Fluorescence Labeling of Neurotensin(8-13) via Arginine Residues Gives Molecular Tools with High Receptor Affinity.

Fluorescence-labeled receptor ligands have emerged as valuable molecular tools, being indispensable for studying receptor-ligand interactions by fluorescence-based techniques such as high-content imaging, fluorescence microscopy, and fluorescence polarization. Through application of a new labeling strategy for peptides, a series of fluorescent neurotensin(8-13) derivatives was synthesized by attaching red-emitting fluorophores (indolinium- and pyridinium-type cyanine dyes) to carbamoylated arginine residues in neurotensin(8-13) analogues, yielding fluorescent probes with high NTSR affinity (p values: 8.15-9.