Localization of Serum Leucine Aminopeptidase Activity by Paper Electrophoresis ∗

Summary

The electrophoretic behavior of serum leucine aminopeptidase (LAP) in normal individuals, in pregnancy, and in patients with hepatobiliary disease was investigated with paper electrophoresis technics. In normal serum LAP migrated as a single component in the α₁-globulin fraction. In patients with elevated serum LAP activity due to hepatobiliary or pancreatic disease supplementary peaks of enzymatic activity were demonstrable in other protein fractions. Thus, in jaundiced patients with carcinoma of the head of the pancreas, liver metastases, biliary atresia, acute hepatitis, and drug-induced jaundice, additional activity was observed in the β-globulin fraction. In some patients with hepatitis additional activity was observed in the α₂-globulin as well as β-globulin. In common duct stone additional activity in the albumin fraction was a consistent finding. In early pregnancy the electrophoretic pattern of LAP was similar to that observed in normal serum, whereas during the third trimester LAP activity was demonstrable only in the α₂-globulin.

The valuable technical assistance of Mrs. Sally Spurling and Mrs. Thelma Alpren is acknowledged.