Butyrylcholinesterase

Butyrylcholinesterase (BChE), also known as pseudocholinesterase or plasma cholinesterase, is a serine hydrolase enzyme in the cholinesterase family. It is primarily located in blood plasma and is synthesized by the liver. The enzyme is encoded by the BCHE gene.

BChE hydrolyzes choline-based esters, with butyrylcholine as its preferred substrate, and it hydrolyzes acetylcholine more slowly than acetylcholinesterase. It has broad substrate specificity, including certain ester drugs such as the muscle relaxant succinylcholine and several local anesthetic esters. In the bloodstream, BChE circulates as different glycoforms and tetrameric assemblies.

Clinical significance: Variation in BChE activity can affect responses to ester-containing anesthetics. Individuals with reduced or absent BChE activity may experience prolonged neuromuscular blockade after succinylcholine administration. Genetic variants of BCHE or acquired factors can reduce activity. BChE activity is measured in clinical laboratories, often reported as a dibucaine or pseudocholinesterase activity; the dibucaine number helps predict susceptibility to prolonged effects.

Organophosphate inhibition: BChE is inhibited by organophosphate nerve agents and pesticides, and it is studied as a bioscavenger to protect against organophosphate poisoning. It is also used in research and forensic contexts as a marker of cholinesterase status; levels can be affected by liver disease, pregnancy, and certain medications.