title: Negatively charged purification tags for selective anion-exchange recovery.
abstract: A novel strategy for the highly selective purification of recombinant fusion proteins using negatively charged protein domains, which were constructed by protein design, is described. A triple alpha-helical domain of 58 amino acids was used as scaffold. Far-ultraviolet circular dichroism measurements showed that the designed domains had very low alpha-helicity in a low-conductivity environment in contrast to the scaffold. The secondary structure could be induced by adding salt, giving a structure comparable to the parental molecule. Further studies showed that the new domains were able to bind to an anion exchanger even at pH values down to 5 and 6. Gene fusions between one of the designed domains and different target proteins, such as green fluorescent protein (GFP), maltose binding protein (MBP) and firefly luciferase, were also constructed. These gene products could be efficiently purified from whole cell lysates at pH 6 using anion-exchange chromatography.
authors.affiliation: Department of Biotechnology, Royal Institute of Technology (KTH), AlbaNova University Center, Roslagstullsbacken 21, SE-106 91 Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Hedhammar
authors.forename: T
authors.initials: T
authors.lastname: Gräslund
authors.forename: M
authors.initials: M
authors.lastname: Uhlén
authors.forename: S
authors.initials: S
authors.lastname: Hober
mesh_terms: D000595:Amino Acid Sequence; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D002852:Chromatography, Ion Exchange / Q000379:methods; D002942:Circular Dichroism; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D011993:Recombinant Fusion Proteins