Detection of native proteins using solid-substrate electrospray ionization mass spectrometry with nonpolar solvents

Area of Science:

• Analytical Chemistry
• Biochemistry
• Proteomics

Background:

• Direct detection of native proteins from raw biological samples using mass spectrometry is challenging.
• Existing methods often require extensive sample preparation, limiting throughput and potentially altering protein structure.

Purpose of the Study:

• To develop and demonstrate a mass spectrometry technique for direct native protein detection from raw biological samples.
• To elucidate the mechanism behind the novel ionization process.

Main Methods:

• Solid-substrate electrospray ionization mass spectrometry (SS-ESI-MS) utilizing nonpolar solvents (e.g., n-hexane).
• Analysis of various raw biological samples, including viscous (egg white) and solid (bone marrow) matrices.
• Mechanistic investigation of the ionization process.

Main Results:

• Successful direct detection of native proteins and protein complexes from raw biological samples.
• The technique functions by rapid nonpolar solvent vaporization, surface cooling, ambient water condensation, and subsequent electrospray ionization.
• Effective analysis of challenging viscous and solid samples was achieved.

Conclusions:

• Solid-substrate electrospray ionization with nonpolar solvents offers a direct and efficient method for native protein analysis.
• The findings provide new insights into mass spectrometry sampling and ionization mechanisms.
• This technique holds significant potential for advancing protein characterization in complex biological systems.