6-P-I. 



