BIOGRAPHICAL MEMORANDA 



4. Condensation of acetaldehyde to acetyl methyl carbinol, or, via 

 acetaldol, to butyric acid ; and of acetic acid to aceto-acetic acid 

 followed by a decarboxylation to acetone and carbon dioxide. 

 The dehydrogenations mentioned under 5 were depicted as pro- 

 ceeding under the influence of the protoplasm of the fermenting cells, 

 yielding an oxidation product and 'protoplasm-H 2 '. Realizing that 

 the protoplasm would have to be continuously regenerated from its 

 reduced state, two types of suitable mechanisms were envisaged, viz., 



a. regeneration through the elimination of molecular hydrogen, and 



b. by means of an interaction with a reducible compound, i.e. an 

 acceptor molecule. 



Seven different examples of reactions of the latter type were listed 

 in which triose, lactic acid, acetaldehyde, acetyl methyl carbinol, bu- 

 tyric acid, acetone, and fructose, respectively, were reduced to the 

 corresponding products, glycerol, propionic acid, ethanol, 2,3-butyl- 

 ene glycol, butanol, iso-propanol, and mannitol, each one encount- 

 ered in some fermentation process. 



The possibility was considered that an additional dehydrogenation 

 reaction, of triose to pyruvic acid, might have to be invoked. But this 

 was not deemed necessary because the occurrence of pyruvic acid as an 

 important intermediate product had not yet been satisfactorily estab- 

 lished. Kluyver and Donker pointed out that the formation of acetal- 

 dehyde and carbon dioxide could equally well be represented by the 

 reaction sequences, 



. , / C 3 H 6 3 + 'protoplasm' -> C 3 H 4 3 -}-'protoplasm-H 2 ', a nd 



^ M C 3 H 4 3 -> CH 3 CHO + C0 2 ; or 



/ C 3 H 6 3 -> HCOOH+CH 3 CHO, and 



I HCOOH+ 'protoplasm' -> C0 2 +'protoplasm-H 2 '; 



the net result of these being obviously identical. A preference for one 

 or the other would consequently have to be based on special consider- 

 ations. Nevertheless, between the writing and proofreading of the 

 paper such arguments had apparently occurred to the authors be- 

 cause in a footnote the remark has been inserted that a continuation 

 of the study has made the earlier mentioned extension desirable. 



Various combinations of these four simple reaction types could thus 

 be used to interpret all known fermentation processes as the result of 

 specific differences in the fate of the three key intermediate products, 



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