Linoleoyl lysophosphatidic acid and linoleoyl lysophosphatidylcholine are efficient substrates for mammalian lipoxygenases

Abstract

Oxygenation of two lysophospholipids, 1-linoleoyl lysophosphatidylcholine (linoleoyl-lysoPC) and 1-linoleoyl lysophosphatidic acid (linoleoyl-lysoPA), by reticulocyte lipoxygenase (LOX) or porcine leukocyte LOX was measured by monitoring the formation of conjugated dienes. Consistent with the above, the formation of linoleoyl-lysophospholipid hydroperoxide as oxygenation product was confirmed by LC/MS analyses. In further study, the oxygenation products of linoleoyl-lysoPC or linoleoyl-lysoPA were found to contain hydroperoxide group predominantly at C-13 with the S enantiomer as a major one, in a good agreement with the positional-specificity and stereo-selectivity of reticulocyte LOX or leukocyte LOX in oxygenation of linoleic acid. The kinetic study indicates that linoleoyl-lysoPA and linoleoyl-lysoPC are no less efficient than linoleic acid as substrates of reticulocyte LOX as well as leukocyte LOX. In contrast, these lysophospholipids were not oxygenated efficiently by potato LOX. Thus, linoleoyl-lysophospholipids such as linoleoyl-lysoPA or linoleoyl-lysoPC could be utilized as efficient substrates for some mammalian lipoxygenases.