High-molecular-mass alkaline phosphatase: simplified and highly sensitive determination by liquid chromatography

This simplified HPLC method for measurement of high-molecular-mass alkaline phosphatase (high-Mr AP; EC 3.1.3.1) in serum and bile is rapid (time for column preparation and separation 30 min), reproducible (CV 4.2%), and highly sensitive (detects high-Mr AP in healthy controls at 1-3% of total AP activity in serum), and is suitable for processing small batches of sample. We characterized high-Mr AP in serum and bile by incubating samples with L-phenylalanine, neuraminidase, 1-butanol, or wheat-germ lectin, and by determining stability to heat. High-Mr AP activity was determined in sera of patients with various liver diseases (4-32% of total AP serum activity) and results were compared with those by electrophoresis on agarose.