Sphingolipids are diverse lipids with sphingobases and N-acyl fatty acids as the hydrophobic moieties. While the importance of the in-depth elucidation of hydrophobic structures is widely recognized in lipid biology, mass spectrometry-based annotation of ceramides in the commonly used protonated form is often hindered by in-source dehydration during electrospray ionization in the heated state and variable water losses in the product ion spectrum. In this study, we investigated the sodium ion form and its product ions in ceramides with the use of electron-activated dissociation tandem mass spectrometry (EAD MS/MS) in addition to collision-induced dissociation to facilitate in-depth structural elucidation. While dehydrated ions from the protonated form were frequently observed, the sodium adduct ions remained stable because of their higher activation energy compared with the protonated form, which was validated using quantum chemical calculations. Using the three adduct forms under optimized conditions increased confidence in annotating the ceramide peaks through retention-time matching. Furthermore, EAD MS/MS of the sodium adduct ions facilitated the positional determination of double bonds and hydroxyl groups in the ceramide hydrophobic moiety. Our approach is showcased by the annotation of phytoceramides with N-acyl 2- and 3-hydroxyl groups in mouse feces and ceramides with N-acyl n-6 very long-chain polyunsaturated 2-hydroxy fatty acids in mouse testis.

Candida hijacks epithelial metabolism via glycolysis and GOT1-dependent TCA shunt, influencing antifungal defense.

npj Biofilms and Microbiomes - Urinary biochemical ecology reveals microbiome-metabolite interactions and metabolic markers of recurrent urinary tract infection

npj Biofilms and Microbiomes - Urinary biochemical ecology reveals microbiome-metabolite interactions and metabolic markers of recurrent urinary tract infection

eria within the bladder walls of women with rUTI. We hypothesized that increased bladder wall bacterial burden may be associated with incomplete rUTI resolution after EF. Materials and Methods: Aft...

Recurrent urinary tract infections (rUTIs) are a major clinical challenge and their increasing prevalence underscores the need to define host-microbiome interactions underlying susceptibility. How the...

Juliet Mwirigi BS’18, PhD’23, who specializes in pain studies, has been selected for a Hanna H. Gray Fellowship. Each of the 25 fellows receives up to $1.5 million in funding over eight years. After a...

Three distinguished scientists on leaving academia to advance biomedical research