Phospholipase A2 activity of post-heparin plasma: A rapid and sensitive assay and partial characterization

K. M. Mohamed Shakir*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations


A simple, rapid, and sensitive assay for phospholipase A2 in post-heparin plasma that uses commercially available l-α-dipalmitoyl-(2-[1-14C]palmitoyl) phosphatidylcholine is described. The incubation mixture, containing the enzyme substrate and products, is extracted with a two-phase heptane-isopropyl alcohol-aqueous sulfuric acid system, and the labeled fatty acid in the heptane phase is separated by the absorption of unreacted substrate on silicic acid. The heptane phase, containing the labeled fatty acid, is counted after the addition of commercial liquid scintillation fluid. Phospholipase A2 activity determined by this method agrees well with the data obtained by an earlier published method. The enzyme assay is faster and more sensitive than previously published procedures and is sensitive to levels as low as 1 nmol palmitate/h/200 μl of plasma. The enzyme activity could not be found in plasma obtained prior to the injection of heparin. Plasma phospholipase A2 is thermolabile, and the enzyme activity is enhanced by 2 mm sodium deoxycholate and calcium chloride, and inhibited by EDTA.

Original languageEnglish
Pages (from-to)64-70
Number of pages7
JournalAnalytical Biochemistry
Issue number1
StatePublished - Jun 1981
Externally publishedYes


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