EC Number   |
|---|
    6.3.1.21 | Ni-NTA column chromatography, HQ20 column chromatography and Superdex S200 gel filtration |
| 6.3.1.21 | recombinant enzyme from Escherichia coli strain BL21(DE3) by streptomycin sulfate precipitation, anion exchange chromatography, ultrafiltration, dialysis, and gel filtration, followed by dialysis and ultrafiltration |
| 6.3.1.21 | recombinant enzyme from Escherichia coli strain TX635 by streptomycin sulfate precipitation, dialysis, anion exchange chromatography, and ultrafiltration, followed by another different step of anion exchange chromatography, dialysis, and ultrafiltration |
| 6.3.1.21 | recombinant wild-type and mutant enzymes from TX680 auxotrophic cells by gel filtration, anion exchange chromatography, and dialysis, to over 90% purity |
