Purification and characterization of human pancreatic phospholipase A2 and development of a radioimmunoassay.

Human pancreatic phospholipase A2 was purified to homogeneity from pancreatic juice and a reliable radioimmunoassay for the enzyme was developed. The molecular weight of the enzyme as estimated by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 14,000. Phosphatidylcholine was hydrolyzed well in an alkaline pH range, and the optimum activity was obtained at pH 9. Calcium ion was indispensable for activity. The enzyme was stable to heat treatment at 60 degrees C for 5 min. The radioimmunoassay system was highly sensitive, reproducible and specific. The dilution curves for the sera of patients with acute pancreatitis were parallel to the standard curve. In healthy individuals, serum phospholipase A2 concentrations ranged from 2.0 to 7.9 ng/ml, the average being 5.1 ng/ml (S.D.: 1.7). In patients with acute pancreatitis, significant elevations of serum phospholipase A2 contents were observed, and the highest value found was 4,000 ng/ml.