Solubilization of 20S acetylcholinesterase from chick retina

A 20S form of acetylcholinesterase has been solubilized from young chick retinas by means of a buffered salt-detergent solution containing EDTA. The release of this fast-sedimenting form of the enzyme is selectively blocked by the presence of even small amounts of Ca⁺⁺ in the homogenization medium. The collagen-tailed nature of this molecular species of acetylcholinesterase has been ascertained by collagenase digestion. This finding suggests that the avian central nervous system contains asymmetric, collagen-tailed quaternary structural forms of acetylcholinesterase as is the case in skeletal muscle and cholinergic ganglia.