PYRIDINE NUCLEOTIDES IN MITOCHONDRIA 223 



(State 4) and especially in a P, -deficient medium. The one preparation 

 (E044) without "extra DPN " contained it after incubation with suc- 

 cinate. It is noteworthy that, in disagreement with our finding with rat- 

 liver mitochondria (Table VIII), more "extra DPN" was found on 

 incubation of heart sarcosomes in P,-deficient medium than in ADP- 



TABLE X 



Reduction of DPN + brought about by adding Succinate to ADP-Deficient 

 Rabbit-Heart Sarcosomes in Presence of Glutamate 



Unpublished experiments of M. Bailie. Values in /Limoles/g. protein. 



deficient medium. This is probably related to the fact that the degree of 

 respiratory control is much greater with sarcosomes oxidizing succinate in 

 a Pj-deficient medium than in an ADP-deficient medium. 



The "extra DPN " is not derived from TPN. In Expt. 066, the freshly 

 prepared sarcosomes contained TPN +, 0-58; TPNH, 0-73; "extra 

 TPN", 0-26 /xmole/g. protein. 



TABLE XI 



Reduction of DPN + by Addition of Succinate (90 sec. at o") to Rabbit- 

 Heart Sarcosomes 



Unpublished experiment of M. Bailie (H071). Sucrose, o-i8 M; succinate, 

 40 m.M. Values in /xmoles/g. protein. 



In the course of these experiments, we have repeated Chance and 

 Hollunger's [19] observation on the effect of adding succinate to sarco- 

 somes in State 4 (i.e. deficient in ADP) in a medium already containing 

 glutamate. Our results agree with those of these authors in that succinate 

 brought about a considerable reduction of the DPN (Table X). Addition 

 of succinate to the sarcosomal suspension for only 90 sec. at o (cf. Tables V 

 and VI) also caused the appearance of much DPNH (Table XI). 



