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Updated: Jul 16, 2026

A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts

A Fluorescence Fluctuation Spectroscopy Assay of Protein-Protein Interactions at Cell-Cell Contacts

Published on: December 1, 2018

A simple fluorescence-spectroscopic membrane translocation assay.

Sandro Keller¹, Matthias Böthe, Michael Bienert

¹Leibniz Institute of Molecular Pharmacology FMP, Robert-Rössle-Strasse 10, 13125 Berlin, Germany. keller@fmp-berlin.de

Chembiochem : a European Journal of Chemical Biology

|March 3, 2007

Summary

This study introduces a new fluorescence-spectroscopic method to track molecules crossing lipid membranes. The method found that the cell-penetrating peptide penetratin does not cross membranes under the tested conditions.

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Last Updated: Jul 16, 2026

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Fluorescent Leakage Assay to Investigate Membrane Destabilization by Cell-Penetrating Peptide

Fluorescent Leakage Assay to Investigate Membrane Destabilization by Cell-Penetrating Peptide

Published on: December 19, 2020

Area of Science:

Biophysics
Membrane Biology
Biochemistry

Background:

Cell-penetrating peptides (CPPs) are crucial for drug delivery, but their membrane translocation mechanisms remain debated.
Conflicting data exists regarding the membrane permeability of specific CPPs like penetratin.
Accurate methods are needed to simultaneously assess membrane binding and translocation.

Purpose of the Study:

To establish and validate a novel fluorescence-spectroscopic approach for studying molecular translocation across lipid membranes.
To investigate the membrane interaction and translocation of the cell-penetrating peptide penetratin.
To resolve conflicting reports on penetratin's membrane permeability.

Main Methods:

Utilized a combination of fluorescence-spectroscopic uptake, release, and dilution experiments.
Employed intrinsic tryptophan fluorescence of penetratin for studying its interaction with phospholipid membranes.
Validated the approach using titration-calorimetry and comparison with published data.

Main Results:

Demonstrated that penetratin is not membrane-permeant under the experimental conditions used.
The fluorescence-spectroscopic method showed excellent agreement with titration-calorimetry.
The new approach allows simultaneous assessment of membrane binding and transbilayer movement without extrinsic labels.

Conclusions:

The developed fluorescence-spectroscopic method is a powerful tool for studying membrane translocation.
Penetratin does not exhibit membrane permeability under the investigated conditions.
This technique offers a label-free and simultaneous analysis of membrane binding and movement.