Selective determination of the activities of neutral and acid alpha-glucosidase using discontinuous assays.
Most biological fluids contain both neutral and acid alpha-glucosidase. Optimal conditions were therefore developed for the selective determination of the activity of neutral and acid alpha-glucosidase, using 2-step, discontinuous assays. In the first step of the assay of neutral alpha-glucosidase, glucose was liberated from maltose (citrate-phosphate buffer, pH 6.8, 20 mmol/l maltose, 25 mmol/l turanose). Under these incubation conditions, turanose inhibited the residual activity of acid alpha-glucosidase almost completely without influencing the activity of neutral alpha-glucosidase. In the first step of the acid alpha-glucosidase assay, glucose was liberated from maltose (citrate-phosphate buffer, pH 3.8, 50 mmol/l maltose, 2 mol/l potassium chloride). Under these incubation conditions, potassium ions stimulate the activity of acid alpha-glucosidase and simultaneously inhibit almost completely the residual activity of neutral alpha-glucosidase. In the second step of the assay of neutral and acid alpha-glucosidase, the liberated glucose was measured by hexokinase/glucose-6-phosphate dehydrogenase. The effect of turanose and potassium ions on neutral and acid alpha-glucosidase from human urine was characterized.
D005947:Glucose / Q000032:analysis; D005959:Glucosidases / Q000032:analysis*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D007668:Kidney / Q000201:enzymology; D007700:Kinetics; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D000520:alpha-Glucosidases / Q000032:analysis*
D007202:Indicators and Reagents; D005959:Glucosidases; D000520:alpha-Glucosidases; D005947:Glucose