Discussion on Hydrogen Transport 



VAN R. POTTER 

 University of Wisconsin, Chairman 



Dr. Potter: 



This afternoon's discussion has been organized with the idea of 

 studying some of the problems which may be considered as open 

 questions at this time. The first speaker will be Dr. Elliott. 



THE POSSIBLE ROLE OF INTERMEDIARY METABOLITES 



AS HYDROGEN CARRIERS 



K. A. C. ELLIOTT 



Institute of the Pennsylvania Hospital 



This subject has not been reviewed at length during this sym- 

 posium, and it is impossible to cover it fully in a brief discussion. 

 Some famiharity with the subject will therefore be assumed, and 

 only certain outstanding problems will be discussed. (For details and 

 bibliographies see references 1-3.) 



The most important theory of intermediary metabolites as hydro- 

 gen carriers is that of Szent-Gyorgyi. It may be represented by the 

 following highly simplified diagram, in which heavy arrows indicate 

 transfers of hydrogen atoms (or electrons) from one substance to the 

 next. 



OONATORS OXALACETATE FUMARATE REDUCED CYTOCHROME 



I .2H^ il Jil^ It .2H^ n -^^OXYGEN 



^^ ^^, ., MALATE SUCCINATE OXIDIZED CYTOCHROME 



OXIDIZED DONATORS 



According to this theory, hydrogen from tissue donators reduces 

 oxalacetate to malate; the malate is reoxidized to oxalacetate and the 

 hydrogen is transferred to fumarate, reducing it to succinate; and 

 the succinate is then reoxidized to fumarate by the cytochrome- 

 cytochrome oxidase system. Malate-oxalacetate and succinate- 

 fumarate thus perform functions similar to that of reduced cyto- 

 chrome-oxidized cytochrome. Known dehydrogenases and cozymase 

 are concerned in the catalysis of the various steps; also, a flavo- 

 protein was believed by the Szent-Gyorgyi school to mediate in the 

 reduction of fumarate by malate. 



Considerable evidence that this mechanism can function in 

 pigeon breast muscle brei has been adduced by the Szent-Gyorgyi 



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