Isolation and characterization of a butyrylesterase from human erythrocytes.
Human erythrocytes contain a butyrylesterase which, judging from the ease with which it can be solubilized, is present in the cytoplasm of these cells. This enzyme has been isolated and a number of its properties characterized. The purified enzyme hydrolyzed butyryl esters with both a lower Km and higher V than is seen with esters containing longer or shorter acyl groups. It has a molecular weight of 320 000 and an isoelectric point of 4.1. This low isoelectric point is apparently a result of the relatively high content of glutamic and aspartic acids. The stability of the isolated butyrylesterase has been examined under a number of different conditions. The enzyme is inhibited by low concentrations of Hg2+, Cd2+, Zn2+ and the organophosphorus compound Mipafox, but is insensitive to eserine. The properties of this butyrylesterase, including its ability to hydrolyze thiocholine esters at a relatively rapid rate (albeit with a high Km), are a mixture of those expected for an arylesterase and a cholinesterase.
D000596:Amino Acids / Q000032:analysis; D002087:Butyrates; D002265:Carboxylic Ester Hydrolases / Q000097:blood / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D004912:Erythrocytes / Q000201:enzymology*; D006801:Humans; D007526:Isoelectric Point; D007700:Kinetics; D008970:Molecular Weight; D013379:Substrate Specificity
D000596:Amino Acids; D002087:Butyrates; D002265:Carboxylic Ester Hydrolases; C021487:butyrylesterase