Effects of protein charge heterogeneity in protein-polyelectrolyte complexation

Park, Jeongsook M.; Muhoberac, Barry B.; Dubin, Paul L.; Xia, Jiliang

doi:10.1021/ma00027a047

Cited by 330 publications

(332 citation statements)

References 10 publications

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“…Since PAA is a weak polyelectrolyte whose titratable ionic groups have a pH-dependent degree of ionization (42,43), ␣, we can control the polymer linear charge density ( ) by fixing pH. "Type I" turbidimetric titrations were carried out by adding 40 mM CTAC to 0.50 g/L NaPAA ϩ 20 mM C 12 bidimetrically, corresponds to the onset of polymer-micelle complexation has been verified by dynamic light scattering, electrophoretic light scattering, and fluorescence spectroscopy (44,45). Surprisingly, Y c values for lower pH (5.8 -7.1) are the same as for pH 9.0, even though the degrees of ionization at lower pH are substantially lower than 1.0.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, polyelectrolyte-micelle complexation is more appropriately considered as a subset of polyelectrolyte-colloid interaction, and distinct from interactions of polymers with surfactants below the CMC. Included in the list of polyelectrolytes studied in combination with oppositely charged micelles are poly(acrylamidomethylpropanesulfonate) (PAMPS) and AMPS-acrylamide copolymers (10), poly(vinylsulfonate) (PVS) (12), poly(styrenesulfonate) (PSS) (13), poly(methacrylamidopropyltrimethylammonium chloride) (PMAPTAC) (14), sulfonated poly(vinylalcohol) (PVAS) (15), MAPTACacrylamide copolymers (16), and poly(dimethyldiallylammonium chloride) (PDADMAC) (17). All of these are strong polyelectrolytes, inasmuch as all ionic residues are fully dissociated, regardless of pH.…”

Section: Introductionmentioning

confidence: 99%

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Binding of Polycarboxylic Acids to Cationic Mixed Micelles: Effects of Polymer Counterion Binding and Polyion Charge Distribution

Yoshida

Sokhakian

Dubin

1998

Journal of Colloid and Interface Science

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Mixed micelles of cetyltrimethylammonium chloride (CTAC) and n-dodecyl hexaoxyethylene glycol monoether (C 12 E 8 ) bind to polyanions when the mole fraction of the cationic surfactant exceeds a critical value (Y c ). Y c corresponds to a critical micelle surface charge density at which polyelectrolyte will bind to this colloidal particle. Turbidimetric titrations were used to determine Y c for such cationic-nonionic micelles in the presence of acrylic acid and acrylamido-2-methylpropane sulfonate homopolymers (PAA and PAMPS, respectively) and their copolymers with acrylamide, as function of pH, ionic strength, and polyelectrolyte counterion. In 0.20 M NaCl, Y c for PAA is found to be remarkably insensitive to pH, i.e., virtually independent of the apparent polymer charge density app . On the other hand, the expected inverse relationship between Y c and app is observed either for PAA when NaCl is replaced by TMACl (tetramethylammonium chloride), or when app is manipulated using acrylic acid/acrylamide copolymers at high pH. The effective charge density of PAA is thus seen to be suppressed by specific sodium ion binding, indicating that the influence of salts on the interaction of polycarboxylic acids with colloidal particles may differ qualitatively from their effect on the analogous behavior of strong polyanions. Comparisons between homo-and copolymers of acrylic acid were carried out also to test the hypothesis that the "mobility" of charges on PAA at moderate pH (degree of ionization less than unity) could make this "annealed" polymer exhibit the behavior of a more highly charged one. The results, while consistent with this expectation, were obscured by the likely effect of copolymer sequence distributions.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Binding of Polycarboxylic Acids to Cationic Mixed Micelles: Effects of Polymer Counterion Binding and Polyion Charge Distribution

Yoshida

Sokhakian

Dubin

1998

Journal of Colloid and Interface Science

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“…Thus, the interaction of micelles with oppositely charged polyelectrolytes strongly resembles the interaction of those same polyelectrolytes with other particles of similar size and charge, for example, proteins 17 and dendrimers. 18 In all these cases, complex formation occurs when σ reaches an adequate level, and the magnitude of this value varies directly with I 1/2 and inversely with .…”

