RelEx

RelEx converts mass spectrometry-derived peptide ion current ratios into relative protein abundances for quantitative shotgun proteomics.

Key Features:

• Least-Squares Regression: Employs least-squares regression to calculate peptide ion current ratios from mass spectrometry-derived ion chromatograms.
• Signal-to-Noise Tolerance: Handles poor signal-to-noise data to maintain quantification robustness across variable chromatogram quality.
• Automatic Data Quality Control: Automatically discards nonusable chromatograms and outlier peptide ratios to improve data quality.
• Systematic Error Correction: Applies a correction mechanism that improves quantitative accuracy by approximately 32% with a standard deviation of ±4%.

Scientific Applications:

• ICAT and Stable Isotope Labeling: Processes data from chemical tagging strategies such as ICAT and metabolic labeling with stable isotopes for relative quantification.
• High-Throughput Quantitative Proteomics: Converts large volumes of peptide ion current data into protein-level abundance estimates suitable for high-throughput studies.
• Validation and Biological Measurement: Has been validated with labeled mixtures of known molar ratios and applied to measure osmotic stress–induced protein expression changes in Saccharomyces cerevisiae.

Methodology:

Processes mass spectrometry ion chromatograms, applies least-squares regression to derive peptide ion current ratios, discards nonusable chromatograms and outlier ratios, and applies a systematic error correction that yields the reported accuracy improvement.