Bioavailability of some lysine derivatives in mice

Growth assays using mice on synthetic amino acid diets showed that substituting epsilon-N-methyl-L-lysine, epsilon-N-dimethyl-L-lysine and epsilon-N-trimethyl-L-lysine for lysine resulted in relative replacement values about 1/12, 1/20 and 1/25, respectively, of that obtained with the standard lysine diet. Similar studies showed that the alpha-N-acetyl-L-lysine is not utilized by mice and that the relative the replacement value of epsilon-N-acetyl-L-lysine was about 3% of that of lysine. Analogous substitution of D-lysine and the lysine sulfur-containing analog, S-(2-aminoethyl)-L-cysteine, for lysine resulted in weight losses during the feeding period. The results are discussed with reference to factors that are expected to influence the biological utilization f lysine analogs and derivatives.