The developmental multiplicity and isoenzyme status of rat esterases

Abstract

1. 1.|With the aim of clarifying the isoenzyme status of esterases, the developmental and physicochemical properties of these enzymes have been studied in an extensive range of rat tissues. 2. 2.|A total of 33 multiple forms of soluble esterase activity have been resolved, and the occurrence of these individual forms in the different tissues interrelated. 3. 3.|By means of substrate and inhibitor studies, these heteromorphs have been characterized into 4 main classes: carboxylesterases, arylesterases, acetylesterases and cholinesterases. 4. 4.|All of these classes are heterogenous—the soluble carboxylesterases existing as 15 separate forms, arylesterases 5, cholinesterases 10, and acetylesterases 3. 5. 5.|Further differentiation of the multiple forms in these classes has been achieved on the basis of the physicochemical and developmental parameters utilized. This treatment would appear to implicate at least 13 structural genes in the biosynthesis of soluble rat esterases.