Near-Complete Structural Characterization of Phosphatidylcholines
Using Electron Impact Excitation of Ions from Organics
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Abstract
Although
lipids are critical components of many cellular assemblies
and biological pathways, accurate descriptions of their molecular
structures remain difficult to obtain. Many benchtop characterization
methods require arduous and time-consuming procedures, and multiple
assays are required whenever a new structural feature is probed. Here,
we describe a new mass-spectrometry-based workflow for enhanced structural
lipidomics that, in a single experiment, can yield almost complete
structural information for a given glycerophospholipid (GPL) species.
This includes the lipid’s sum (Brutto) composition from the
accurate mass measured for the intact lipid ion and the characteristic
headgroup fragment, the regioisomer composition from fragment ions
unique to the sn-1 and sn-2 positions, and the positions of carbon–carbon
double bonds in the lipid acyl chains. Here, lipid ions are fragmented
using electron impact excitation of ions from organics (EIEIO)a
technique where the singly charged lipid ions are irradiated by an
electron beam, producing diagnostic product ions. We have evaluated
this methodology on various lipid standards, as well as on a biological
extract, to demonstrate this new method’s utility