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Regional phospholipid analysis of porcine lens membranes by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Author(s) -
Estrada Rosendo,
Yappert M. Cecilia
Publication year - 2004
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.759
Subject(s) - chemistry , phosphatidylethanolamine , phospholipid , sphingomyelin , chromatography , mass spectrometry , membrane , matrix assisted laser desorption/ionization , degree of unsaturation , mass spectrum , analytical chemistry (journal) , ionization , ion , quantitative analysis (chemistry) , phosphatidylcholine , desorption , biochemistry , organic chemistry , adsorption
The applicability of matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) to the qualitative and quantitative analysis of most mammalian phospholipid (PL) classes was demonstrated in a crude extract of porcine lens membranes. When 2,5‐dihydroxybenzoic acid (DHB) was used as the matrix, positive‐ion spectra allowed the accurate quantification of phosphatidylcholines (PCs) and sphingomyelins (SMs). Other PLs such as phosphatidylethanolamines (PEs), phosphatidylethanolamine plasmalogens (PEps), phosphatidylethanolamine ethers (PEes) and phosphatidylserines (PSs), could also be detected, but their lower ionization efficiency led to negative errors in their quantification. Despite this limitation, it was possible to determine relative changes among PLs extracted from cortical and nuclear regions. Negative‐ion spectra were acquired with the use of p ‐nitroaniline (PNA) as the matrix. Because neither PCs nor SMs produce negative ions, other PL classes can be analyzed selectively. The absolute quantification of the various PL classes detectable in negative‐ion spectra was also affected by differences in ionization efficiencies. However, the trends in compositional changes between cortical and nuclear‐fiber PLs were in agreement with those obtained by 31 P NMR spectroscopy. MALDI‐TOFMS also offers the possibility of studying variations in the acyl‐chain distribution of the various species comprising each PL class. For porcine lenses, PCs, PEs and phosphatidylinositols (PIs) exhibited the greatest depletions in going from cortical to nuclear membranes. Among their individual species, those with two or more sites of unsaturation suffered the most significant reduction. Copyright © 2004 John Wiley & Sons, Ltd.