4.1.2.52 by anion exchange, hydrophobic interaction, and gel filtration chormatography 722258 4.1.2.52 metal affinity and size exclusion chromatography, Superdex 200 column used 722955 4.1.2.52 wild type protein and R70A mutant protein purified to homogeneity using anion exchange, hydrophobic interaction, and gel filtration chormatography 721601