How Many proteins are Missed in Quantitative proteomics Based on Ms/Ms sequencing Methods?

Area of Science:

• Proteomics
• Biochemistry
• Cancer Research

Background:

• Quantitative proteomics relies on MS/MS sequencing of peptides.
• Sample preparation is a critical factor influencing method performance.
• Current limitations hinder comprehensive proteome coverage.

Purpose of the Study:

• To evaluate the effectiveness of different protein pre-fractionation strategies.
• To improve the number of identified proteins and spectral counts in quantitative proteomics.
• To compare pre-fractionation based on pI and MW versus MW alone.

Main Methods:

• Utilized cytosolic proteins from MCF-7 breast cancer cells.
• Employed bottom-up quantitative proteomics with MS/MS sequencing.
• Applied pre-fractionation techniques based on isoelectric point (pI) and molecular weight (MW).

Main Results:

• Pre-fractionation by pI and MW identified more proteins (947) than MW alone (704).
• Combining data from different pre-fractionation methods identified 1238 proteins.
• Increased spectral counts per protein were observed with effective pre-fractionation.

Conclusions:

• Protein pre-fractionation is crucial for enhancing proteome coverage in quantitative proteomics.
• Peptide overlap and limited sequencing throughput, not MS sensitivity, are current bottlenecks.
• Internally calibrated methods (SILAC, ICAT, ITRAQ) may offer better proteome coverage than spectral counting.