Soluble form of acetylcholinesterase from rabbit enterocytes: comparison of its molecular properties with those of the plasma membrane species.

A soluble form of acetylcholinesterase was shown to be present in rabbit enterocytes. The enzyme was obtained from a high-speed supernatant (105,000 X g centrifugation) after homogenization of intestinal mucosa without detergent. It was shown to possess no obvious hydrophobic character and could be classified as a low-salt-soluble (LSS) acetylcholinesterase. Sucrose gradient centrifugation revealed a single enzyme species with a sedimentation coefficient of 3.9 +/- 0.2S. By gel filtration performed in HPLC the enzyme was eluted as a protein corresponding to an Mr of 72,000 +/- 3,000. It could be precipitated with concanavalin A by affinoelectrophoresis, but the catalytic activity was not affected by the lectin. Our results are consistent with a G1 globular form for this soluble acetylcholinesterase which differs very clearly from detergent-soluble forms also found recently in the plasma membranes of rabbit enterocytes.