title: Universality of protein reentrant condensation in solution induced by multivalent metal ions.
abstract: The effective interactions and phase behavior of protein solutions under strong electrostatic coupling conditions are difficult to understand due to the complex charge pattern and irregular geometry of protein surfaces. This distinguishes them from related systems such as DNA or conventional colloids. In this work, we discuss the question of universality of the reentrant condensation (RC) of proteins in solution induced by multivalent counterions, i.e., redissolution on adding further salts after phase separation, as recently discovered (Zhang et al., Phys Rev Lett 2008; 101:148101). The discussion is based on a systematic investigation of five different proteins with different charge patterns and five different multivalent counterions. Zeta potential measurements confirm the effective charge inversion of proteins in the reentrant regime via binding of multivalent counterions, which is supported by Monte Carlo simulations. Charge inversion by trivalent cations requires an overall negative net charge of the protein. Statistical analysis of a representative set of protein sequences reveals that, in theory, this effect could be possible for about half of all proteins. Our results can be exploited for the control of the phase behavior of proteins, in particular facilitating protein crystallization.
authors.affiliation: Institut für Angewandte Physik, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, Tübingen 72076, Germany. Fajun.zhang@uni-tuebingen.de
authors.forename: Fajun
authors.initials: F
authors.lastname: Zhang
authors.forename: Sophie
authors.initials: S
authors.lastname: Weggler
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Ziller
authors.forename: Luca
authors.initials: L
authors.lastname: Ianeselli
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Heck
authors.forename: Andreas
authors.initials: A
authors.lastname: Hildebrandt
authors.forename: Oliver
authors.initials: O
authors.lastname: Kohlbacher
authors.forename: Maximilian W A
authors.initials: MW
authors.lastname: Skoda
authors.forename: Robert M J
authors.initials: RM
authors.lastname: Jacobs
authors.forename: Frank
authors.initials: F
authors.lastname: Schreiber
mesh_terms: D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D006801:Humans; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007477:Ions; D008670:Metals / Q000494:pharmacology*; D009010:Monte Carlo Method; D044367:Phase Transition / Q000187:drug effects*; D011506:Proteins / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012996:Solutions; D055672:Static Electricity; D015019:Yttrium / Q000494:pharmacology
chemical_list: D007477:Ions; D008670:Metals; D011506:Proteins; D012996:Solutions; C064782:yttrium chloride; D012710:Serum Albumin, Bovine; D015019:Yttrium