Studies on the utilization of lysinoalanine and lanthionine

Studies were conducted to determine the nutritional value of lysinoalanine for rats and chicks and the nutritional value of lanthionine for chicks. For each experiment, purified crystalline amino acid diets and crystalline lysinoalanine and lanthionine were employed. Results indicated that the lysine moiety of lysinoalanine is completely unavailable to the rat and only partially available to the chick. Of 10 rats fed lysinoalanine, seven developed nephrocytomegaly. The lanthionine studies indicated that the cysteine moiety of lanthionine is 32% available when fed as the racemic mixture and 52% available when fed as the L-DL-isomeric mixture. Thus, it appears that lysinoalanine formation in alkali-treated proteins results in a corresponding decrease in nutritionally available lysine. However, the lanthionine formed under similar conditions results in loss of only one-half of the corresponding level of nutritionally available cysteine.