Fig. 5

Effect of NAD⁺ regeneration system on UDP-GlcA formation. a BL21-PiUDH, BL21-TkNOX and plasmid-free E. coli BL21 (DE3) cells were fermented and used as catalysts. Initially, BL21-PiUDH cells were incubated in a mixture containing 2.3 mM UDP-Glc, 0 mM NAD⁺ and 200 mM sodium phosphate (pH10). Then, groups containing the same components, and an additional BL21-TkNOX or BL21 cells respectively, were introduced into the reactions. These mixtures were incubated for 0.5 h and supernatants were detected by HPLC. b BL21-PiUDH and BL21-PiUDH-TkNOX cells were fermented and used as catalysts. BL21-PiUDH or BL21-PiUDH-TkNOX cells were incubated with 2.3 mM UDP-Glc, without extra supplementation, at 65 °C for 0.5 h. These mixtures were incubated for 0.5 h and supernatants were detected by HPLC. And bars indicate the range of assay results from three different batches