182 III. OXIDATION AND METABOLISM 



+ CO2, is to some extent reversible. Under certain conditions, the 

 fixation of a small amount of carbon dioxide can occur in the acetone mole- 

 cule, with the resultant formation of acetoacetate. Coon®"^ also proved 

 that a similar fixation of carbon can take place to a large extent on the iso- 

 propyl alcohol fragment formed on the breakdown of leucine or isovaleric 

 acid. This author indicates that a similar reaction may occur with acetone, 

 but that this reaction is only a minor one. 



Price and Rittenberg ^"^ observed that acetone can be largely oxidized 

 to CO2 and exhaled in the respiratory air within twenty-four hours after 

 the feeding of 1,3-C^^-acetone to rats. When the C ^^-methyl-labeled 

 acetone was given in small doses (0.1 to 0.6 mg./lOO g. body weight) to 

 rats by stomach tube, less than 10% was found to be exhaled as such. 

 At least half of the ketone was oxidized and the C^^02 excreted within 

 twenty-four hours. Oxidation of acetone was likewise found to occur in 

 alloxan-diabetic rats.^°* Polonovski and Valdiguie^"^ suggest that the 

 oxidation of acetone may occur via the tricarboxylic acid cycle. 



A number of workers have noted that labeled carbon atoms of acetone 

 may appear in cholesteroP^^'^o®'*''^ as well as in fatty acids.^"*'^"^ It is 

 generally believed that the acetyl group is formed as an intermediate in 

 these syntheses.^"* ■^"^■^"'^ According to Sakami, working alone^"^ and with 

 Lafaye,^"^ acetone is split to yield a one-carbon and a two-carbon fragment 

 which correspond to formate and acetate. Since carbonyl-labeled acetone 

 was found to be converted into glycogen, it is believed that a third product 

 of oxidation may be the unsplit 3-carbon acid identical with or similar 

 to pyruvic acid.^*^^ Price and Rittenberg^" ^ also reported that acetone 

 contributes carbon atoms to urea, arginine, aspartic and glutamic acids, 

 liver glycogen and also liver and carcass cholesterol and carcass fatty 

 acids. Wood and co-workers*^" '^^^ have found that Clostridium aceto- 

 butylicum (anaerobe from corn, potato, molasses, and soil) and CI. hutijlicum 

 (anaerobe producing butylic acid) ferment butyl alcohol, and change 

 acetone to isopropyl alcohol. It is therefore evident that acetone is not 



eos M. J. Coon, /. Biol. Chem., 187, 71-82 (1950). 



8°^ I. D. Price and D. Rittenberg, /. Biol. Chem., 185, 449-459 (1950). 



««» M. Polonovski and P. Valdiguie, Compt. rend., 224, 1531-1533 (1947). 



«« E. Borek and D. Rittenberg, /. Biol. Chem., 179, 843-845 (1949). 



<»' I. Zabin and K. Bloch, /. Biol. Chem., 185, 131-138 (1950). 



««8 W. Sakami, /. Biol. Chem., 187, 369-378 (1950). 



•W9 W. Sakami and J. M. Lafaye, ./. Biol. Chem., 193, 199-203 (1951). 



"" H. G. Wood, R. W. Brown, C. H. Werkman, and C. G. Stuckwisch, J. Am. Chem. 

 Soc, 66, 1812-1818 (1944). 



611 H. G. Wood, R. W. Brown, and C. H. Werkman, Arch. Biochem., 6, 1812-1818 

 (1944). 



