Over 20 monosaccharides, disaccharides and sugar derivatives were tested as the reversible inhibitors of yeast alpha-glucosidase. The variation of second-order rate constants (kcat/Km) for the alpha-glucosidase-catalyzed hydrolysis of alpha-PNP-Glc shows a bell-shaped dependence on pH with pK 1 = 5.6 and pK2 = 6.8. No kinetic solvent isotope effect was observed when the reaction was carried out in D2O instead of H2O. The study of glycon hydroxyl groups interaction with alpha-glucosidase shows no obvious correlation in the binding of the monosaccharides with anomeric configuration. The major binding determinant of the substrate is proved to be the aglycon unit. pH-inhibition study indicates that there are two classes of monosaccharide inhibitors, which have different binding dependence on the ionizing group around the enzymatic binding sites. Multiple inhibition studies suggest that there are at least three binding sites on the enzyme Different methods were used to extract the bioactive ingredients from plant hyssop and the inhibition activity of these extracts to yeast alpha- and almond beta-glucosidase was studied. One partly purified sample has demonstrated to be a pretty potent inhibitor of alpha-glucosidase and it possibly could act as a lead compound for further therapy potential study
