Effects of Polyelectrolyte Chain Stiffness, Charge Mobility, and Charge Sequences on Binding to Proteins and Micelles

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 pHc value into a critical protein charge Z c. Analogous values of critical charge for mixed micelles were...

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Bibliographic Details
Published in:Biomacromolecules 2006-04, Vol.7 (4), p.1025-1035
Main Authors: Cooper, Christy L, Goulding, Ann, Kayitmazer, A. Basak, Ulrich, Serge, Stoll, Serge, Turksen, Sibel, Yusa, Shin-ichi, Kumar, Anil, Dubin, Paul L
Format: Article
Language:English
Subjects:
Animals
Anions - chemistry
Applied sciences
Binding Sites
Cattle
Electrolytes - chemistry
Exact sciences and technology
Hydrogen-Ion Concentration
Micelles
Models, Chemical
Organic polymers
Physicochemistry of polymers
Properties and characterization
Serum Albumin, Bovine - chemistry
Sodium Chloride - chemistry
Solution and gel properties
Solutions - chemistry
Static Electricity
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Summary: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 pHc value into a critical protein charge Z c. Analogous values of critical charge for mixed micelles were obtained as the cationic surfactant mole fraction Y c. The data were well fitted as Y c or Z c = KI   a , and values of K and a were considered as a function of normalized polymer charge densities (τ), charge mobility, and chain stiffness. Binding increased with chain flexibility and charge mobility, as expected from simulations and theory. Complex effects of τ were related to intrapolyanion repulsions within micelle-bound loops (seen in the simulations) or negative protein domain−polyanion repulsions. The linearity of Z c with √I at I < 0.3 M was explained by using protein electrostatic images, showing that Z c at I < 0.3 M depends on a single positive “patch”; the appearance of multiple positive domains I > 0.3 M (lower pHc) disrupts this simple behavior.
ISSN:1525-7797
1526-4602
DOI:10.1021/bm050592j