Cyclic phosphatidic acid (cPA), an analog of lysophosphatidic acid (LPA), was previously identified in human serum. Although cPA possesses distinct physiological activities not elicited by LPA, its biochemical origins have scarcely been studied. In the present study, we assayed cPA formation from lysophosphatidylcholine in fetal bovine serum and found significant activity of transphosphatidylation that generated cPA. The cPA-producing enzyme was purified from fetal bovine serum using five chromatographic steps yielding a 100-kDa protein with cPA biosynthetic activity. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of its tryptic peptides revealed that the enzyme shared identical fragments with human autotaxin, a serum lysophospholipase D that produces LPA. Western blot analysis demonstrated that the 100-kDa protein was specifically recognized by an anti-human autotaxin antibody. Moreover, recombinant rat autotaxin was found to generate cPA in addition to LPA. No significant cPA-or LPA-producing activity was detected in autotaxin-depleted serum from bovine or human prepared by immunoprecipitation with an anti-autotaxin monoclonal antibody. These results indicate that the generation of cPA and LPA in serum is mainly attributed to autotaxin.

Contact of fabric surfaces with human skin inevitably results in transfer of human sebum, which cannot be easily removed by washing the fabrics in water with conventional detergents (1). Sebum, the sebaceous secretion of the skin, consists of a complex mixture of triglycerides, squalene, cholesterol and other sterols, free fatty acids and aliphatic hydrocarbons (2) and is the major oily soil constituent in home laundry. Although many studies on the removal of sebum soil from different substrates have been reported, few address the thermodynamics of sebum soil removal from fiber substrates into aqueous surfactant solutions. The mechanism for removal of oily soil by a substratewater-micelle system can be considered a two-step process involving the transfer of soil from substrate to water (non-micellar phase) and then from water into micelles. Thus, the free energy change of soil determines whether a detergent process will be successful in removing the 167 JOS