Immunoaffinity Purification of Human Choline Acetyltransferase: Comparison of the Brain and Placental Enzymes

Abstract

A rapid and efficient immunoaffinity purification procedure was developed for human placental choline acetyltransferase (ChAT). Using this procedure, human placental ChAT was purified to homogeneity with high recovery of enzyme activity (50-60%). Purified ChAT was used to raise a monospecific anti-human ChAT polyclonal antibody in rabbits. A comparison of the physical properties of ChAT was made between the enzymes purified from human brain and human placenta. Only 1 form of the enzyme exists in either tissue, having identical MW of 68,000 and a single apparent pI [isoelectric point] of 8.1. A more detailed comparison of the 2 enzymes using peptide mapping and epitope mapping indicates identity between the brain and placental enzymes.