Raman detection of proteomic analytes

Area of Science:

• Analytical Chemistry
• Biochemistry
• Spectroscopy

Background:

• Proteomics often relies on techniques like chromatography and mass spectrometry.
• Integrating non-destructive methods like Raman spectroscopy can enhance proteomic workflows.
• Current Raman spectroscopy methods may face limitations in sensitivity and compatibility with complex biological samples.

Purpose of the Study:

• To demonstrate the compatibility of non-enhanced Raman spectroscopy with chromatographic and mass spectroscopic proteomic sensing.
• To establish a sensitive and non-destructive method for protein analysis.
• To showcase the utility of the drop coating deposition Raman (DCDR) method in proteomics.

Main Methods:

• Development and application of the drop coating deposition Raman (DCDR) method.
• Microdeposition of protein solutions onto a substrate, followed by solvent evaporation.
• Backscattering detection of normal Raman spectra.
• Integration with High-Performance Liquid Chromatography (HPLC) and Matrix-Assisted Laser Desorption/Ionization-Time of Flight (MALDI-TOF) mass spectrometry.

Main Results:

• High-quality normal Raman spectra obtained from protein solutions at concentrations as low as 1 microM (1 fmol of protein).
• Non-destructive probing of proteins within the excitation laser beam.
• Successful detection of insulin from an HPLC fraction.
• Non-destructive DCDR followed by MALDI-TOF analysis of lysozyme.
• Detection of protein spots deposited via an ink-jet microprinter.
• Identification of spectral differences between glycan isomers, relevant for post-translationally modified proteins.

Conclusions:

• Non-enhanced Raman spectroscopy is compatible with established proteomic techniques.
• The DCDR method offers a sensitive, non-destructive approach for protein analysis.
• This integrated approach has broad applications in proteomics, including the analysis of post-translationally modified proteins.