Characterization of alpha-glucosidase at the tips of the chemosensory setae of the fly, Phormia regina

The properties of α-glucosidase activity located at the tip of the labellar chemosensory seta of the blowfly were examined using the ultramicro method for determination of hexose. The enzyme activity was independent over a wide range of pH (3·0–8·0) and inhibited by Tris in a competitive manner and by Ca²⁺ ion in low concentration. By comparison of the present results with those for the α-glucosidase isozymes in the extract from the proboscis, it became clear that the enzyme in the intact state had properties to distinguish it from the enzyme in the soluble form. Furthermore, apparent similarities were observed between the properties of the enzyme in the intact state and those of the labellar sugar receptor examined electrophysiologically.