Subunits of Choline Acetyltransferase (Ec 2.3.1.6)

The molecular weight of choline acetyltransferase is determined to be approx 87,000‐89,000 daltons. There are 808 amino acid residues per molecule of the enzyme with a calculated mol. wt of 89,300. Peptides of ChAc were studied after tryptic digestion, cyanogen bromide and BNPS‐skatole cleavages. The results of these studies suggest that the enzyme contains 6 identical subunits with 133 amino acid residues each and with a calculated molecular weight of 14,700 daltons for the monomer. This conclusion is supported by the fact that serine is the only amino terminal residue and alanine is the only carboxyl‐terminal group.