Kinetic studies on the active site of pig serum .ALPHA.-glucosidase and buckwheat .ALPHA.-glucosidase

Kinetic studies on the active site of pig serum α-glucosidase and buckwheat α-glucosidase catalyzing the hydrolyses of maltose and soluble starch were made. The kinetic features obtained by the experiments with the mixed substrates, the linearity of Lineweaver-Burk plots, and the dependence of the apparent Michaelis constants and the apparent maximal velocities on the fraction ƒ of maltose in the mixed substrate solutions, that is, ƒ=maltose/(maltose+soluble starch), were in good agreement with those expected for the single active site catalyzing the hydrolyses of both substrates. From the results it was concluded that these enzymes attacked maltose and soluble starch by the single active site mechanism.