New algorithm for 15N/14N quantitation with LC-ESI-MS using an LTQ-FT mass spectrometer

Area of Science:

• Proteomics
• Analytical Chemistry
• Bioinformatics

Background:

• Accurate quantitation of relative protein abundances is crucial for understanding complex biological systems.
• Existing methods for proteomic quantitation face challenges in accuracy, throughput, and data processing.

Purpose of the Study:

• To introduce a novel algorithm, Quantitative Proteomics (QN), for the (15)N/(14)N quantitation of relative protein abundances.
• To leverage the capabilities of the LTQ-FT MS hybrid mass spectrometer for enhanced proteomic analysis.

Main Methods:

• QN utilizes high resolution, mass accuracy, and throughput of the LTQ-FT MS.
• Peptide quantitation is based on MS peak intensity (FT MS), and identification is performed in MS/MS mode (LTQ linear ion trap).
• A novel scoring procedure enhances accuracy by filtering unreliable peptide abundance measurements.

Main Results:

• QN was applied to analyze M. acetivorans C2A cultures, quantifying approximately 1,000 proteins.
• The average coefficient of variation (CV) for protein abundance ratios was 9%.
• The algorithm performs quantitation without manual intervention and requires minimal processing power.

Conclusions:

• QN provides an accurate and reliable method for relative protein quantitation in complex proteomic samples.
• The algorithm is automated, efficient, and generates data compliant with proteomic data publication standards.
• QN enhances the reliability of proteomic data analysis through a novel scoring and filtering approach.