Nutritional studies on the Amino Acids and their Derivatives (I)

The effect of enrichment of vegetable protein with lysine and the assay of several lysine derivatives have been studied.Actual growth of and nitrogen efficiency in rats fed on the enriched diet for30 days were employed as criteria of the effect.There was observed a slight effect when the total protein content of the basal diet was less than6%, for example, when the protein source of the diet was rice powder only, even if it was enriched with 0.2% of L-lysine.When crude wheat gluten or corn protein was added to the diet so as to increase the protein content to 10%, the effect of lysine enrichment was increased remarkably, though the balance of amino acids was not changed in parallel. According to this method, lysine derivatives were assayed exactly.Enrichment with 0.2% of DL-lysine showed no effect but enrichment with 0.4% of DL-lysine was as effective as that effected with 0.2% of L-lysinye. L-lysine-L-glutamate and E-acetyl-L-lysi ne were as effective as equimolar L-lysine-HC1, but ε-benzoy1-DL-lysine exhibited no effect.Injectionof 10mg. of L-lysine twice daily (this dose is equal to enrichment of the basal diet with 0.2% of lysine) was not effective, whereas 30mg. twice daily was effective though less than enrichment with 0.2% of lysine.