title: Characterization and polyelectrolyte precipitation of beta-galactosidase containing genetic fusions of charged polypeptides.
abstract: Genetically engineered versions of beta-galactosidase were constructed through the addition of charged polypeptide fusion tails for the purpose of enhancing polyelectrolyte precipitation. Negatively charged aspartic acid tails and positively charged poly(arginine) tails were added to beta-galactosidase from Escherichia coli. These fusion proteins were all shown to possess specific activity equal to that of the native enzyme. Gel permeation and ion-exchange chromatography provided evidence concerning the integrity of the tails as well as their altered charge characteristics. All enzymes containing charged tails displayed enhanced polyelectrolyte precipitation over the native enzyme. An optimal number of charged residues, beyond which no further enhancement of precipitation was observed, was found to be approximately 10 residues for each type of tail. No interference from nucleic acids was observed in the precipitation of positively tailed beta-galactosidase.
authors.affiliation: Department of Chemical Engineering, Iowa State University, Ames 50011.
authors.forename: M Q
authors.initials: MQ
authors.lastname: Niederauer
authors.forename: I
authors.initials: I
authors.lastname: Suominen
authors.forename: M A
authors.initials: MA
authors.lastname: Rougvie
authors.forename: C F
authors.initials: CF
authors.lastname: Ford
authors.forename: C E
authors.initials: CE
authors.lastname: Glatz
mesh_terms: D000180:Acrylic Resins; D000595:Amino Acid Sequence; D000838:Anions; D001483:Base Sequence; D002412:Cations; D011232:Chemical Precipitation; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000201:enzymology; D008969:Molecular Sequence Data; D011094:Polyethyleneimine; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000302:isolation & purification*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000235:genetics* / Q000302:isolation & purification
chemical_list: D000180:Acrylic Resins; D000838:Anions; D002412:Cations; D011993:Recombinant Fusion Proteins; C006903:carbopol 940; D011094:Polyethyleneimine; D001616:beta-Galactosidase