title: Protein crowder charge and protein stability.
abstract: Macromolecular crowding effects arise from steric repulsions and weak, nonspecific, chemical interactions. Steric repulsions stabilize globular proteins, but the effect of chemical interactions depends on their nature. Repulsive interactions such as those between similarly charged species should reinforce the effect of steric repulsions, increasing the equilibrium thermodynamic stability of a test protein. Attractive chemical interactions, on the other hand, counteract the effect of hard-core repulsions, decreasing stability. We tested these ideas by using the anionic proteins from Escherichia coli as crowding agents and assessing the stability of the anionic test protein chymotrypsin inhibitor 2 at pH 7.0. The anionic protein crowders destabilize the test protein despite the similarity of their net charges. Thus, weak, nonspecific, attractive interactions between proteins can overcome the charge-charge repulsion and counterbalance the stabilizing effect of steric repulsion.
authors.affiliation: Department of Chemistry, ‡Department of Biochemistry and Biophysics, and §Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599-3290, United States.
authors.forename: Mohona
authors.initials: M
authors.lastname: Sarkar
authors.forename: Joe
authors.initials: J
authors.lastname: Lu
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Pielak
mesh_terms: D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D007700:Kinetics; D010455:Peptides / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D055550:Protein Stability
chemical_list: D029968:Escherichia coli Proteins; D010455:Peptides; D010940:Plant Proteins; C093336:chymotrypsin inhibitor 2