Synthesis and allosteric modulation of the dopamine receptor by peptide analogs of L-prolyl-L-leucyl-glycinamide (PLG) modified in the L-proline or L-proline and L-leucine scaffolds.

Novel analogs of l-prolyl-l-leucylglycinamide (PLG) were synthesized wherein the prolyl residue was replaced with other amino acids based on a 3,5-disubstituted proline scaffold. In some examples, the l-leucyl residue was also replaced by l-valine. These analogs were tested for their ability to enhance the binding of [3H]-N-propylnorapomorphine to short isoform of human dopamine D2 receptors.