Characterization of Rhodamine Conjugated Agiotensin II Peptide: Synthesis, Analysis and Receptor Binding and Internalization.

The results in this study show that the rhodamine fluorophore can be specifically conjugated to Angiotensin II at Lys3 residue (substituted for a Val) without altering the biological activity of the parent compound. The conjugated peptide was characterized using HPLC, mass spectrometry, and N-terminal sequencing. The rhodamine-Angiotensin II binds effectively to AT1 receptor and gets internalized in clathrin coated vesicles by endocytosis. These results clearly suggest the usefulness of fluorophoreconjugated peptides in studies such as, ligand-receptor binding, and ligand-receptor complex internalization, for drug delivery using cell receptors and as an alternative to peptide hormone radioimmunoassays.