Absorption Studies on Tryptophan and Acetyltryptophan

Many investigations have demonstrated that amino acids are absorbed by enzymatic processes (l-3).Recent investigations on the fate of ingested acetyl-L-tryptophan (4) showed that the rate of absorption of this isomer is much slower than that reported previously for an equivalent amount of free n-tryptophan (5).du Vigneaud et al. ( 6) found, however, that the acetylated analogue is utilized equally as well as the free form for growth in rats, and Baldwin and Berg (7) reported that acetyl-n-tryptophan will maintain nitrogen balance in humans.Therefore, the difference in the rate of absorption suggested that a comparison of the absorption of the various isomers of free and acetyltryptophan might help clarify the action of the enzymes concerned in this process.This paper presents experimental data on the absorption of D-, L-, DL-, acetyl-n-, acetyl-n-, or acetyl-Dn-tryptophan from the gastrointestinal tract of rats.