Kinetic Studies on Allosteric Properties of Honeybee alpha-Glucosidase

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(1)Three kinds of alpha-glucosidases(HbG-I, HbG-II and HbG-III)were purified from honeybee. In addition, an alpha-glucosidase was also purified from honey.(2)HbG-I, II and III were immunologically confirmed to be distributed in ventriculus, hemolymph(and also ventriculus)and hypopharyngeal gland, respectively. The alpha-glucosidase from honey was identified to be the same enzyme as HbG-III.(3)HbG-I and II showed allosteric behaviors. These two enzymes were regarded as so-called hysteretic enzyme which showed a relatively slow conformational change in second or minute order.(4)The subsites affinities in active site of HbG-I, II and III were evaluated. Subsite 1, 2 and 3 having positive values in three enzymes were considered to be effective for binding of substrate to active site.(5)Honeybee alpha-glucosidase, which is the same enzyme as HbG-III, was considered to be secreted into honeydew from hypopharyngeal gland.