Benzimidazole analogs of L-tryptophan were hypothesized to be inhibitors of the enzyme tryptophan indole-lyase (trpase). -(Benzimidazol-1-yl)-L-alanine, 2-amino-4-(benzimidazol-1-yl)butyric acid, and 2-amino-5-(benzimidazol-1-yl)pentanoic acid were synthesized and tested enzymatically in a tryptophan indole-lyase assay. It was determined from the conducted enzymatic studies that -(benzimidazol-1-yl)-L-alanine functioned as a substrate of trpase while 2-amino-4-(benzimidazol-1-yl)butyric acid, a homologue of -(benzimidazol-1-yl)-L-alanine, behaved as a potent inhibitor of trpase, having a Ki of 16 M. Contrastingly, 2-amino-5-(benzimidazol-1-yl)pentanoic acid was found to be trpase inactive at a concentration of 600 M. Because 2-amino-4-(benzimidazol-1-yl)butyric acid was found to function as an inhibitor of trpase, we then hypothesized that homologues of trpase substrates would likely function as inhibitors of trpase. Pursuant to the former hypothesis, 2-amino-4-(benzimidazolon-1-yl)butyric acid and S-benzyl-L-homocysteine, homologues of trpase substrates, were synthesized and it was discovered that both functioned as inhibitors of trpase. The Ki values for 2-amino-4-(benzimidazolon-1-yl)butyric acid, and S-benzyl-L-homocysteine were calculated as 15 M and 14 M correspondingly. Previous works demonstrated that inhibitors of trpase would also likely serve as inhibitors of the enzyme tryptophan synthase. -(Benzimidazol-1-yl)-L-alanine, 2-amino-4-(benzimidazol-1-yl)butyric acid, 2-amino-4-(benzimidazolon-1-yl)butyric acid, and S-benzyl-L-homocysteine were thus hypothesized as inhibitors of tryptophan synthase. Preliminary studies showed that both -(benzimidazol-1-yl)-L-alanine and 2-amino-4-(benzimidazol-1-yl)butyric acid were tryptophan synthase active; however, the Ki for these compounds was not determined. At the time of the documentation of this work, 2-amino-4-(benzimidazolon-1-yl)butyric acid, and S-benzyl-L-homocysteine had not yet been tested in the tryptophan synthase assay. S-Methyl-D-cysteine was synthesized in an effort to determine if the vasoconstriction which was observed in laboratory mice when said mice consumed S-methyl-L-cysteine, was stereospecific. Following the synthesis of S-methyl-D-cysteine our collaborators began testing S-methyl-D-cysteine in the vasoconstriction assay. The data from the vasoconstriction assay is still being collected.