38 A SYMPOSIUM ON RESPIRATORY ENZYMES 



few, if any, of the metabolites can be singled out as specially con- 

 cerned in the hydrogen transport. (This view of the mechanism was 

 suggested to me by Dr. Potter.) 



REFERENCES 



1. Szent-Gyorgyi, a., Studies in Biological Oxidation (Leipzig, 1937). 



2. Stare, F. J., and Baumann, C. A., Cold Spring Harbor Symposia on Quan- 

 titative Biology, 7, 277 ( 1939). 



3. Elliott, K. A. C, Physiol. Rev., 21, 267 ( 1941). 



4. Ball, E. G., Cold Spring Harbor Symposia on Quantitative Biology, 7, 

 100 (1939). 



5. Martius, C, Ergebnisse Enzymforschung, 8, 247 (1939). 



6. Potter, Van R., Medicine, W, 441 (1940). 



Dr. Potter: 



The second question to be considered is the role of the carriers in 

 dismutations and coupled oxidoreductions.* Since it is agreed 

 that the various metaboHtes may take part in coupled oxido- 

 reductions, it becomes of interest to determine how these reactions 

 may be brought about, and what features these "fermentation" re- 

 actions have in common with the oxidative mechanisms. Dr. Ball and 

 Dr. Lipmann will open the discussion. 



THE ROLE OF THE CARRIERS IN DISMUTATIONS AND 



COUPLED OXIDOREDUCTIONS 



With Special Reference to the Flavoproteins 



Eric Ball, Harvard University: 



The chief carriers that play a role in dismutations or coupled 

 oxidoreductions are the pyridine nucleotides and flavoproteins. 

 Since the participation of the pyridine nucleotides in such reactions 

 is more common, examples of dismutations and of coupled oxido- 

 reductions involving diphosphopyridine nucleotide may be given 

 first. 



The classical example of a dismutation is the so-called Cannizzaro 

 reaction, which may be represented by the following equations: 



(1) R-CHO + 2e + 2H^->R-CH20H 



(2) R-CHO-f H2O — 2e-2H*^R-COOH 

 (1) + (2) 2RCHO + H20->R-CH20H-f R-COOH 



" This term was not included in the original statement of the question. Dr. 

 Barron rose to point out that the term "dismutation" has a very narrow applica- 

 tion and that "coupled oxidoreduction" is the more general expression. 



