Fig. 4. Kinetics of sulfonadyn-33 with respect to GTP. Double-reciprocal plots of various sulfonadyn-33 concentrations at varying substrate (GTP at 80–160 μM, S) and reaction velocity (V). The concentrations were 3 (▼) 5 (◆), 6 (■), and 7 (●) μM sulfonadyn-33. Error bars are the mean ± SEM of three independent experiments each conducted in triplicate. Kinetic constants for GTP were K_m 20.8 ± 3.8 μM and V_max 590 ± 67 nmol mg⁻¹ min⁻¹.