Use of MALDI-TOF mass spectrometry to reveal oxidized cardiolipin species

Abstract

Detection, identification, characterization and quantitation of oxidized cardiolipin forms in vivo is considered a challenging task, because these lipid species exist in low abundance in the biological systems. Recently it has been shown that chain-shortened products of oxidized standard phosphatidylcholines could be successfully identified by matrix-assisted laser desorption ionization (MALDI) mass spectrometry (MS) (1). Here we have characterized oxidation products of standard tetra-linoleoyl cardiolipin, such as hydroxide- and hydroperoxide-derivatives and truncated forms, by MALDI-TOF/MS analysis. In addition, by following a recently developed protocol (2), we have analysed MALDI/TOF cardiolipin fingerprints of intact leukocytes isolated from controls and aged chronic heart failure patients, in order to check for the presence of oxidized cardiolipin species. The comparison of the two sets of analyses has showed MALDI signals potentially attributable to oxidized cardiolipin species in the mass spectra of patients. In conclusion, the use of MALDI-TOF/MS analyses on intact cells or organelles might offer novel opportunities to detect oxidized lipid species in native biomembranes.