TRIGLYCERIDES AND PATTY ACIDS 79 



oxidized by the kidney fatty acid-oxidizing system. When isocaproate was 

 oxidized, isobutyric acid could be separated from the reaction mixture. 

 These demonstrations constitute the most convincing proof of the ^- 

 oxidation theory yet obtained, since they involve the actual separation 

 and identification of the reaction product of the oxidation of an odd-chain 

 acid and a branched-chain acid. 



Finally, Deuel et al.^^ noted that glycogen synthesis is of a considerably 

 higher order when the triglycerides of fatty acids with an odd number of 

 carbons are fed than when the triglycerides of the even-chain acids of cor- 

 responding length are given. One can only conclude that the behavior of 

 the odd-chain and that of the even-chain fatty acids differ so much as to 

 preclude a change of one to the other during their catabolism. Therefore, 

 the metabolism of both the even-chain and the odd-chain fatty acids must 

 involve a removal of fragments of two carbons, or, at least, of an even 

 number of carbon atoms, at a time. 



In addition to the formation of ketone bodies from fatty acids as a result 

 of metabolism in the intact animal, the many experiments with isolated 

 tissues support the /3-oxidation theory. Thus, Jowett and QuasteP^'^^ 

 reported that an extensive ketone body formation occurred when liver 

 slices were mcubated with butyric, caproic, or caprylic acids ; on the other 

 hand, only a slight ketone body synthesis followed incubation with valeric, 

 heptanoic, or nonanoic acids. Munoz and Leloir^*'^^ likewise published 

 papers dealing with the quantitative aspects of ketone body production by 

 Uver slices when different fatty acids were added to the substrate. Simi- 

 lar variations in ketone body production by the liver slices when even- 

 chain or odd-chain fatty acids were employed as substrates have been re- 

 ported by Witter, Cottone, and Stotz.^^ 



Added support for the /3-oxidation hypothesis is to be obtained from the 

 proof that the main end-product, acetic acid, is capable of oxidation in the 

 tissues. Thus, Pardee, Heidelberger, and Potter'*^ reported that acetate- 

 l-C* was oxidized by slices and homogenates of rat tissues in vitro. Oxalo- 



" H. J. Deuel, Jr., J. S. Butts, H. Blunden, C. H. Cutler, and L. Knott, J. Biol. 

 Chem., 117, 119-129 (1937). 



" M. Jowett and J. H. Quastel, Biochem. J., 29, 2159-2180 (1935). 



" M. Jowett and J. H. Quastel, Biochem. J., 29, 2181-2191 (1935). 



" L. F. Leloir and J. M. Munoz, Biochem. J., 33, 734-746 (1939). 



« J. M. Munoz and L. F. Leloir, J. Biol. Chem., U7, 355-362 (1943); 163, 53-59 

 (1944). 



«> R. F. Witter, M. A. Cottone, and E. Stotz, J. Biol. Chem., 207, 671-678 (1954). 



"' A. B. Pardee, C. Heidelberger, and V. R. Potter, J. Biol. Chem., 186, 625-635 

 (1950). 



