5.1.1.4 - 2121, 2122, 2125, 730678 5.1.1.4 2 forms of enzyme: one binds L-Pro and the other D-Pro 2124 5.1.1.4 by affinity chromatography using nickel-nitrilotriacetic acid-agarose columns 705596 5.1.1.4 cobalt metal-affinity resin column chromatography 715163 5.1.1.4 recombinant His-tagged enzyme from Escherichia coli strain BL21(DE3) by nickel affinity chromatography 728600 5.1.1.4 recombinant His6-tagged enzyme from Escherichia coli strain BL21(DE3) by nickel affinity chromatography 727156 5.1.1.4 TcPRACA protein is purified with immobilized metal affinity chromatography on nickel columns. The active peak is further submitted to gel filtration chromatography at 2.5 ml/min in a Superdex200 26/60 column 676832