Purification using adsorption membrane butyrylcholinesterase

Method for preparing a composition enriched butyrylcholinesterase from a biological source having butyrylcholinesterase, the method comprising the steps of: applying biological source having a butyrylcholinesterase anion exchange material attached to a membrane; washing the material; and butyrylcholinesterase eluting the anion exchange material, wherein the content of butyrylcholinesterase is enriched after the anion exchange at least 10 times the total protein in the composition as measured by total protein butyrylcholinesterase activity.