Glycan trimming is necessary for rhGAA activation. Michaelis–Menten kinetics of various rhGAA forms using 4MU-α-Glc or glycogen as substrates. Reactions were carried out for 60 min at 37 °C. Data points were fitted to the Michaelis–Menten equation using Prism (GraphPad), and error bars represent the mean ± SD. One-way ANOVA with Fisher’s LSD post hoc test was also performed using Prism (GraphPad). A p-value of <0.005 is denoted by two asterisks (∗∗). A, Michaelis–Menten kinetics of rhGAA forms using varying amounts of the small fluorogenic substrate 4MU-α-Glc. B, Vmax for rhGAA forms in 4MU-α-Glc hydrolysis. C, Km values for rhGAA form sin 4MU-α-Glc hydrolysis. D, Michaelis–Menten kinetics of rhGAA forms using varying amounts of bovine liver glycogen. E, Vmax for rhGAA forms in glycogen hydrolysis. F, Km values for rhGAA forms in glycogen hydrolysis. GAA, acid alpha-glucosidase; rhGAA, recombinant human GAA.