Section: Introductionmentioning

confidence: 99%

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

1998

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Pyrene-labeled hydrophobically modified polyanions were prepared by terpolymerization of sodium 2-(acrylamido)-2-methylpropanesulfonate, N-dodecylmethacrylamide (2.5-7.5 mol %), and N-(1-pyrenylmethyl)methacrylamide (1 mol %). Dynamic interactions of these polymers with mixed micelles of n-dodecyl hexa(oxyethylene) glycol monoether (C 12 E 6 ), cetyltrimethylammonium chloride (CTAC), and cetylpyridinium chloride (CPC) (quencher for pyrene fluorescence) were monitored by fluorescence quenching. The charge on the micelle was varied systematically by varying the mole fraction of CTAC (Y) in the mixed micelle. All quenching experiments were performed at Y < Y p , where Y p is a critical Y at which the polymer-micelle systems undergo macroscopic phase separation. A kinetic model was developed to estimate the binding constant (K) (where K ) k 1 /k -1 ), association rate constant (k 1 ), and lifetime of bound micelle on the polymer (residence time) (1/k -1 ) from steady-state and time-dependent fluorescence-quenching data. This analysis led to the following results: K increases with Y because both k 1 and 1/k -1 increase with Y, k 1 being more dependent on Y than 1/k -1 . K markedly increases with increasing concentration of dodecyl groups in the polymers, even at small Y, indicating a strong enhancement of polymer-micelle interactions by hydrophobic interactions. This large increase in the binding constant arises mainly from a large increase in the residence time with increase in the hydrophobe content in the polymers, 1/k -1 being much more dependent on the hydrophobe content than k 1 . The results indicate that complex formation results from hydrophobic interactions between dodecyl groups and the micelle superimposed on the effect of electrostatic force.

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“…6,7 The formation of intrapolymer complexes, while not a true phase transition, appears as a discontinuity in such properties as scattering intensity, diffusivity, and electrophoretic mobility and is designated as pH c . 5,6,8,9 While pH φ depends on polyelectrolyte molecular weight, MW, the protein and polymer concentrations (stoichiometry), pH c , are influenced solely by ionic strength. This is because pH c , corresponding to the formation of soluble complexes, is governed only by the interactions between a charged domain on the protein and its associating sequence of polyelectrolyte charges.…”

Section: Introductionmentioning

confidence: 99%

Entering and Exiting the Protein−Polyelectrolyte Coacervate Phase via Nonmonotonic Salt Dependence of Critical Conditions

2009

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Critical conditions for coacervation of poly(dimethyldiallylammonium chloride) (PDADMAC) with bovine serum albumin were determined as a function of ionic strength, pH, and protein/polyelectrolyte stoichiometry. The resultant phase boundaries, clearly defined with this narrow molecular weight distribution PDADMAC sample, showed nonmonotonic ionic strength dependence, with the pH-induced onset of coacervation (at pH φ ) occurring most readily at 20 mM NaCl. The corresponding onset of soluble complex formation, pH c , determined using highprecision turbidimetry sensitive to changes of less than 0.1% transmittance units, mirrored the ionic strength dependence of pH φ . This nonmonotonic binding behavior is attributable to simultaneous screening of short-range attraction and long-range repulsion. The similarity of pH c and pH φ was explained by the effect of salt on protein binding, and consequently on the number of bound proteins relative to that required for charge neutralization of the complex, a requirement for phase separation. Expansion of the coacervation regime with chitosan, a polycation with charge spacing similar to that of PDADMAC, could be due to either the charge mobility or chain stiffness of the former. The pH φ versus I phase boundary for PDADMAC correctly predicted entrance into and egress from the coacervation region by addition of either salt or water. The ability to induce or suppress coacervation via protein/polyelectrolyte stoichiometry r was found to be consistent with the proposed model. The results indicate that the conjoint effects of I, r, and pH on coacervation could be represented by a three-dimensional phase boundary.

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Effects of protein charge heterogeneity in protein-polyelectrolyte complexation

Cited by 330 publications

References 10 publications

Binding of Polycarboxylic Acids to Cationic Mixed Micelles: Effects of Polymer Counterion Binding and Polyion Charge Distribution

Binding of Polycarboxylic Acids to Cationic Mixed Micelles: Effects of Polymer Counterion Binding and Polyion Charge Distribution

Interaction of Pyrene-Labeled Hydrophobically Modified Polyelectrolytes with Oppositely Charged Mixed Micelles Studied by Fluorescence Quenching

Entering and Exiting the Protein−Polyelectrolyte Coacervate Phase via Nonmonotonic Salt Dependence of Critical Conditions

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