High-molecular-mass alkaline phosphatase in amniotic fluid: properties and relationship with lamellar body...

We have confirmed that most of third trimester amniotic fluid alkaline phosphatase is macromolecular. This is not, however, as has been previously suggested, due to complexing with lamellar body phospholipid. Amniotic fluid high-Mr ALP and serum high-Mr ALP are similar with regard to p-nitrophenylphosphate hydrolysis, thermostability, and activation energy but experiments with uncompetitive inhibitors indicate differences in isoenzyme composition.