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Enhanced Characterization of Cardiolipins via Hybrid 193 nm Ultraviolet Photodissociation Mass Spectrometry
journal contribution
posted on 2022-02-09, 02:43 authored by Luis A. Macias, Jennifer S. BrodbeltCardiolipins
(CLs) constitute a structurally complex class of glycerophospholipids
with a unique tetraacylated structure accompanied by distinctive functional
roles. Aberrations in the composition of this lipid class have been
associated with disease states, spurring interest in the development
of new approaches to differentiate the structures of diverse CLs in
complex mixtures. The structural characterization of these complex
lipids using conventional methods, however, suffers from limited resolution
and frequently proves unable to discern subtle yet biologically significant
features such as unsaturation sites or acyl chain position assignments.
Here, we describe the synergistic use of chemical derivatization and
hybrid dissociation techniques to characterize CL from complex biological
mixtures with both double bond and sn positional
isomer resolution in a shotgun mass spectrometry strategy. Utilizing
(trimethylsilyl)diazomethane (TMSD), CL phosphate groups were methylated
to promote positive-mode ionization by the production of metal-cationized
lipids, enabling structural interrogation via hybrid higher-energy
collisional activation/ultraviolet photodissociation (HCD/UVPD). This
combination of TMSD derivatization and HCD/UVPD fragmentation results
in diagnostic product ions that permit distinction and relative quantitation
of sn-stereoisomers and the localization of double
bonds. Applying this strategy to a total lipid extract from a thyroid
carcinoma revealed a previously unreported 18:2/18:1 motif, elucidating
a structural feature unique to the lipid class.
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trimethylsilyl ) diazomethanethyroid carcinoma revealedhybrid dissociation techniquesfrequently proves unableenergy collisional activationdistinctive functional rolesdiagnostic product ionsuvpd fragmentation resultstotal lipid extractstructural feature uniquepositional isomer resolutionstructurally complex classcomplex biological mixturespreviously unreported 18complex mixtureslipid classuvpd ).structural characterizationlimited resolutionunsaturation sitesultraviolet photodissociationtmsd derivatizationsynergistic usespurring interestsn relative quantitationpromote positivepermit distinctionnew approachesmode ionizationenhanced characterizationdouble bondsdouble bonddisease stateschemical derivatizationcharacterize clcationized lipids>- stereoisomers1 motif