SYNTHESIS OF PHENYLALANINE AND VALINE BY HEALTHY AND URÆMIC MEN

Abstract

Nitrogen balance rapidly became negative when either or both phenylalanine and valine were withdrawn from the diet of five healthy individuals and four patients with chronic renal failure. Replacement of these " essential" aminoacids by their α-ketoacid analogues resulted in a positive or much less negative nitrogen balance in all except one man who had taken a low-protein diet for 12 years. Thus at least two of the eight aminoacids usually regarded as indispensable constituents of the diet of man can be synthesised both by healthy individuals and by some uræmic patients, provided that their diet contains the carbon skeletons of those aminoacids.