Metabolism of N-Alkyl Derivatives of Amino Acids

Abstract

The metabolism of certain N-alkyl derivatives of phenylalanine, valine, leucine, and isoleucine has been studied by the methods of Rose and coworkers.1 Young white rats were fed an adequate diet containing carbohydrate, fat, inorganic salts, vitamins, and a mixture of purified amino acids. In the diets of the experimental animals the amino acid being studied was replaced by varying amounts of the corresponding N-alkyl derivatives. The growth of the rats was followed over a 28-day period.The results of these studies are shown in Table I.These data and the results of other investigators with the N-alkyl derivatives of histidine,2 tryptophane,3,4,5 methionine,6 lysine,7 and cystine8 may be summarized as follows:1. The N-methyl derivatives of the d- forms of the essential amino acids are not utilized by the white rat for growth purposes.2. With the exception of cystine the N-methyl derivative of the l- form of the amino acid has the same nutritive value as the corresponding unmethylated d- form. Thus both the...