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A Bimane-Based Peptide Staple for Combined Helical Induction and Fluorescent Imaging
Aimee J Horsfall1,2,3, Kylie R Dunning2,3,4, Kelly L Keeling1,3
1The Department of Chemistry, School of Physical Sciences, The University of Adelaide, North Terrace, Adelaide, SA 5005, Australia.
Chembiochem : a European Journal of Chemical Biology
|July 24, 2020
Summary
Dibromobimane effectively crosslinks peptides, creating fluorescent macrocycles. These constrained peptides reveal helical structures and can be tracked in cells using confocal imaging.
Area of Science:
- Chemical Biology
- Peptide Chemistry
- Biophysical Chemistry
Background:
- Dibromobimane is a thiol-selective fluorescent imaging agent.
- Cysteine and homocysteine residues in peptides offer sites for chemical modification.
Purpose of the Study:
- To repurpose dibromobimane for peptide macrocyclization.
- To investigate the structural impact of bimane crosslinking on short peptides.
- To evaluate the utility of bimane-tagged peptides in cellular imaging.
Main Methods:
- Macrocyclization of nine short peptides containing cysteine/homocysteine residues using dibromobimane.
- On-resin and in solution cyclization strategies were employed.
- Structural characterization using Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) spectroscopy, including Xplor-NIH calculations.
- Cellular uptake and confocal imaging studies.
Main Results:
- Successful formation of peptide macrocycles ranging from 16 to 31 atoms.
- NMR analyses revealed helical structures in specific constrained peptides (i,i+4 and i,i+3).
- Confocal imaging showed punctate cytosolic fluorescence, indicating cellular uptake and localization within endocytic vesicles.
Conclusions:
- Dibromobimane is an effective crosslinking agent for creating conformationally constrained peptide macrocycles.
- The bimane linker serves as both a structural element and a fluorescent tag.
- Bimane-tagged peptides are suitable for cell-based fluorescence imaging studies, aiding in the investigation of peptide localization and cellular interactions.
