Spectrophotometric assay for serum platelet-activating factor acetylhydrolase activity

We developed a spectrophotometric assay for serum platelet-activating facto r acetylhydrolase (PAF-AH, EC 3.1.1.17,) activity using a platelet-activati ng factor (PAF) analogue with a 4-nitrophenyl group as substrate. PAF-AH hy drolyzes the sn-2 position of the substrate [1-myristoyl-2-(p-nitrophenylsu ccinyl)phosphatidylcholine] producing p-nitrophenyl succinate. This liberat ion was spectrophotometrically monitored and the activity determined from t he change in absorption. The assay does not require radioisotopes and is ap plicable to an automatic analyzer. Utilizing this assay with an automatic a nalyzer, it is possible to measure the activities of thousands of samples i n a few hours with excellent precision (CV 0.5%, n = 30) and high correlati on (r = 0.979, n = 100) with the results of a conventional radioisotopic as say. The assay should be particularly useful for clinical diagnostics. (C) 2000 Elsevier Science B.V. All rights reserved.