CARBOHYDRATES, FATS AND PROTEINS in 



removal of their amine groups. This can be accomplished 

 either by hydrolysis giving rise to ammonia and an hydroxy 

 acid, or by oxidation giving rise to ammonia and a ketone acid. 

 R R R 



I H 2 J0 a | 



H C OH + NH 3 ^ - H C NH 2 > C = O + NH 3 



! I -I 



COOH COOH COOH 



Hydroxy acid. Amino acid. Ketone acid. 



Although these two reactions may occur it seems probable 

 that the decomposition of amino acids gives rise to ketone 

 acids, and any hydroxy acids are formed by reduction of the 

 ketone-acids. 



In this way the nitrogen is removed and the remainder of 

 the molecule can be oxidised by the removal of the terniinal 

 carboxyl group giving rise to a fatty acid with one less carbon 

 atom. The fatty acid is then oxidised in the way described 

 above. 



That the removal of nitrogen is a reversible reaction is 

 shown by the synthesis of certain amino acids from the 

 ammonium salt of the corresponding ketone acids.* 



The removal of the carboxyl group from amino acids leaves 

 a nitrogenous base. These bases are formed in the body as 

 exemplified by the formation of /Mmidazomethyla mine from 

 histidine. 



CH NH CH NR 



|| \CH = || 



C N * C 



I I 



CH 2 CHi(NH 2 )COOH CH 2 -CH 2 NH 2 



The physiological action of these amines is of considerable 



importance. 



INTERCONVERSION OF CARBOHYDRATES, FATS AND PROTEINS 

 On looking over the previous paragraphs we see certain 

 relationships between these various classes of.compounds. Glu- 

 cose can be converted into pyruvic aldehyde. Pyruvic aldehyde 

 by the action of glyoxalase can be converted into lactic acid. 

 Alanine can be deamidised with the formation of pyruvic 

 aldehyde and pyruvic acid has been suggested as the starting 

 point for the synthesis of fats. We can express these relations 

 by the following diagramf : 



* G. Emden and E. Schmitz, Biochem. Zeit., 1900, vol. 29, p. 423. 

 t Modified from H. D. Dakin and W. H. Dudley, Journ. Biol. 

 Chem., 1913, vol 14, p. 555. 



