Characterization of serum alkaline phosphatase of hepatobiliary and osteoblastic origin.

A rapid and reproducible method for the electrophoretic separation and quantitation of serum alkaline phosphatase isoenzymes is described. Sera from patients with biopsy proven parenchymal liver diseases and diseases related to increased osteoblastic activity were subjected to electrophoresis using a continuous tris-borate buffer on a five percent polyacrylamide gel. Following electrophoresis, bands of alkaline phosphatase activity were located on the gels using a substrate of a-napthyl phosphate and a diazonium salt as activator. The stained gels were subsequently photographed, the relative mobility of each isoenzyme fraction measured and the transparencies scanned using an integrating, recording densitometer. This method coupled with heat inactiva­ tion of serum alkaline phosphatase provides a reliable indication of the tissue origin of this enzyme in patients with elevations of serum alkaline phosphatase of osteoblastic and/or hepatobiliary origin.