Active site kinetics of horse serum cholinesterase.
Horse serum Cholinesterase hydrolyzes choline and p-nitrophenol esters at different rates. Deacylation and acylation seem to be the rate-limiting step for charged and uncharged substrates respectively. Activation energy is similar for the acetic, propionic, and butyric esters of thiocholine, but it is higher for p-nitrophenylpropionate. Inhibition by the tetramethyl-ammonium ion is competitive. Tetraethyl-, tetrapropyl-, and tetrabutyl-ammonium ions are mixed-type inhibitors. The pH studies demonstrated the existence of a residue, pK = 6.33, involved in catalysis.
D000818:Animals; D001665:Binding Sites; D002151:Calorimetry; D002802:Cholinesterases / Q000097:blood*; D006736:Horses; D007700:Kinetics; D008433:Mathematics
D002802:Cholinesterases