A series of 2-(thioalkyl) pentanedioic acids were synthesized and evaluated as inhibitors of glutamate carboxypeptidase II (GCP II, EC 3.4. 17.21). The inhibitory potency of these thiol- based compounds against GCP II was found to be dependent on the number of methylene units between the thiol group and pentanedioic acid. A comparison of the SAR of the thiol- based inhibitors to that of the phosphonate-based inhibitors provides insight into the role ...