A simple method to identify ether lipids in spermatozoa samples by MALDI-TOF mass spectrometry

• Published in: Analytical and bioanalytical chemistry 2013-08, Vol.405 (21), p.6675-6682
• Main Authors: Nimptsch, Ariane, Fuchs, Beate, Süß, Rosmarie, Zschörnig, Kristin, Jakop, Ulrike, Göritz, Frank, Schiller, Jürgen, Müller, Karin
• Format: Article
• Language: English
• Subjects: Acids; Aldehydes; Alzheimer's disease; Analytical Chemistry; Animals; Bioanalysis; Biochemistry; Cats; Cattle; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Deer; Desorption; Digestion; Domestic animals; Electrochemistry; Ether lipids; Ethers; Food Science; Ionization; Laboratory Medicine; Lipids; Male; Mass spectra; Mass spectrometry; Mass spectroscopy; Methods; Monitoring/Environmental Analysis; Physiology; Plasmalogens - analysis; Plasmalogens - chemistry; Properties; Research Paper; Scientific imaging; Species Specificity; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization - methods; Spectroscopy; Spermatozoa; Spermatozoa - chemistry; Sus scrofa; Tandem Mass Spectrometry - methods; Time-of-flight mass spectrometry
• ISSN: 1618-2642; 1618-2650
• DOI: 10.1007/s00216-013-7147-z

Plasmalogens (alkenylacyl glycerophospholipids) are important lipid constituents of many tissues and cells (e.g., selected spermatozoa). Since the molecular weights of plasmalogens overlap with that of diacyl- or alkyl acyl lipids, sophisticated mass spectrometry (MS; including MS/MS) analysis is normally used for the unequivocal identification of plasmalogens. We will show here that a simple matrix-assisted laser desorption/ionization time-of-flight mass spectrometer (without MS/MS capability) in combination with acidic hydrolysis and subsequent derivatization with 2,4-dinitrophenylhydrazine (DNPH) and/or digestion with phospholipase A 2 (PLA 2 ) is sufficient to determine the contributions of ether lipids in spermatozoa extracts. As neither diacyl nor alkylacyl lipids are sensitive to acids and do not react with DNPH, the comparison of the mass spectra before and after treatment with acids and/or DNPH addition readily provides unequivocal information about the plasmalogen content. Additionally, the released aldehydes are readily converted into the 2,4-dinitrophenylhydrazones and can be easily identified in the corresponding negative ion mass spectra. Finally, PLA 2 digestion is very useful in confirming the presence of plasmalogens. The suggested method was validated by analyzing roe deer, bovine, boar, and domestic cat spermatozoa extracts and comparing the results with isolated phospholipids. Figure ᅟ