Characterization of maternal and fetal ovine plasma cholinesterase

Abstract

Cholinesterase of maternal and fetal ovine plasma, obtained at 112–115 days of gestation, has been characterized and compared by using various techniques including statistical evaluation of kinetic parameters when using acetyl-, propionyl-, and butyrylthiocholine, gel filtration, polyacrylamide-gel electrophoresis, and sensitivity to various inhibitors. Hydrolysis of acetylthiocholine, the optimum substrate, was found to be two to three times faster in fetal plasma than in maternal plasma, although the Michaelis constants did not differ. In both maternal and fetal plasma, gel filtration yielded a major and a minor peak of cholinesterase activity, whereas electrophoresis yielded six bands of activity, including three major bands. These findings suggested quantitative rather than qualitative differences between the maternal and fetal activity. Despite the quantitative differences, there was no difference in the maternal and fetal cholinesterase sensitivity to inhibition by eserine, diisopropylfluorophosphate, and dichlorvos.