## Poisson Model To Generate Isotope Distribution for Biomolecules

journal contribution

posted on 04.12.2017 by Rovshan G. Sadygov#### journal contribution

Any type of content formally published in an academic journal, usually following a peer-review process.

We introduce a simplified computational
algorithm for computing isotope distributions (relative abundances
and masses) of biomolecules. The algorithm is based on Poisson approximation
to binomial and multinomial distributions. It leads to a small number
of arithmetic operations to compute isotope distributions of molecules.
The approach uses three embedded loops to compute the isotope distributions,
as compared with the eight embedded loops in exact calculations. The
speed improvement is about 3-fold compared to the fast Fourier transformation-based
isotope calculations, often termed as ultrafast isotope calculation.
The approach naturally incorporates the determination of the masses
of each molecular isotopomer. It is applicable to high mass accuracy
and resolution mass spectrometry data. The application to tryptic
peptides in a UniProt protein database revealed that the mass accuracy
of the computed isotopomers is better than 1 ppm. Even better mass
accuracy (below 1 ppm) is achievable when the method is paired with
the exact calculations, which we term a hybrid approach. The algorithms
have been implemented in a freely available C/C++ code.