Nonserine esterases from rat liver cytosol.

An effort to identify the major general esterases of rat liver cytosol that are insensitive to the serine esterase inhibitor paraoxon (diethyl 4-nitrophenyl phosphate) has led to the isolation of a dozen enzymes. Four of these are electrophoretically homogeneous. Although purified on the basis of their hydrolytic activity toward 4-nitrophenyl acetate, each of the enzymes has a very broad and overlapping substrate specificity for aromatic esters. Thiol esters serve as substrates but, within the limits of the methods used, amides are not hydrolyzed.