4.1.1.20 - 4.1.1.20 Ni-NTA column chromatography 4.1.1.20 Ni-NTA resin column chromatography 4.1.1.20 recombinant 4.1.1.20 recombinant DAPDC 4.1.1.20 recombinant enzyme from Escherichia coli strain BL21(DE3) by anion exchange and hydrophobic interaction chromatography, and gel filtration 4.1.1.20 recombinant His-tagged enzyme from Escherichia coli strain BL21(DE3) 4.1.1.20 recombinant His-tagged wild-type and mutant enzymes from Escherichia coli strain BL21(DE3) 4.1.1.20 recombinant His6-tagged enzyme from Escherichia coli strain BL21(DE3) by nickel affinity chromatography, dialysis, and gel filtration 4.1.1.20 recombinant His6-tagged wild-type and mutant enzymes from Escherichia coli strain BL21(DE3) by nickel affinity chromatography and gel filtration