Enabling the Identification of Dopamine Receptor Ligands from Complex Matrices Using a Cyclic Tetrapeptide

Area of Science:

• Biochemistry
• Analytical Chemistry
• Pharmacology

Background:

• G protein-coupled receptors (GPCRs) are crucial drug targets, but identifying their ligands is challenging due to receptor instability and complex sample matrices.
• Conventional methods for GPCR ligand identification are often cumbersome and inefficient.

Purpose of the Study:

• To develop a novel, stereoselective cyclic tetrapeptide (CP1) for efficient and accurate identification of GPCR ligands.
• To overcome the limitations of traditional receptor-based methodologies in ligand discovery.

Main Methods:

• Development of a stereoselective cyclic tetrapeptide (CP1) capable of recognizing shared ligand scaffolds.
• Online coupling of CP1 with liquid chromatography for matrix complexity reduction.
• Utilizing high mass spectral resolution and predictable mass-to-charge ratio shifts for ligand identification.

Main Results:

• CP1 successfully identified dopamine (DA) receptor ligands from complex matrices.
• The first identification of beta-phenylethylamine (β-PEA), a DA receptor agonist, in underground water.
• 1-phenylguanidine (PG) and 1,3-diphenylguanidine (DPG) were identified as antagonists for dopamine receptor D1 (DRD1).

Conclusions:

• Oligopeptides, exemplified by CP1, represent a transformative class of gas-phase molecular tools for GPCR ligand discovery.
• The developed method effectively overcomes bottlenecks associated with conventional receptor-based approaches.
• The findings raise concerns regarding the potential unintended effects of identified compounds on human dopamine receptors.