Cystine animopeptidase and leucine aminopeptidase of choriocarcinoma cells grown in culture.

Cystine animopeptidase (CAP) and leucine aminopeptidase (LAP) in choriocarcinoma cells grown in culture were assayed and characterized electrophoretically. The specific activity of CAP in choriocarcinoma was about 1.5-fold greater than the specific activity of term placenta. The extract of choriocarcinoma contained an enzyme which is similar to one of the pregnancy-specific serum aminopeptidases in electrophoretic mobility and in resistance to inhibition by 0.1M methionine. The CAP activity was not increased in either the cells or the medium by growing the cells in the presence of oxytocin, estrogen, progesterone, or prostaglandin F-2alpha. It was tentatively concluded that choriocarcinoma cells produce CAP and that it is not regulated by any of these hormones.