Choline Acetyltransferase: a Review With Special Reference to its Cellular and Subcellular Localization

The chapter discusses only the recent developments of analogs of CoA as ChAc inhibitors and the physiological importance of the possible regulation of ChAc by Cl - is presented.

Abstract

This chapter focuses on the purification and localization of choline acetyltransferase (ChAc). There is a discussion of the two most often used assays, which are, the Fonnum assay and the Schrier and Shuster assay. ChAc is well known to be a specific protein of the nervous system. This assumption is not far from reality, but ChAc also exists in nonnervous tissue, and paradoxically, it appears that nonnervous tissue has been the best source of starting material for ChAc purification. ChAc with a specific activity around 1 pmole/minute per mg is obtained starting from the bacteria Lactobacillirs plantarum. ChAc is present in brain tissue, but there its distribution is heterogeneous. The chapter reviews the mechanism of action of ChAc and presents some findings related to the effect of Cl- on the enzyme. The chapter discusses only the recent developments of analogs of CoA as ChAc inhibitors. The physiological importance of the possible regulation of ChAc by Cl- is presented. In the multi-enzymatic complex involved in Ach synthesis local concentration of Cl- may rapidly increase in response to presynaptic depolarization.