A method that allows the measure of molecular weight of two well-known and closely related esterases from Drosophila mojavensis and its sibling species, D. arizonae, is here described, using native polyacrylamide gel electrophoresis at several concentrations, applying Fergunson´s principles. These enzymes, namely EST-4 and EST-5, presented molecular weight values between 81 and 91 kDa. In spite of their distinct expression pattern through the insect's life cycle, they showed properties of isoenzymes codified by distinct structural genes, supporting the hypothesis of a rather recent gene duplication event that generated both in D. mojavensis and D. arizonae, as well as in other species of repleta group. The method is simple and adequate to be applied to preliminary molecular weight determination of other enzymes without any previous purification procedure.
Esterases; Isoenzymes; molecular weight determination; Drosophila mojavensis; Drosophila arizonae; PAGE
