Lipid Species Annotation at Double Bond Position Level with Custom Databases by Extension of the MZmine 2 Open-Source Software Package

In
recent years, proprietary and open-source bioinformatics software
tools have been developed for the identification of lipids in complex
biological samples based on high-resolution mass spectrometry data.
These existent software tools often rely on publicly available lipid
databases, such as LIPID MAPS, which, in some cases, only contain
a limited number of lipid species for a specific lipid class. Other
software solutions implement their own lipid species databases, which
are often confined regarding implemented lipid classes, such as phospholipids.
To address these drawbacks, we provide an extension of the widely
used open-source metabolomics software MZmine 2, which enables the
annotation of detected chromatographic features as lipid species.
The extension is designed for straightforward generation of a custom
database for selected lipid classes. Furthermore, each lipid’s
sum formula of the created database can be rapidly modified to search
for derivatization products, oxidation products, in-source fragments,
or adducts. The versatility will be exemplified by a liquid chromatography–high
resolution mass spectrometry data set with postcolumn Paternò–Büchi
derivatization. The derivatization reaction was performed to pinpoint
the double bond positions in diacylglyceryltrimethylhomoserine lipid
species in a lipid extract of a green algae (Chlamydomonas
reinhardtii) sample. The developed Lipid Search module extension
of MZmine 2 supports the identification of lipids as far as double
bond position level.