What does esterase mean?
An esterase is any enzyme belonging to the hydrolase class that breaks an ester into its two constituent parts: an alcohol and an acid. The reaction it catalyses — hydrolysis — involves water splitting the chemical bond holding the ester together. Esterases are widespread in nature and essential to living systems: in the human body they digest dietary fats, deactivate many drugs, and destroy neurotransmitters such as acetylcholine once they have relayed their signal at a nerve synapse. Familiar members include lipase, which breaks down fats in digestion, and acetylcholinesterase, which terminates nerve impulses. Because some pesticides and nerve agents work by inhibiting acetylcholinesterase, measuring esterase activity is clinically important in diagnosing toxic exposures. The word derives from 'ester' plus '-ase', the standard suffix for enzymes, and is used almost entirely in scientific contexts rather than everyday speech.
nounAn enzyme that catalyses the hydrolysis of an ester into its component alcohol and acid.
- (biochemistry) Any enzyme that catalyses the hydrolysis of an ester bond, yielding an alcohol and a carboxylic acid.
"The blood test measured cholinesterase activity to check for exposure to certain pesticides."
"Carboxylesterases in the liver play a key role in metabolising many common medications."
"Organophosphate poisoning is diagnosed partly by measuring depressed acetylcholinesterase activity in red blood cells."
Regular plural; used when discussing multiple types or instances of the enzyme.
"Several different esterases are involved in breaking down the drug in the bloodstream."
Without esterases in your liver and blood, many drugs and pesticides would linger in your body far longer than they should — these enzymes are your built-in chemical cleanup crew.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of esterase
The word 'esterase' combines 'ester' — coined in the 19th century from German 'Essigäther' ('vinegar ether'), itself ultimately linked to Latin 'acetum' meaning vinegar — with '-ase', the suffix introduced by French chemist Émile Duclaux around 1896 to denote enzymes generally. The term arose as biochemists classified enzymes by the type of bond they cleaved, placing ester-hydrolysing enzymes together under one name. It shares its 'ester' root with related biochemical terms such as 'polyester' and 'esterification'.
How esterase is actually used
A technical term used almost exclusively in biochemistry, pharmacology, toxicology, and clinical medicine. It is rarely encountered outside scientific writing. Often appears with a specific prefix naming the substrate, e.g. cholinesterase, lipase (a triacylglycerol esterase), phosphoesterase.
Easily confused with esterase
Ester is the chemical compound itself, while esterase is the enzyme that breaks it down.