Protonation of β-lactoglobulin in the presence of strong polyelectrolyte chains: a study using Monte Carlo simulation

Torres, Paola Beatriz; Bojanich, Luciano; Sánchez-Varretti, Fabricio Orlando; Ramírez-Pastor, A. J.; Quiroga, Evelina; Boeris, Valeria; Narambuena, Claudio F.

doi:10.1016/j.colsurfb.2017.09.018

Cited by 27 publications

(45 citation statements)

References 39 publications

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“…So even the net charge of the protein is of the same type as that of the polyelectrolyte chains, the polyelectrolyte brush is still capable of adsorbing a certain amount of proteins into its layer . And the main driving force for the adsorption of proteins under this circumstance is generally considered to be counterion release force based on experimental and theoretical studies . However, it is worth noting that the electrostatic force also plays an important role in the controllable immobilization of proteins onto polyelectrolytes carriers.…”

Section: Introductionmentioning

confidence: 99%

Controllable immobilization of proteins in quenched spherical polyelectrolyte brushes as observed by fluorescence spectroscopy and small angle X‐ray scattering

Zhao

et al. 2018

J Polym Sci B Polym Phys

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The immobilization of lysozymes (pI = 11) onto anionic spherical polyelectrolyte brushes (SPB) which consist of a solid polystyrene core and a densely grafted poly(styrene sulfonate) (PSS) shell was systematically studied by fluorescence spectroscopy and small angle X‐ray scattering. Results show that the capture of lysozyme by PSS brush is a dynamic process, which involves a quick agglomeration stage and a slow rearrangement one. And lysozyme inclines to immobilize in the inner layer of the brush, and saturation of lysozyme adsorption onto the SPB is gradually reached as the protein concentration increases, proceeding from the inside to the outside of the brush layers. As increasing the pH and ionic strength, the lysozyme previously adsorbed will be partially released and migrate from the inner to the outer layer of SPB. Last competitive adsorption tests between lysozyme and BSA or β‐glucosidase were performed, indicating that besides electrostatic interaction counterion release force also plays an important role in protein adsorption. SPB was proved to be ideal candidate for controllable immobilization of protein, which can be extended into various applications, such as drug delivery and protein separation. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1577–1588

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Section: Introductionmentioning

confidence: 99%

Controllable immobilization of proteins in quenched spherical polyelectrolyte brushes as observed by fluorescence spectroscopy and small angle X‐ray scattering

Zhao

et al. 2018

J Polym Sci B Polym Phys

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“…La cadena de polielectrolito fue modelada como un grupo de perlas cargadas (o monómeros) enlazados formando una cadena lineal, ver figura 1B. Cada esfera fue representada como una esfera rígida con su correspondiente carga eléctrica embebida en el centro y separadas una distancia 0 (P. B. Torres, Quiroga, Ramirez-Pastor, Boeris, & Narambuena, 2019; P. Torres et al, 2017).…”

Section: Desarrollounclassified

“…Se adopta como criterio para considerar un monómero adsorbido que la distancia cumpla < , donde = 0.5 es el radio de corte. Este simple criterio de distancia fue utilizado para cuantificar la condensación de las cadenas del PE, mostrando una excelente coincidencia con los datos experimentales (P. Torres et al, 2017).…”

Section: Desarrollounclassified

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Interacción de β-lactoglobulina y polielectrolitos fuertes: un estudio computacional

