CHAPTER VI 



* 



THE FURTHER FATE OF AMINO ACIDS 



It is well recognized that a large part of the aminp 

 acids of the food is eliminated from the body in the 

 form of urea, carbon dioxide, and water. The various 

 amino acids presumably undergo a variety of chemical 

 changes previous to their excretion as the simple pro- 

 ducts mentioned above. Also the ease with which these 

 transformations take place is different for the indi- 

 vidual amino acids. The steps leading to the ultimate 

 fate of some are quite clear, of others it is very ob- 

 scure or entirely unknown. The unlike ease of trans- 

 formation of amino acids into urea has been shown 

 by intravenous injection. Thus glycocoll and leucine 

 yield urea more or less completely whereas alanine, 

 cystine, aspartic and glutamic acids are not readily 

 catabolized. 



In general the first step in the metabolism of amino 

 acids is that of oxidativg__dfiamination a splitting off 

 of ammonia with aft accompanying oxidation. For 

 any straight chain amino acid the reaction 'occurring 

 may be represented as follows r 



R.CH 2 .CH.NH 2 .COOH + Q-= 



R.CH,.COOH + C0 a + NH, 

 



