A fluorescent electrophile for CLIPS: self indicating TrkB binders.

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Molecular Biology

Background:

• Cyclo-organopeptides are accessible via cysteine-peptide reactions with electrophiles.
• Existing methods lack intrinsically fluorescent cyclo-organopeptides with long-wavelength emission.
• Cellular autofluorescence interferes with probes emitting at shorter wavelengths.

Purpose of the Study:

• To synthesize intrinsically fluorescent cyclo-organopeptides with robust fluorophores.
• To develop probes for studying neurotrophic factor receptor interactions.
• To enable quantifiable binding assays for surface receptors.

Main Methods:

• Synthesis of fluorescent cyclo-organopeptides via S_NAr reactions with a BODIPY system.
• Preparation of seven compounds, six with peptide sequences targeting TrkB receptors (BDNF/NT-4 loops).
• Cellular assays using HEK293 cells stably transfected with TrkB to assess cell survival and receptor binding.

Main Results:

• Successfully synthesized intrinsically fluorescent cyclo-organopeptides.
• Two of six TrkB-targeting compounds induced cell survival in HEK293 cells.
• Quantifiable binding to TrkB receptors was demonstrated (K_d ~40 and 47 nM).

Conclusions:

• Intrinsically fluorescent cyclo-organopeptides can be synthesized using BODIPY chemistry.
• These compounds can function as probes for cell survival assays.
• The probes allow for quantifiable assessment of binding to cell surface receptors like TrkB.