FIGURE 4.

Construction and optimization of the sulfation system from ATP and sulfate. (A) Schematic diagram of sulfation-modification system for CSA biosynthesis. (B) The effect of temperature on sulfation in the reaction system with 10 mM ATP, 20 mM MgSO₄, 0.5 g/L ASAK^S5, 1.0 g/L C4ST, and 2.0 g/L chondroitin for 48 h. (C) The effect of ATP concentration and MgSO₄ concentration on the sulfation in the system with ASAK^S5 (0.5 g/L), C4ST (1.0 g/L) and chondroitin (2.0 g/L) at a reaction temperature of 35°C for 48 h. ATP, adenosine 5′-triphosphate; ADP, adenosine 5′-diphosphate; PAPS, 3′-phosphoadenosine-5′-phosphosulfate; PPi, pyrophosphate; ASAK^S5, a bifunctional PAPS synthase that converts ATP to PAPS. The data are expressed as the mean ± SD from three (n = 3) biologically independent replicates. The statistical analysis was performed by two-sided t-test. *p < 0.05, **p < 0.01, ***p < 0.001; NS not significant (p ≥ 0.05).