Placental Choline Acetyltransferase Purification and Properties

Abstract

Several attempts have been made in the past to purify cholineacetyltransferase (CAT) (EC. 2.3.1.6). Someauthors (4,6,9,10) have obtained a purified enzyme with a very high specific activity. However, their preparations showed several bands in SDS Polyacrylamide gel electrophoresis (PAGE), and they concluded that they were heterogeneous. In addition, it was observed (6,9) that the enzyme was not highly antigenic even though their immunserum, while not monospecific, was able to inhibit up to 98% of the enzyme activity. In contrast, other authors (1,12) have obtained an enzyme with a very low specific activity compared to the previous group and have concluded that their preparations were pure even though several bands were observed on SDS PAGE (1). They found CAT to be highly antigenic and claimed that their antisera were monospecific. However, only 50% of the enzyme activity was inactivated by the antisera. Some discrepancies wre also observed regarding the physicochemical properties of CAT (for review, see Ref. 7).