Purification of Platelet-Activating Factor Acetylhydrolase
The only known phospholipid with potent biologic activity, Platelet-activating Factor (PAF, PAF-Acether), has been identified as 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine (1-alkyl-2-acetyl-GPC).1 Among the diverse effects of PAF are the activation of platelets, neutrophils and monocytes, and the induction of thrombocytopenia, neutropenia, hypotension and vasopermeability in whole animals. The biologic activity of PAF depends upon the presence of a short chain acyl group at the sn-2 position, and hydrolysis of this ester destroys bioactivity. This reaction is catalyzed by a plasma component that was originally described as “acid-labile factor”2, but now has been identified as PAF-acetylhydrolase. We find that this activity is responsible for nearly all of the initial metabolism of PAF in whole blood, and have partially purified and characterized this activity.
KeywordsCritical Micellar Concentration Lipoprotein Particle Potent Biologic Activity High Molecular Weight Aggregate Lipid Interface
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- 2.R.N. Pickard, R. Farr and D.J. Hanahan, Physiochemical and functional identity of rabbit platelet-activating factor (PAF) released in vivo during IgE anaphylaxis with PAF released in vitro from IgE-sensitized basophils, J. Immunol. 123: 1847 (1979).Google Scholar