4.2.1.115 | recombinant GST-tagged enzyme from Escherichia coli strain BL-21 GOLD by glutathione affinity chromatography, proteolytic removal of the GST-tag, and ultrafiltration, recombinant His6-tagged enzyme from Escherichia coli strain Rosetta(DE3) by nickel affinity chromatography, proteolytic removal of the His-tag, another step of nickel affinity chromatography, and desalting gel filtration, thereby the recombinant protein corresponds to the native enzyme in which the initial methionine is replaced by GPGS sequence resulting from the cleavage site |