title: Effects of polyelectrolyte chain stiffness, charge mobility, and charge sequences on binding to proteins and micelles.
abstract: The binding affinities of polyanions for bovine serum albumin in NaCl solutions from I = 0.01-0.6 M, were evaluated on the basis of the pH at the point of incipient binding, converting each such pH(c) value into a critical protein charge Zc. Analogous values of critical charge for mixed micelles were obtained as the cationic surfactant mole fraction Yc. The data were well fitted as Yc or Zc = KI a, and values of K and a were considered as a function of normalized polymer charge densities (tau), charge mobility, and chain stiffness. Binding increased with chain flexibility and charge mobility, as expected from simulations and theory. Complex effects of tau were related to intrapolyanion repulsions within micelle-bound loops (seen in the simulations) or negative protein domain-polyanion repulsions. The linearity of Zc with radicalI at I < 0.3 M was explained by using protein electrostatic images, showing that Zc at I < 0.3 M depends on a single positive "patch"; the appearance of multiple positive domains I > 0.3 M (lower pH(c)) disrupts this simple behavior.
authors.affiliation: Department of Chemistry, Indiana Purdue University, Indianapolis, Indiana 46202, USA.
authors.forename: Christy L
authors.initials: CL
authors.lastname: Cooper
authors.forename: Ann
authors.initials: A
authors.lastname: Goulding
authors.forename: A Basak
authors.initials: AB
authors.lastname: Kayitmazer
authors.forename: Serge
authors.initials: S
authors.lastname: Ulrich
authors.forename: Serge
authors.initials: S
authors.lastname: Stoll
authors.forename: Sibel
authors.initials: S
authors.lastname: Turksen
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Yusa
authors.forename: Anil
authors.initials: A
authors.lastname: Kumar
authors.forename: Paul L
authors.initials: PL
authors.lastname: Dubin
mesh_terms: D000818:Animals; D000838:Anions / Q000737:chemistry; D001665:Binding Sites; D002417:Cattle; D004573:Electrolytes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D008956:Models, Chemical; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012965:Sodium Chloride / Q000737:chemistry; D012996:Solutions / Q000737:chemistry; D055672:Static Electricity
chemical_list: D000838:Anions; D004573:Electrolytes; D008823:Micelles; D012996:Solutions; D012710:Serum Albumin, Bovine; D012965:Sodium Chloride