biostudies-literatureFreeman CNational Institute of Allergy and Infectious DiseasesNIAID NIH HHSNational Institute of General Medical SciencesNIGMS NIH HHS2376-2385https://www.ebi.ac.uk/biostudies/studies/S-EPMC10227724biostudies-literatureUnknown32(9)Up to 80% of the fatty acids in <i>Staphylococcus aureus</i> membrane lipids are branched, rather than straight-chain, fatty acids. The branched fatty acids (BCFAs) may have either an even or odd number of carbons, and the branch position may be at the penultimate carbon (<i>iso</i>) or the antepenultimate (<i>anteiso</i>) carbon of the tail. This results in two sets of isomeric fatty acid species with the same number of carbons that cannot be resolved by mass spectrometry. The isomer/isobar challenge is further complicated when the mixture of BCFAs and straight-chain fatty acids (SCFAs) are esterified into diacylated lipids such as the phosphatidylglycerol (PG) species of the <i>S. aureus</i> membrane. No conventional chromatographic method has been able to resolve diacylated lipids contaJournal of the American Society for Mass SpectrometryRevealing Fatty Acid Heterogeneity in Staphylococcal Lipids with Isotope Labeling and RPLC-IM-MS.PMC10227724R15GM0615831R21AI13535R15 GM061583K22 AI143919K22AI143919Gatto CCarpenter JMHynds HMBarbarek SFreeman CWilkinson BJHines KMBimpeh KAppala KfalseRevealing Fatty Acid Heterogeneity in Staphylococcal Lipids with Isotope Labeling and RPLC-IM-MS.Up to 80% of the fatty acids in <i>Staphylococcus aureus</i> membrane lipids are branched, rather than straight-chain, fatty acids. The branched fatty acids (BCFAs) may have either an even or odd number of carbons, and the branch position may be at the penultimate carbon (<i>iso</i>) or the antepenultimate (<i>anteiso</i>) carbon of the tail. This results in two sets of isomeric fatty acid species with the same number of carbons that cannot be resolved by mass spectrometry. The isomer/isobar challenge is further complicated when the mixture of BCFAs and straight-chain fatty acids (SCFAs) are esterified into diacylated lipids such as the phosphatidylglycerol (PG) species of the <i>S. aureus</i> membrane. No conventional chromatographic method has been able to resolve diacylated lipids conta2021-01-01T00:00:00Z2021 Sep2025-07-08T03:10:28.724Z2025-07-08T03:10:28.724ZS-EPMC102277243401466210.1021/jasms.1c00092