1-Alkyl-2-acetylglycerophosphocholine Esterase: A lipoprotein-associated PHOSPHOLIPASE A2 which modulates the action of PLATELET ACTIVATING FACTOR by hydrolyzing the SN-2 ester bond to yield the biologically inactive lyso-platelet-activating factor. It has specificity for phospholipid substrates with short-chain residues at the SN-2 position, but inactive against long-chain phospholipids. Deficiency in this enzyme is associated with many diseases including ASTHMA, and HYPERCHOLESTEROLEMIA.EsterasesCarboxylic Ester Hydrolases: Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.Naphthol AS D Esterase: Hydrolytic enzyme activity used as a histocytochemical test for the presence of esterases in tissue. Substrate used is 3-hydroxy-4'-nitro-2-naphthanilide chloroacetate (naphthol AS-D).Sterol Esterase: An enzyme that catalyzes the hydrolysis of CHOLESTEROL ESTERS and some other sterol esters, to liberate cholesterol plus a fatty acid anion.Acetylesterase: An enzyme that catalyzes the conversion of acetate esters and water to alcohols and acetate. EC 188.8.131.52.Carboxylesterase: Carboxylesterase is a serine-dependent esterase with wide substrate specificity. The enzyme is involved in the detoxification of XENOBIOTICS and the activation of ester and of amide PRODRUGS.EstersIsoflurophate: A di-isopropyl-fluorophosphate which is an irreversible cholinesterase inhibitor used to investigate the NERVOUS SYSTEM.Alkylation: The covalent bonding of an alkyl group to an organic compound. It can occur by a simple addition reaction or by substitution of another functional group.