Fluorescent-labeled bioconjugates of the opioid peptides biphalin and DPDPE incorporating fluorescein–maleimide linkers. (June 2017)

• Record Type: Journal Article
• Authors: Stefanucci, Azzurra; Lei, Wei; Hruby, Victor J; Macedonio, Giorgia; Luisi, Grazia; Carradori, Simone; Streicher, John M; Mollica, Adriano
• Is Part Of: Future medicinal chemistry. Volume 9:Number 9(2017)
• Page Start: 859
• Page End: 869
• Publication Date: 2017-06
• Subjects: biphalin -- DPDPE -- fluorescein -- fluorescent probes -- GPCRs -- opioid peptides; Pharmaceutical chemistry -- Periodicals; 615.19005
• DOI: 10.4155/fmc-2016-0232
• Languages: English
• ISSNs: 1756-8919

Abstract

Aim: The conjugation of fluorescent labels to opioid peptides is an extremely challenging task, which needs to be overcome to create new classes of probes for biological assays.Materials & methods: Three opioid peptide analogs of biphalin and [D-Pen2, 5]-Enkephalin (DPDPE) containing a fluorescein–maleimide motif were synthesized.Results & discussion: The biphalin analog17 binds to opioid receptors with Ki μ = 530 ± 90 nM and Ki δ = 69.8 ± 16.4 nM. We then tested the ability of the compounds to stimulate G-protein-coupling, 17 activated μ-receptor expressing cells (EC50 = 16.7 ± 6.7 nM, EMax = 76 ± 4%) as well as δ-receptor expressing cells (EC50 = 42 ± 10 nM, EMax = 34 ± 8%). However, 17 was not able to fluorescently label receptor in live or fixed cells.Conclusion: Our data suggest that the biphalin scaffold could be employed to develop fluorescent ligands with the appropriate fluorescent motif, and suggest a means for further probe development.