Nucleotides and Mitochondrial Function: Influence of 

 Adenosinetriphosphate on the Respiratory Chain 



Martin Klixgenberg 



PhysiologiscJi-CJiemiscJies Institut der Universitdt, 

 Marburg, Germa?iy 



It has been known since the discovery of oxidative phosphorylation 

 that electron transport of the respiratory chain effects the phosphorylation 

 of the adenine nucleotide system. The reverse control of electron transport 

 bv the phosphorylation of the adenine nucleotides has been demonstrated 

 with the influence of ADP on respiration and on the redox state of nucleo- 

 tides and cytochromes of the respiratory chain [cf. i, 2, 3]. It could be 

 shown only recently that the redox state of the respiratory chain can also 

 be influenced by ATP in a reversal of the oxidative phosphorylation 



[4, 5, 6]. 



The relation between the ATP level and electron transport, as followed 

 by the respiration and the redox state of the respiratory chain, is the subject 

 of studies presented in this article. This aspect will be pursued both with 

 respect to the intramitochondrial ATP as well as to the eflect of external 

 ATP. In this context we are concerned with the reversal of the oxidative 

 phosphorvlation, which was postulated to take place in the succinate and 

 glycerolphosphate induced DPX reduction in mitochondria [7, S, 9, 10]. 

 Some related data on the major intramitochondrial nucleotide systems will 

 be presented first. 



Intramitochondrial nucleotide systems 



The anion exchange chromatograms of Fig. i give an example of the 

 pattern and behaviour of intramitochondrial nucleotides in two difl^erent 

 functional states [11]. Only the pyridine and adenine nucleotide systems 

 can be extracted in appreciable amounts from these muscle mitochondria. 

 The concentration of reduced pyridine nucleotide in the perchloric acid 

 extract of mitochondria is quantitatively determined bv the concentration 

 of the acid decay products of DPXH (ADP-ribose) and of TPNH (ADP- 

 ribosephosphate) [12]. In confirmation of the results obtained by other 

 methods, in the presence of succinate DPN is mostly reduced, whereas in 

 the presence of dinitrophenol, DPN is oxidized. Similar but smaller 

 changes are observed with the TPN system. As expected, in the presence 



