MOLECULAR FORMS OF CHOLINESTERASES 3. STRUCTURE AND ACTION MECHANISM OF ESTERATIC ACTIVE CENTER 4. GENETIC VARIANTS OF BChE 5. FUNCTIONS OF BChE

Butyrylcholinesterase is involved three different enzymatic activities in its structure like its sister enzyme, acetylcholinesterase: esterase, aryl acylamidase and peptidase (or protease). Whereas the clear role of acetylcholinesterase in cholinergic neurotransmission is well defined, the real physiological function of butyrylcholinesterase is still unknown. Both enzymes have similar molecular forms with different tissue distribution. Esteratic activity of butyrylcholinesterase becomes more important in scavenging of organophosphate and carbamate inhibitors before they reach to acetylcholinesterase; in regulating cholinergic transmission in the absence of acetylcholinesterase and in inactivation of some drugs such as cocaine aspirin, amitriptyline or in activation of others such as bambuterol, heroin. It is suggested that aryl acylamidase activity plays a role in crosstalking between seratonergic and cholinergic neurotransmission systems. In addition, peptidase activity of butyrylcholinesterase has a function in the development and progression of Alzheimer disease due to cause the production of β-amyloid protein and to help its diffusion to β-amyloid plaques.