Compounds of Formula (Ia) wherein R is a C 6 -C 12 substituted or unsubstituted aryl, a C 6 -C 12 substituted or unsubstituted heteroaryl, a C 1 -C 6 substituted or unsubstituted alkyl or -NR'R', Q is C(O), O, NR', S, S(O) 2 , C(O) 2 (CH2)p Y is C(O), O, NR', S, S(O) 2 , C(O) 2 (CH2)p Z is H or C 1 -C 4 alkyl, R' is H, C(O), S(O) 2 , C(O) 2 , a C 6 -C 12 substituted or unsubstituted aryl, a C 6 -C 12 substituted or unsubstituted heteroaryl or a C 1 -C 6 substituted or unsubstituted alkyl, when substituted, aryl, heteroaryl and alkyl are substituted with halogen, C 6 -C 12 heteroaryl, - NR'R' or COOZ, which have diagnostic and therapeutic properties, such as the treatment and management of prostate cancer and other diseases related to NAALADase inhibition. Radiolabels can be incorporated into the structure through a variety of prosthetic groups attached at the X amino acid side chain via a carbon or hetero atom linkage.
