Assessing of a-Amylase Activity of Midgut in Wheat Bug Eurygaster maura

To determine of a-amylase activity in the midgut of Eurygaster maura, some of adult insect was collected and their gut isolated and characterized. Enzyme samples from midguts of adults were prepared by the method of Cohen with slight modifications. a-Amylase activity was assayed based on Bernfeld method by the dinitrosalicylic acid (DNS) procedure. The activity of a-amylase in midgut was 0.083 U/insect. The optimum pH and temperature for the enzyme activity was determined to be 66.5 and 30-35°C, respectively. The enzyme activity was inhibited by addition of EDTA (Ethylenediamine tetraacetic acid) urea, CaCl2, MgCl2 and SDS but Mg2+, NaCl and KCl enhanced enzyme activity.