3.5.1.25 - 3.5.1.25 anion exchange column 3.5.1.25 recombinant enzyme NagA from Escherichia coli strain BL21(DE3) by anion exchange and hydrophobic interaction chromatography, followed by gel filtration 3.5.1.25 recombinant His-tagged enzyme from Escherichia coli strain C43(DE3) by nickel affinity chromatography and dialysis 3.5.1.25 recombinant His6-tagged wild-type and mutant enzymes from Escherichia coli by cobalt affinity and anion exchange chromatography, followed by gel filtration 3.5.1.25 size exclusion column and anion exchange column