Peptide detection and structure determination in live cells using confocal Raman microscopy

Area of Science:

• Biophysics
• Chemical Biology
• Spectroscopy

Background:

• Peptides are crucial bioactive compounds with therapeutic potential.
• Understanding peptide interactions within cells is key to their application.
• Existing methods often lack the ability to study peptides in live cellular environments.

Purpose of the Study:

• To describe an experimental methodology for detecting and determining the structure of exogenous peptides in live cells.
• To explore peptide structure-activity relationships and metabolism directly within the cellular environment.
• To enable the study of cell-penetrating peptides in live cells.

Main Methods:

• Utilizing confocal Raman microscopy (CRM), a combination of Raman spectroscopy and confocal microscopy.
• Analyzing peptide secondary structure via amide backbone vibrations.
• Employing heavy-isotope labeling of aromatic side chains for unambiguous peptide detection.

Main Results:

• CRM provides structural information on peptides within live cells, including secondary structure and redox status.
• Aromatic ring vibrations in Raman spectra are sensitive to the peptide's cellular environment (hydrophobicity, pH).
• Heavy-isotope labeling enables clear identification and tracking of peptides inside cells.

Conclusions:

• Confocal Raman microscopy offers a powerful tool for studying exogenous peptides in live cells.
• This methodology facilitates direct investigation of peptide structure-activity relationships and metabolism.
• The technique has broad applicability for various peptide types, provided sufficient intracellular concentrations are achieved.