title: Denatured mammalian protein mixtures exhibit unusually high solubility in nucleic acid-free pure water.
abstract: Preventing protein aggregation is a major goal of biotechnology. Since protein aggregates are mainly comprised of unfolded proteins, protecting against denaturation is likely to assist solubility in an aqueous medium. Contrary to this concept, we found denatured total cellular protein mixture from mammalian cell kept high solubility in pure water when the mixture was nucleic acids free. The lysates were prepared from total cellular protein pellet extracted by using guanidinium thiocyanate-phenol-chloroform mixture of TRIzol, denatured and reduced total protein mixtures remained soluble after extensive dialysis against pure water. The total cell protein lysates contained fully disordered proteins that readily formed large aggregates upon contact with nucleic acids or salts. These findings suggested that the highly flexible mixtures of disordered proteins, which have fully ionized side chains, are protected against aggregation. Interestingly, this unusual solubility is characteristic of protein mixtures from higher eukaryotes, whereas most prokaryotic protein mixtures were aggregated under identical conditions. This unusual solubility of unfolded protein mixtures could have implications for the study of intrinsically disordered proteins in a variety of cells.
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Junichiro
authors.initials: J
authors.lastname: Futami
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Haruna
authors.initials: H
authors.lastname: Fujiyama
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Kinoshita
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Nonomura
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Honjo
authors.affiliation: Department of Biotechnology, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Tada
authors.affiliation: Department of Immunotherapeutics, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Matsushita
authors.affiliation: Department of Protein Structure, Function and Design, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Abe
authors.affiliation: Department of Immunotherapeutics, The University of Tokyo Hospital, Tokyo, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Kakimi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002725:Chloroform; D004926:Escherichia coli; D006146:Guanidines; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D009696:Nucleic Acids / Q000032:analysis; D010636:Phenols; D010957:Plasmids / Q000235:genetics; D011489:Protein Denaturation; D011506:Proteins / Q000737:chemistry*; D012995:Solubility; D013861:Thiocyanates; D014162:Transfection; D014867:Water / Q000737:chemistry*; D015003:Yeasts
chemical_list: D006146:Guanidines; D009696:Nucleic Acids; D010636:Phenols; D011506:Proteins; D013861:Thiocyanates; D014867:Water; C054436:guanidine thiocyanate; D002725:Chloroform