Isoenzymes of Serum Alkaline Phosphatase in Hepatobiliary and Skeletal Disease

Abstract

The techniques of vertical starch gel electrophoresis and incubation of the gel in a Tris-maleate buffer mixture containing sodium-alpha-naphthyl phosphate and 4-amino-diphenylamine-diazonium sulfate have been utilized to separate and localize multiple isoenzymes of serum alkaline phosphatase (AP). 202 serum samples were obtained from normal hospital personnel and patients with a variety of diseases associated with elevated serum AP. Eight zones of AP activity were found and named with reference to corresponding serum proteins: fast alpha (Foc), beta ([beta]), alpha beta ([alpha] [beta]) and alpha (alpha-1, alpha-2, alpha-3) globulins; beta-lipoprotein ([beta]L) and origin (O). These zones were arranged in 3 patterns. One pattern was associated with obstructive, metastatic or infiltrative hepatobiliary disease ([beta],[beta]L and O-AP); a 2nd pattern was seen with parenchymal liver disease ([beta] and [beta]L-AP); the 3rd pattern was characteristic of increased osteoblastic activity (alpha[beta] and [beta]L-AP). It was also suggested that alpha[beta]-AP may arise in bone, [beta]-AP in an extra-hepatic source as small bowel mucosa and O-AP (primarily 5-nucleotidase) in the hepatic parenchymal cell.