Aminopeptidases in the serum of pregnant and nonpregnant women

According to repeated gel permeation studies the serum of nonpregnant women contained one homogeneous enzyme peak acting on n-l-leucyl-2-naphthylamine. In late pregnancy the serum displayed an additional aminopeptidase fraction with a higher molecular weight than the enzyme(s) in the nonpregnancy samples. In isoelectric focusing, the enzyme activity of the pregnancy serum appeared as several heterogeneous peaks differing in their isoelectric points from those demonstrable in the nonpregnancy samples. Further, the aminopeptidases from both of the serum sources showed differences in their affector characteristics and substrate specificity.