Nitrogen Balance in Experimental Lysine Deficiency in Man.

Abstract

As part of a general study designed to determine the amino acids essential for man, the nitrogen balance was studied in 5 human volunteers who were given a diet deficient in lysine for periods of 2 to 5 weeks in length. The basic diet and the conditions of the experiment were similar to those outlined in the accompanying report1 on tryptophane deficiency. The amino acid mixture deficient in lysine was prepared by deamination of casein, a process which has been shown to destroy the biological activity of lysine;2 this was followed by acid hydrolysis, with the addition of 1.5% tryptophane (to replace that lost during hydrolysis) and of 1% cystine.Before the deficient diet was instituted the subjects were given a diet identical with the experimental diet except that an amino acid mixture containing lysine was supplied. This mixture consisted of an enzymatic hydrolysate of casein, enriched by 1% cystine. A control period on an amino acid mixture containing lysine followed the deficiency period. In subjects Es...