Characterization of platelet proteins using peptide centric proteomics

Area of Science:

• Proteomics
• Analytical Chemistry
• Biochemistry

Background:

• Modern proteomics faces challenges with undersampling low-abundance, cumbersome, and hydrophobic proteins.
• Existing peptide-centric techniques generate highly complex peptide mixtures, overwhelming mass spectrometry analysis.
• High sample complexity limits the identification rates of low copy number proteins.

Purpose of the Study:

• To introduce and describe Combined Fractional Diagonal Chromatography (COFRADIC) as a solution to reduce sample complexity in proteomics.
• To highlight COFRADIC's ability to improve the analysis of complex peptide mixtures.
• To showcase the versatility of COFRADIC for various peptide subsets and modifications.

Main Methods:

• COFRADIC is a chromatography-based technique that sorts peptides based on retention time shifts after a specific modification.
• Involves an initial reversed-phase high-performance liquid chromatography (RP-HPLC) separation of peptide mixtures.
• Fractions are then modified to alter peptide retention times, followed by secondary RP-HPLC analysis.

Main Results:

• COFRADIC effectively reduces the complexity of peptide mixtures, allowing more peptides to be analyzed by mass spectrometry.
• The technique facilitates the identification of low copy number proteins by minimizing ion suppression.
• Demonstrated applicability for methionine/cysteine-containing peptides, N-terminal peptides, and other specific peptide subsets.

Conclusions:

• COFRADIC significantly enhances proteomic analysis by reducing sample complexity and improving protein identification rates.
• Its versatility allows for targeted analysis of various peptide features, including post-translational modifications.
• COFRADIC is highly automatable and suitable for analyzing large sample cohorts.