2.7.1.173 native enzyme partially by ammonium sulfate fractionation 718225 2.7.1.173 recombinant His-tagged NRK1 from Escherichia coli strain BL21(DE3) by nickel affinity chromatography and gel filtration 682879 2.7.1.173 recombinant Nrk1 and Nrk2 from Escherichia coli by metal chelate affinity chromatography 718250 2.7.1.173 recombinant Nrk2 from Escherichia coli by metal chelate affinity chromatography 718250