Reactive Brominating Species Produced by Myeloperoxidase Target the Vinyl Ether Bond of Plasmalogens: DISPARATE UTILIZATION OF SODIUM HALIDES IN THE PRODUCTION OF α-HALO FATTY ALDEHYDES

Carolyn J Albert,Jan R Crowley,Fong-Fu Hsu,Arun K Thukkani,David A Ford

doi:10.1074/jbc.m110875200

Carolyn J Albert, Jan R Crowley + Show 3 more

Open Access

https://doi.org/10.1074/jbc.m110875200

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Abstract

Plasmalogens are a phospholipid molecular subclass that are enriched in the plasma membrane of many mammalian cells. The present study demonstrates that reactive brominating species produced by myeloperoxidase, as well as activated neutrophils, attack the vinyl ether bond of plasmalogens. Reactive brominating species produced by myeloperoxidase target the vinyl ether bond of plasmalogens, resulting in the production of a neutral lipid and lysophosphatidylcholine. Gas chromatography-mass spectrometry and proton NMR analyses of this neutral lipid demonstrated that it was 2-bromohexadecanal (2-BrHDA). In comparison to myeloperoxidase-generated reactive chlorinating species, reactive brominating species attacked the plasmalogen vinyl ether bond at neutral pH. In the presence of a 20-fold molar excess of NaCl compared with NaBr, myeloperoxidase-derived reactive halogenating species favored the production of 2-BrHDA over that of 2-chlorohexadecanal. Additionally, 2-BrHDA was preferentially produced from plasmalogen treated with hypochlorous acid in the presence of NaBr. The potential physiological significance of this pathway was suggested by the demonstration that both 2-BrHDA and 2-bromooctadecanal were produced by PMA-stimulated neutrophils. Taken together, the present studies demonstrate the targeting of the vinyl ether bond of plasmalogens by the reactive brominating species produced by myeloperoxidase and by activated neutrophils, resulting in the production of novel brominated fatty aldehydes.

Highlights

Plasmalogens are a phospholipid molecular subclass that are enriched in the plasma membrane of many mammalian cells
We have recently demonstrated that plasmalogens may represent accessible molecular targets of the membrane-permeable, reactive chlorinating species generated by activated phagocytes, resulting in the production of ␣-chloro fatty aldehydes [22]
The plasmalogen vinyl ether bond is shown to be a target for reactive brominating species produced by myeloperoxidase, resulting in the production of lysophosphatidylcholine and ␣-bromo fatty aldehyde (Scheme I)

Summary

EXPERIMENTAL PROCEDURES

Materials—Bromide-free hypobromous acid was prepared as previously described [23]. The concentration of hypobromous acid was determined spectrophotometrically (⑀331 ϭ 315 MϪ1 cmϪ1) [24]. The synthetic 2-Br-[d4]-HDA was purified by HPLC utilizing a Dynamax Si column (21.4 ϫ 250 mm, 8 ␮m) and isocratic elution with hexane at a flow rate of 6 ml/min. Plasmenylcholine was synthesized by an anhydrous reaction utilizing 1-O-hexadec-1Ј-enyl-GPC and hexadecanoyl chloride as precursors with dimethylaminopyridine as a catalyst and was purified as previously described [29]. Plasmalogen Treatment with Myeloperoxidase-derived Reactive Halogenating Species: Analysis of Reaction Products by Thin Layer Chromatography and Capillary Gas Chromatography—In a typical assay 200 or 300 nmol of either lysoplasmenylcholine or plasmenylcholine was incubated in 300 ␮l of phosphate buffer supplemented with 100 mM NaBr (or selected concentrations of NaBr and/or NaCl), 20 mM NaPO4, 0.1 mM diethylenetriaminepentaacetic acid, pH 4 –7, in the presence or absence of indicated amounts of myeloperoxidase, H2O2, bromine, or hypobromous acid for indicated intervals at 37 °C.

Plasmalogen Attack by Reactive Brominating Species

RESULTS

DISCUSSION