Expression of Recombinant Human α-Glucosidase in HEK293 Cells

In mammals, intestinal α-glucosidase exists as a maltase-glucoamylase complex (MGAM) and a sucrase-isomaltase complex (SI). In this study, we transiently expressed human MGAM and SI in human embryonic kidney 293 (HEK293) cells. At pH 6.0 and 37 °C, the MGAM-expressing HEK293 cells extract (MGE) exhibited maltase, glucoamylase, and isomaltase activities but not sucrase activity, whereas the SI-expressing HEK293 cells extract (SIE) exhibited sucrase, isomaltase, and maltase activities but not glucoamylase activity. The apparent K_m value of the MGE for maltose hydrolysis was 14-26% of that of the SIE for maltose, sucrose, and isomaltose hydrolysis. The respective apparent V_max values of the MGE and SIE for sucrose and isomaltose hydrolysis were 0% and 6% and 10% and 42% of those for maltose hydrolysis. These results indicated that the maltase activities of MGAM and SI were higher than those of sucrase and isomaltase.