ISOTOPICA

ISOTOPICA computes precise masses and isotopic distributions for ions containing naturally occurring isotopes from molecular formulas, peptides/proteins, DNA/RNA, and carbohydrate sequences to support interpretation of mass spectrometric data.

Key Features:

• Isotopic distribution calculation: Computes detailed isotopic distributions for a wide range of biomolecules including peptides/proteins, DNA/RNA, and carbohydrates.
• Exact mass calculation: Calculates precise mass values for ions that include naturally occurring isotopes.
• Extended molecular formula syntax: Supports modifications to input molecules using an extended molecular-formula language, accommodating common post-translational modifications.
• Resolution modeling: Models peak shapes by specifying full width at half maximum (FWHM) or a specific mass resolution.
• Mixture analysis: Determines combined isotopic envelopes for multiple overlapping distributions using user-specified relative abundances.
• Output export: Exports m/z and intensity values as plain ASCII text for downstream analysis.

Scientific Applications:

• Peptide mass fingerprinting: Aids identification of peptides by comparing observed spectra with theoretical isotopic distributions.
• Validation of isotopic distributions: Validates observed isotopic ion distributions against theoretical models, including complex multi-component samples.

Methodology:

Calculates precise masses and isotopic distributions from molecular formulas, peptide/protein, DNA/RNA, and carbohydrate inputs; applies an extended molecular-formula language for modifications; models peak widths using FWHM or specified mass resolution; combines weighted isotopic envelopes for mixtures; exports m/z and intensity as plain ASCII text.