Rat pancreatic phospholipase A2. Purification, localization, and development of an enzyme immunoassay

Phospholipase A2 (PLA2, E.C. 3.1.1.4) was purified from rat pancreatic tissue by heat treatment of the homogenate and use of cation-exchange chromatography on a CM-Sepharose column. The enzyme was apparently homogenous on SDS polyacrylamide gel electrophoresis, and its mol wt was estimated to be 14,400. An antiserum raised against rat pancreatic PLA2 in a rabbit was used in a solid-phase enzyme immunoassay employing inorganic pyrophosphatase (E.C. 3.6.1.1) as the enzyme label. As measured by this assay, the concentration of pancreatic PLA2 in plasma was found to be above normal in rats with hemorrhagic pancreatitis induced by an intraductal injection of sodium taurocholate. PLA2 was localized in pancreatic acinar cells and in the chief cells in the mucosa of the glandular stomach by immunohistochemistry. By immunoelectron microscopy, the immunogold conjugates were mainly located on profiles of zymogen granules in acinar cells.