A COMPARATIVE-STUDY OF THE ENZYMOLOGICAL FEATURES OF ALPHA-AMYLASE IN THE DROSOPHILA-MELANOGASTER SPECIES SUBGROUP

A comparative study was done on the enzymological features of a-amylase among six sibling species belonging to the Drosophila melanogaster species subgroup. The pH optima were 7.6 for D. melanogaster, D. mauritiana and D. simulans and 7.4 for D. erecta, D. teissieri and D. yakuba. The temperature optima were commonly 37 C in all species studied. However, there are two types of temperature dependence; a strict one as observed in D. melanogaster, D. mauritiana and D. simulans, and a flat one as observed in D. erecta, D. teissieri and D. yakuba. These separations are consistent with the general phylogeny within this species subgroup. The substrate dependence was almost the same in all the species studied. The V-max and K-m were also estimated for each species. We found clear differences in the enzymological features between the species. Thus these differences might reflect an adaptation of the amylase enzyme system to speciation in this species subgroup.