134 III. OXIDATION AND METABOLISM 



ketone bodies by liver slices, Cohen^"' did not confirm this result. More- 

 over, in in vivo tests. Butts et al.^^ were unable to demonstrate any ketonuria 

 resulting from the feeding of norleucine to fasting rats. In fact, the latter 

 workers demonstrated that norleucine possesses marked ketolytic proper- 

 ties, and is a source of glycogen in the rat. The glycogenic properties of 

 this amino acid confirm the earlier results of Greenwald,^'^ who demon- 

 strated that ''extra sugar" resulted after the feeding of the racemic as well 

 as the D- and l- forms of norleucine to phlorhizinized dogs. The weight 

 of evidence would seem to indicate that norleucine is a glycogenic and not 

 a ketogenic acid. 



c'. Isoleucine: Isoleucine, CH3-CH2-CH(CH3)-CH(NH2) -COOH, has 

 properties intermediate between those of leucine and of norleucine. 

 Although Dakin'"'-' was unable to demonstrate the formation of either 

 "extra glucose" or acetone bodies when isoleucine was given to a phlo- 

 rhizinized dog, Wirth'-" did report the occurrence of ketonemia when blood 

 containing isoleucine was perfused through a surviving liver. On the 

 other hand, Butts, Blunden, and Dunn^''^ noted that the feeding of dl- 

 isoleuciiie resulted in the production of a small amount of glycogen while, 

 under certain other conditions, isoleucine served as a ketogenic acid. It 

 was suggested that, following deamination of the amino acid and the sub- 

 sequent decarboxylation, the ultimate formation of glycogen or ketone 

 bodies was dependent upon whether a demethylation or a deethylation 

 occurred on the /S-carbon atom. 



d'. Valine: The early studies of Embden et al.,'' in which liver perfusion 

 was employed, yielded no evidence that valine, (CH3)2:CH-CH(NH2) • 

 COOH, gives rise to ketone bodies. Moreover, Dakin^^^ was unable to dem- 

 onstrate any sugar formation or ketone synthesis after the feeding of valine 

 to phlorhizinized dogs. Chase and Lewis*^^ did not observe any increase in 

 liver glycogen three hours after the administration of valine. Edson^^^ 

 was the only obser\"er to report that valine was ketogenic; he tested this 

 property of valine Ijy incubating it with liver slices. Cohen^"- failed to 

 confirm the above finding, but reported instead that valine possesses an 

 antiketogenic effect. 



Later m vivo studies have apparently established the fact that vahne is 

 a glucose-former. Rose and co-workers^^^ demonstrated, by the use of the 



318 I. Greenwald, J. Biol. Chem., 25, 81-86 (1916). 



'1^ H. D. Dakin, Oxidations and Reductions in the Animal Body, 2nd ed., Longmans, 

 Green, London, 1923. 



320 J. Wirth, Biochem. Z., 27, 20-26 (1910). 



321 H. D. Dakin, J. Biol. Chem., H, 321-333 (1913). 



322 B. W. Chase and H. B. Lewis, /. Biol. Chem., 106, 315-321 (1934). 



323 W. C. Rose, J. E. Johnson, and W. J. Haines, /. Biol. Chem., U5, 679-684 (1942). 



