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

A comparative study was done on the enzymological features of a-amylas e among six sibling species belonging to the Drosophila melanogaster s pecies subgroup. The pH optima were 7.6 for D. melanogaster, D. maurit iana 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. Ho wever, 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 separ ations are consistent with the general phylogeny within this species s ubgroup. The substrate dependence was almost the same in all the speci es studied. The V-max and K-m were also estimated for each species. We found clear differences in the enzymological features between the spe cies. Thus these differences might reflect an adaptation of the amylas e enzyme system to speciation in this species subgroup.