A new monomeric α-amylase inhibitor from the tetraploid emmer wheat is mostly active against stored product pests

Abstract: The tetraploid domesticated emmer wheat, Triticum turgidum L. subsp. dicoccon, expresses α-amylase protein inhibitors of varying sizes and assemblies, i.e. dimers and heterotetramers of polypeptide chains of about 12–15 kDa. Although genetic studies have shown the presence of coding sequences for monomeric inhibitors in tetraploid wheat and whole-seeds proteomic studies have indicated their expression, until now there has been no isolation nor characterization of such proteins. In this study, for the first time, an inhibitory protein of human salivary and Tenebrio molitor, Tribolium castaneum, Sitophilus oryzae, and Ephestia kuehniella α-amylase (EC 3.2.1.1), was isolated from whole flour extracts of a tetraploid wheat and its sequence was determined by MS analyses. The inhibitor acts more strongly against coleopteran α-amylases than against those from E. kuheniella and human saliva. The inhibitory characteristics along with the putative sequence determination reported in the present study, allows for further evaluation towards its utilization as a post-harvest protection strategy against insect infestations.