Abstract:
The Dionex CaboPac
TM PA10 BioLC
TM Analyical 2 mm × 250 mm column was used with a protective column (Dionex CaboPac
TM PA10 BioLC
TM Guard 2 mm × 50 mm). 100 mmol·L
-1 sodium hydroxide solution was used as eluent; the flow rate was 0.25 mL·min
-1. Sample tray temperature: 35 ℃. The pulse amperometric detector was adopted, and the waveform was Gold CWE, Ag-AgCl RE, Carbo, Quad. The samples were cultured with 8 concentrations of glycogen substrates (0.31, 1.25, 2.5, 5, 10, 20, 30, and 40 mg·mL
-1).
D-Glucose concentrations were measured at 5 different time points (T0, T1, T2, T3 and T4). The glucose concentration from T1 to T4 minus the glucose concentration at T0. The reaction rate was calculated at different glycogen substrate concentrations. These reaction rates are plotted against substrate concentrations using Michaelis-Menten equation. The kinetic parameters were expressed as
Vmax (nmol·mg
-1·min
-1) and
Km (mg·mL
-1). The RSD of glucose standard curve
R2 (
n = 6, linear range: 1.25-500 μmol·L
-1) was 0.1% and the RSD (
n = 6) of the slope of the standard curve was 2.2%. The mean limit of quantitation was 0.14 μmol·L
-1, and the mean limit of detection was 0.05 μmol·L
-1. The RSD of
Km and
Vmax were 4.4% and 4.6% respectively in three separate experiments. The durability of the method was good. The method was developed for the on-line automatic determination of the hydrolysis kinetics of acid
α-glucosidase (GAA) for injection by ion chromatography. The method has good precision, repeatability and durability, and can be used for the determination of glycogen hydrolysis kinetics of GAA for injection, and could reference value for the enzyme kinetics evaluation of recombinant enzyme replacement therapy.