Purification and characterization of human pancreatic phospholipase A2

We purified human pancreatic phospholipase A2 from postmortem pancreatic tissue by elution of the semi-purified enzyme on CM-Sephadex C-25 with a linear NaCl gradient at pH 6.0. The enzyme appeared as a single polypeptide chain with an isoelectric point of 9.2 +/- 0.1. The relative molecular mass of the enzyme was estimated to be 15 800 +/- 1000 by sodium dodecyl sulfate/polyacrylamide gel electrophoresis. The enzyme is resistant to heating and to a 25 g/L concentration of sodium dodecyl sulfate. It is inhibited by Ca2+ ions in the presence of ovolecithin and deoxycholate. By immunohistochemical methods we showed the enzyme to be localized in the apical zymogen granule portion of pancreatic acinar cells.