1.2.1.39 - 390292, 390300 1.2.1.39 by gel filtration, 15.9fold with a 0.21% yield 690567 1.2.1.39 native enzyme 126fold by cross-flow filtration, ultracentrifugation, and anion exchange chromatography, recombinant Strep-tagged enzyme 137fold from Escherichia coli strain DHalpha by affinity chromatography on a Strep-Tactin column 742786 1.2.1.39 Ni-affinity column chromatography 762624 1.2.1.39 recombinant N-terminally His-tagged enzyme, NPADH, from Escherichia coli strain BL21(DE3) by nickel affinity chromatography and ultrafiltration to over 90% purity 741787