Torres

Narambuena²,

Quiroga³

2020

AJEA

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La β-lactoglobulina (BLG) es la principal proteína del suero lácteo, se destaca por su elevado valor nutricional. Se busca purificar la proteína mediante métodos sencillos, rápidos y económicos para su aplicación a escala industrial, ya que en la actualidad los métodos tradicionales son costosos para las PYMES lácteas. Se pueden obtener concentrados de la proteína BLG mediante la formación de un complejo con un polielectrolito (PE). Estos complejos en ciertas condiciones son insolubles y fácilmente separables. En el presente trabajo estudiamos este proceso mediante simulaciones computacionales a nivel molecular. La metodología utilizada consiste en representar a la proteína y el polielectrolito con modelos de grano grueso con un número mínimo de parámetros que permiten reproducir la esencia fisicoquímica del proceso. Se estudió la formación del complejo a distintos valores de pH usando simulación de Monte Carlo. La interacción entre proteína-PE fue cuantificada por un criterio estructural para medir la adsorción del PE en la superficie de la proteína. Se cuantifican la cantidad de pares iónicos (monómero cargado y residuo cargado). Los resultados mostraron que la interacción de la proteína con un polianión se veía favorecida a valores de pH por debajo del punto isoeléctrico (pI) de la proteína. Por otro lado, la formación del complejo entre proteína y policatión comienza a valores de pH por debajo del punto isoeléctrico es decir “del lado equivocado”. Esta formación de complejo del lado equivocado del pI, fue debida al mecanismo de regulación de carga, donde la reversión de la carga es más pronunciada del lado izquierdo del punto isoeléctrico. Los grupos ácidos glutámico y aspártico juegan un rol clave en la reversión de carga.

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“…In a wide range of situations, the physicochemical behaviour of charged polymers cannot be understood without the presence of CR. A few examples would be the stability of colloidal systems [3], protein-surface [4,5], protein-protein [6,7] and protein-polyelectrolyte [8,9] interactions, nano-particle coating [10], supramolecular chemistry [11,12], ligand-receptor binding in biochemistry [13][14][15], drug delivery [16], protein folding [17], among many others.…”

Section: Introductionmentioning

confidence: 99%

Role of Charge Regulation and Fluctuations in the Conformational and Mechanical Properties of Weak Flexible Polyelectrolytes

et al. 2019

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This work addresses the role of charge regulation (CR) and the associated fluctuations in the conformational and mechanical properties of weak polyelectrolytes. Due to CR, changes in the pH-value modifies the average macromolecular charge and conformational equilibria. A second effect is that, for a given average charge per site, fluctuations can alter the intensity of the interactions by means of correlation between binding sites. We investigate both effects by means of Monte Carlo simulations at constant pH-value, so that the charge is a fluctuating quantity. Once the average charge per site is available, we turn off the fluctuations by assigning the same average charge to every site. A constant charge MC simulation is then performed. We make use of a model which accounts for the main fundamental aspects of a linear flexible polyelectrolyte that is, proton binding, angle internal rotation, bond stretching and bending. Steric excluded volume and differentiated treatment for short-range and long-range interactions are also included. This model can be regarded as a kind of “minimal” in the sense that it contains a minimum number of parameters but still preserving the atomistic detail. It is shown that, if fluctuations are activated, gauche state bond probabilities increase and the persistence length decreases, so that the polymer becomes more folded. Macromolecular stretching is also analyzed in presence of CR (the charge depends on the applied force) and without CR (the charge is fixed to the value at zero force). The analysis of the low force scaling behavior concludes that Pincus exponent becomes pH-dependent. Both, with and without CR, a transition from 1/2 at high pH-values (phantom chain) to 3/5 at low pH-values (Pincus regime) is observed. Finally, the intermediate force stretching regime is investigated. It is found that CR induces a moderate influence in the force-extension curves and persistence length (which in this force regime becomes force-dependent). It is thus concluded that the effect of CR on the stretching curves is mainly due to the changes in the average charge at zero force. It is also found that, for the cases studied, the effect of steric excluded volume is almost irrelevant compared to electrostatic interactions.

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Protonation of β-lactoglobulin in the presence of strong polyelectrolyte chains: a study using Monte Carlo simulation

Cited by 27 publications

References 39 publications

Controllable immobilization of proteins in quenched spherical polyelectrolyte brushes as observed by fluorescence spectroscopy and small angle X‐ray scattering

Controllable immobilization of proteins in quenched spherical polyelectrolyte brushes as observed by fluorescence spectroscopy and small angle X‐ray scattering

Interacción de β-lactoglobulina y polielectrolitos fuertes: un estudio computacional

Role of Charge Regulation and Fluctuations in the Conformational and Mechanical Properties of Weak Flexible Polyelectrolytes

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