Quantitation of Alpha-Glucosidase Activity Using Fluorinated Carbohydrate Array and MALDI-TOF-MS

Quantitation of alpha-glucosidase (α-GD) activity is of significance to diagnosis of many diseases including Pompe disease and type II diabetes. We report here a new method to determine α-GD activity using matrix-assisted laser desorption/ionization (MALDI)-time-of-flight (TOF) mass spectrometry (MS) in combination with carbohydrate microarray and affinity surface chemistry. Carbohydrate probes are synthesized for capture of the enzymatic reaction products and the adducts are loaded onto a fluorinated gold surface to generate an array, which is followed by characterization by MALDI-TOF-MS. The ratio of intensities is used to determine the level of activity of several enzymes. In addition, half maximal inhibitory concentration (IC50) of acarbose and epigallocatechin gallate are also determined using this approach, and the results agree well with the reported values. This method is advantageous as compared to conventional colorimetric techniques that typically suffer matrix interference problems from samples. The use of the polyfluorinated surface has effectively suppressed the interference.