ESIprot

ESIprot determines charge states and calculates molecular weights from low-resolution electrospray ionization (ESI) ion trap mass spectrometry data to enable analysis of multiply charged proteins and peptides.

Key Features:

• Charge State Determination: Determines charge states of multiply charged proteins from low-resolution ESI-MS spectra.
• Molecular Weight Calculation: Calculates molecular weights with reported absolute mass errors between -0.2 and 1.2 Da and relative errors below 30 ppm.
• Standard Deviation Optimization Algorithm: Uses standard deviation optimization (scatter minimization) to assign charge states and masses for robust spectral interpretation.
• Intensity-Independence and Minimal Peak Requirement: Operates without relying on peak intensity data and can determine charge and mass from as few as two m/z peaks when m/z quality is sufficient.
• Data Format and Platform Independence: Compatible with various raw data formats and computer platforms.

Scientific Applications:

• Proteomics: Provides charge state and mass information to support analysis of protein native conformations, folding, interactions, and post-translational modifications.
• Natural Products and Peptide Analysis: Applicable to analysis of natural products and peptides measured on low-resolution ESI ion trap mass spectrometers.

Methodology:

Applies an algorithm that minimizes scatter via standard deviation optimization on m/z values to assign charge states and calculate molecular weights without using peak intensity information, functioning with minimal peak counts (as few as two) when m/z data quality permits.