246 



E. S. GUZMAN BARRON, F. GHIRETTI 



VOL. 12 (1953) 



TABLE VIII 



CITRIC AND SUCCINIC ACIDS FORMED IN BAKER's YEAST 

 DURING THE OXIDATION OF ACETATE 



Buffer, o.iM phthalate pH 4.0, 10 ml; yeast suspended in water, 10 ml (46.6 mgs) ; 2.5 ml of 

 acetate, 0.2M ; 2.5 ml of malonate, o.iM; i.o ml. KOH, 3N. Time, 180 minutes. Temp. 38^. 



Determinations 



Acetate 

 c.mm. 



Acetate + Malonate 

 c.mm. 



O2 uptake 



Citrate 



Succinate 



4166 

 43-8 

 10 



900 



11.7 

 164 



paper chromatograms only succinic acid was found. In all these experiments iml of 

 iN H2SO4 was added to the Warburg vessels at the end of the incubation period; the 

 samples were boiled for a few minutes, and after centrifugation the solutions were 

 extracted with ether for 24 hours in the Kutscher-Steudel extractors. Malonate was 

 previously oxidized with permanganate. 



The anaerobic oxidation of acetate. Cell-free extracts of Corynebacterium creatinovorans 

 were found to oxidize acetate anaerobically, as shown by the reduction of methylene 

 blue^. This anaerobic oxidation was attributed to the oxidative condensation to succinate 

 because on oxidation of acetate in the presence of malonate there was accumulation of 

 succinate and no citrate formation. Similar cell-free extracts prepared from 24-hour 

 cultures of A. aerogenes, after 24 hours dialysis at 3° against 0.154.!/ KCl, failed to re- 

 duce meth3dene blue on addition of acetate, unless the following components were added : 

 Coenzyme A, DPN, FAD, and MgCU (Table IX). Omission of any one of these compo- 



TABLE IX 



ANAEROBIC OXIDATION OF ACETATE BY DIALYZED CELL-FREE EXTRACTS 

 OF AEROBACTER AEROGENES (24 HOURS CULTURE) 



nents inhibited dye reduction. Furthermore, it was found that addition of-SH reagents, 

 such as iodosobenzoate or j6-Cl-Hg benzoate also produced inhibition. Whether this 

 inhibition is due to combination with the-SH group of coenzyme A or with thc-SH 

 groups of the protein is not known. DPN was reduced at very slow rate in extracts from 

 C. creatinovorans. Anaerobic oxidation of acetate in the presence of the components 

 above mentioned has also been found in cell-free extracts of baker's yeast, Pseudomonas 

 fluorescens, Aspergillus, and Tetrahymena geleii. It seems that this enzyme, which may 

 be called acetic dehydrogenase, is present not only in those cells which were believed to 



References p. 24g. 



