Electrophoretic patterns of alkaline phosphatase isoenzymes in human sera with abnormally high activity, and an unusual band observed in sera of patients with pancreatic cancer.

Alkaline phosphatase isoenzymes in sera were resolved by electrophoresis on cellulose acetate membranes into seven different bands (L1, B, Pl, L2, l1, l2, and Pa, in decreasing order of electrophoretic mobility). The slowest moving band (Pa) was observed in the sera of 16 patients--15 with cancer of the pancreas and one with hemochromatosis. Sera of 50 other patients with malignant or benign diseases did not show the Pa band. The Pa band is more heat labile than is the liver isoenzyme (L1). Its behavior toward inhibitors (L-phenylalanine and L-homoarginine) is similar to that of L1. Sera containing the Pa band exhibit a diffuse band in the region where isoenzymes of intestinal origin migrate; however, its heat stability and sterospecific inhibition are different from those of intestinal isoenzymes in sera that show no Pa band.