Placental and non-placental leucine aminopeptidases during normal pregnancy.

1. A simple and rapid method discriminating between placental and non-placental leucine aminopeptidases (LAP) existing in pregnancy serum is described, which includes technics of heat inactivation at 60 degrees for 30 minutes and inhibition by 0.02 M L-methionine. 2. Serial determinations of serum total, heat-stable and L-methionine-insensitive LAP activities during normal pregnancy were carried out. 3. The results were ascertained by disc electrophoresis and it was found that the heat-stable enzyme corresponds to normal serum LAP; the L-methionine-insensitive enzyme to pregnancy serum LAP of placental origin; the sum of these two to total serum LAP.