438 ACETONE BODIES 



The fact of the matter is that leucin is recognized as 

 capable of serving in the economy as a source of acetone 

 bodies. As long as it was known only that acetone could 

 be produced from it by perfusion through the liver it could 

 be supposed that this occurred by the separation of the leucin 

 nucleus at the position of branching and the entrance of an 

 atom of oxygen at this point : 

 CH, CH 3 



CH CH 3 CH 3 



CH 2 > CO 



CH.NH, 



COOH 



precisely as we suppose that acetone is formed in oxidation 

 of proteins with peroxide of hydrogen (Vol. I of this series, 

 p. 23, Chemistry of the Tissues). This view, however, 

 was seen to be incorrect after it was recognized that diacetic 

 acid in this case also serves as a forerunner of acetone. It is 



CH \ 



now held that isoamylamine, ' >CH CH, CH,.NH 2 , isovaler- 



aldeyde, /CH CHz COH, and isovalerianic acid, 



CHj/ 



>CH CHr-COOH, can contribute to the formation of 

 CH,/ 



acetone bodies in the economy, as well as ethylbutyric acid, 



CH,\ _ 



CHr-COOH, /?-oxyisovaleriamc acid, 



COOH, dimethylacrylic acid, C = CH COOH, and crotonie 



acid, CH 3 CH=CH COOH. In the first mentioned instances a 

 possible arrangement might be made by which one of the 

 alkyl groups above the position of branching is thrown off 

 and replaced by a hydroxyl radicle : 



AlJLJ V-'i. 



V 



CHj CHj CH| 



CH.OH 



CH, CH, 



COOH COOH. 



