COUPLING OF REDUCED PYRIDINE NUCLEOTIDE OXIDATION 1 79 



importance. On the other hand, if a relation exists between the function of 

 DT diaphorase, the biological activity of dicoumarol, and the nutrition 

 requirement for vitamin K in the animal organism, then a much more 

 specific role for DT diaphorase must be found. 



References 



1. Chance, B., and Hess, B.,^. biol. Chcni. 234, 2404 (1959). 



2. Colpa-Boonstra, J. P., and Slater, E. C, Biochitn. biophys. Acta 27, 122 (1958). 



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8. Ernster, L., this volume, p. 139. 



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Discussion 



Peters : Were these citrate experiments done \\ ith mitochondria ? 



Conover: They were done with liver slices. 



Peters: I wasn't quite sure why you used citrate rather than isocitrate. 



Conover: Well the primary reason was that the isocitrate we had was in the 

 lactone form and we weren't quite sure whether this would be readilv oxidized. 



Low'ENSTEiN : W^hat concentration do you add ? 



Conover: Usually lo ■' ^L Actually the experiments shown did not give the 

 effect of TPN alone. It is not as high when added by itself as when added in the 

 presence of vitamin K:j. 



LowENSTEiN : The other question I wanted to ask was : are the TPN diaphorase 

 activities found in the cytoplasm and the mitochondria the same ? 



Conover: They are, as far as we have been able to tell. We have isolated the 

 mitochondrial DT diaphorase and it exhibits identical properties with the cvto- 

 plasmic DT diaphorase. 



