ALTERNATIVE PATHWAYS OF ELECTRON 

 TRANSPORT 



C. Martius 



Department of Biochemistry, 

 Eidg. Technische Hochschule, ZUrich 



Some years ago, the idea was put forward (Martius, 1954) 

 that there may exist in the mitochondria two different routes 

 for the transport of hydrogen atoms or electrons, respectively, 

 between the pyridine nucleotides and cytochrome c, only one 

 of them being linked with the enzymes which bring about 

 phosphorylation. The so-called classical route, which leads 

 from diphosphopyridine nucleotide (DPN) to cytochrome c 

 reductase and then to cytochrome c or first to c^, is not, in my 

 opinion, connected with the formation of high-energy phos- 

 phate bonds. This should be the task of the second alternative 

 pathway in which vitamin K plays an important role. These 

 concepts, especially the one concerning the role of vitamin K, 

 have not been accepted very enthusiastically by the experts, 

 although Chance and Williams (1956), for instance, seem to 

 agree on the concept regarding the possibility of the existence 

 of two pathways for the hydrogen atoms. The main idea that, 

 besides the known representatives of this class, vitamin K 

 should react as an oxidation-reduction catalyst, was the one 

 which seemed strange and unconvincing. 



The present author's reasons for continuing to support this 

 concept are given here, and its possible significance for the 

 general problems of this symposium are discussed briefly. The 

 crucial point of the scheme is the link between the pyridine 

 nucleotides and vitamin K. Some time ago we reported 

 (Martius and Strufe, 1954) the detection in mitochondria of an 

 enzyme, phylloquinone reductase, which should represent the 

 missing link. We now know that our first preparations con- 



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