A Fluorescent-Based Assay for Measurement of Phospholipase A2 Activity: A Facile Assay for Cell Sonicates

Phospholipases A₂ (PLA₂ ) catalyze the hydrolysis of the ester bond at the sn-2 position of phospholipids to generate the lysophospholipid and free fatty acid (1 ). Several classes of PLA₂ s have been identified (2 ). They include the low molecular weight-secreted enzymes, which demonstrate a requirement for millimolar concentrations of Ca²⁺ for full activity and are generally involved in the inflammatory response. The high molecular-weight, cytosolic PLA₂ s are activated by submicromolar calcium, have specificity for unsaturated fatty acids and arachidonic acid in particular (3 ,4 ). The arachidonic acid released can have many direct functions or can serve as a precursor in the formation of the numerous prostaglandin and leukotriene products (5 ). Thus, it is becoming increasingly clear that this latter class of enzymes are the principle regulators of arachidonic-acid release and therefore play an important role in signal transduction (6 ).