Fig. 3. Steady-state GDH activity assay. (a) The absorbance of NADH at 340 nm generated in aCSF containing 0.1 mg mL⁻¹ (ca. 300 nM) GDH, 250 μM NAD⁺ and 5 mM glutamate in the absence and presence of 16 μM Yb³⁺. Linear fitting of the steady-state profile during 10–30 s yields the corresponding slope for reaction rate calculation. (b) The calculated overall reaction rate of NADH production in the absence and presence of 16 μM Yb³⁺. Error bars represent standard error of the mean (n = 3, t-test, ***P < 0.001).