UTILISATION OF KETOACID ANALOGUES OF VALINE AND PHENYLALANINE IN HEALTH AND URÆMIA

Abstract

¹⁵N-labelled ammonium chloride was given to four healthy individuals and to two uræmic patients during studies of the ability of α-ketoisovaleric and β-phenylpyruvic acid to substitute for valine and phenylalanine. ¹⁵N enrichment of valine, phenylalanine, and other essential and non-essential aminoacids is reported, In three of the four healthy individuals the incorporation of ¹⁵N into the appropriate essential aminoacid increased. No significant uptake of ¹⁵N was found in the fourth individual. One uræmic patient showed a much greater enrichment of phenylalanine and valine than did healthy individuals. Her uptake of ¹⁵N was also much greater than the uptake by the other and more uræmic patient who had failed to maintain nitrogen balance with the ketoacids. It is concluded from these isotopic studies that a number of healthy and uræmic men can synthesise phenylalanine and valine from their ketoacid analogues.