Negative ion tandem mass spectrometry of leukotriene E4 and LTE4 metabolites: Identification of LTE4 in human urine

The sulfidopeptide leukotrienes, leukotriene E 4, (LTE 4,) and its N-acetyl derivative and several \u3c9- and \u3b2-oxidized metabolites of LTE 4, have been analyzed by tandem mass spectrometry. [M-H] - ions were produced by continuous flow fast atom bombardment, and collision-induced dissociation of these ions was studied by using a triple quadrupole instrument. The product ion spectra obtained were characteristic of the structure of LTE 4, and mechanisms of ion formation were investigated by using deuterated compounds. \u3b2-Elimination of the peptide portion of LTE 4, by loss of CO 2, and ethylene amine leaves the C-l carboxyl group ionized in the most abundant fragment ion for LTE 4, and all metabolites. Tandem mass spectrometry of fast atom bombardment-generated anions from \u3c9- and \u3b2-oxidized metabolites of LTE 4, produced similar ions with only a minor influence of the third carboxyl group at the omega terminus evident. Tandem mass spectrometry was used to identify unequivocally the presence of unmodified LTE 4, in a high performance liquid chromatography-purified fraction of urine from a normal healthy volunteer after infusion with LTE 4

Analysis by fast-atom bombardment tandem mass spectrometry of phosphatidylcholine isolated from heart mitochondrial fractions: Evidence of incorporation of monohydroxylated fatty acyl moieties

Phosphatidylcholine (PC) is one of the main phospholipids present in mitochondrial membranes. According to current knowledge, the predominant fatty acyl moieties in this phospholipid are 16, 18, 20, or 22 carbon atoms long with chains that contain only carbon and hydrogen atoms. We have conducted a detailed analysis of the fatty acid substituents of the phospholipids present in mitochondrial fractions by using fast-atom bombardment tandem mass spectrometry. Six monohydroxylated C-16 and C-18 fatty acyl moieties were found in PC extracted from mitochondrial fractions of rat heart. The structure of one of these monohydroxylated fatty acids has been elucidated and corresponded to 12-hydroxy 9-octadecenoic acid. indications that concern the structure of the five other monohydroxylated fatty acids are presented. These monohydroxylated fatty acyl groups are preferentially associated in the PC molecule with C-18 and C-20 fatty acyl moieties. We present arguments to suggest that the formation of these compounds is probably not due to a free-radical initiated mechanism. The potential implication of these monohydroxylated fatty acids in several physiological functions is suggested by the fact that free hydroxylated fatty acids that are identical or closely related to those found in the mitochondrial fractions possess various biological activities