Butyrylcholinesterase (BChE) is a serine hydrolase that is structurally similar to acetylcholinesterase (AChE), but differs in substRate specificities and inhibitor sensitivities. BChE can, unlike AChE, efficiently hydrolyze larger esters of choline such as butyrylcholine and benzoylcholine. The enzyme is a tetrameric glycoprotein with four equal subunits (110 kDa each). The enzyme is activated by Ca2+ and Mg2+ and the activity is constant over the pH range 6.0-8.0. It is inhibited by Betaine, nicotine, organophosphates, carbamates.