Synthetic peptides with selective affinity for apoptotic cells

Area of Science:

• Biochemistry
• Cell Biology
• Molecular Biology

Background:

• Anionic phosphatidylserine (PS) exposure on the plasma membrane outer leaflet signals early/intermediate apoptosis.
• Annexin V is the standard reagent for detecting cell surface PS, but alternative methods are needed for specific applications.

Purpose of the Study:

• To develop and characterize novel peptide-based reagents that can detect anionic phosphatidylserine (PS) on apoptotic cells.
• To explore zinc 2,2'-dipicolylamine (Zn2+-DPA) coordination complexes as functional mimics of annexin V for apoptosis sensing.

Main Methods:

• Synthesis of fluorescently-labelled tri- and pentapeptides incorporating Zn2+-DPA side chains.
• Assessment of selective binding of these peptides to anionic vesicle membranes.
• Utilizing fluorescein-labelled peptides for detecting apoptotic cells via fluorescence microscopy and flow cytometry.

Main Results:

• The designed peptides selectively bind to anionic vesicle membranes, indicating their ability to target PS-rich surfaces.
• Fluorescein-labelled peptide conjugates successfully detected apoptotic cells using fluorescence microscopy and flow cytometry.
• The Zn2+-DPA coordination complexes demonstrated a capacity to mimic the function of annexin V in sensing apoptosis.

Conclusions:

• Rationally designed Zn2+-DPA peptide complexes represent a viable alternative to annexin V for detecting anionic PS on apoptotic cells.
• These novel fluorescent probes offer a new tool for apoptosis research, adaptable to various detection platforms.
• The findings support the potential of coordination complexes in developing targeted molecular probes for cell biology studies.