Interaction of β-casein at an emulsion interface studied by <sup>2</sup>H NMR and molecular modeling

Webb, G. A.; Belton, Peter; Gil, A. M.; Delgadillo, Ivonne; Arêas, José Alfredo Gomes; Cassiano, Marta M; Glaubitz, Clemens; Gröbner, Gerhard; Watts, Anthony

doi:10.1039/9781847551252-00193

Cited by 2 publications

(9 citation statements)

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“…Figures 1 and 2 present some conformations, displayed with program RASMOL (Sayle and Milner-White, 1995), assumed by partially and totally dephosphorylated β-CN during dynamics in aqueous medium (0 to 400 ps) and in the presence of a water/lipid interface (400 to 1000 ps). These figures show that, as observed in previous simulations of β-CN (Arêas et al, 2001;Cassiano and Arêas, 2001), both partially and totally dephosphorylated β-CN rapidly evolved from the proposed distended conformation to a more compact one, that was maintained during all the dynamics in aqueous medium. However, the behavior of the protein in the presence of the interface was different in both studied models.…”

Section: Resultssupporting

confidence: 83%

“…A new view of protein folding, recently proposed and applied to casein, suggests that the protein has both rigid structures centered on Pro residues and highly flexible elements, represented by loops and helices (Qi et al, 2001;Farrell et al, 2002). Molecular dynamics of β-CN also indicated the presence of well defined secondary structure in aqueous and lipid media (Arêas et al, 2001;Cassiano and Arêas, 2001). The modeling demonstrated that structuralization is not incompatible with inherent properties of β-CN.…”

Section: Introductionmentioning

confidence: 97%

“…In order to verify the dependence of the interfacial and structural behavior of β-CN on the SerP residues and its relationship to the mechanisms of emulsion stabilization, molecular dynamics of partially and totally dephosphorylated β-CN were performed following the same procedures previously adopted in the simulations of β-CN reported previously (Arêas et al, 2001;Cassiano and Arêas, 2001).…”

Section: Introductionmentioning

confidence: 99%

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Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Cassiano

Arêas

2003

Journal of Dairy Science

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The role of the phosphoserine residues on the dynamical and structural properties of beta-casein was studied by molecular dynamics of the protein in water/lipid interfacial regions. The initial protein structure adopted in the modeling was that proposed for bovine beta-casein A2, where the five phosphoserine residues, originally present in its primary structure, were partially or totally substituted by serine residues. The simulations revealed a dependence of the interfacial behavior of beta-casein on the phosphorylation grade. When only partially dephosphorylated, the protein showed a similar behavior as that observed for the original beta-casein reported in previous work. During dynamics, the protein migrated from the aqueous environment towards the lipid medium, and remained attached to the interface separating both media. Quite different was the dynamics of the totally dephosphorylated beta-casein, that did not perceive the interface and immersed incessantly into lipid medium. The results suggest that the phosphoserine residues appear to be, in fact, intrinsically related to the mechanisms of beta-casein emulsion stabilization.

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Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Cassiano

Arêas

2003

Journal of Dairy Science

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“…Molecular modelling clearly indicated the protein affinity for the interface, with the macromolecular dipole defining the protein orientation relative to the interface, eventually leading to a less extended conformation in a dielectrically discontinuous environment. [6][7][8] These studies also confirmed the role of the phosphate group in the -casein molecule with respect to its interfacial properties, as demonstrated experimentally. It has been reported that removal of the phosphate groups from whole casein reduces its ability to maintain emulsion integrity.…”

Section: Introductionsupporting

confidence: 66%

“…Their 3D structure and surface charge distribution are however still controversial in the literature. [5][6][7] Caseins comprise , and fractions. -casein, with 209 aminoacid residues (of which 35 prolines and no cysteine) and molecular mass of 24 kDa, has a particularly strong amphiphilic character, represented by a highly negatively charged N-terminal due to the close location of the five serine phosphates and a hydrophobic C-terminal end.…”

Section: Introductionmentioning

confidence: 99%

Rheology of decane/water and triglyceride/water emulsions stabilized by β-casein and sodium caseinate

Figueiredo

Arêas

2008

J. Braz. Chem. Soc.

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Emulsões estabilizadas por -caseína e sódio caseinato tiveram suas propriedades reológicas investigadas em função da natureza da fase oleosa, da força iônica e do pH. Fases oleosas de características estruturais distintas, a saber, decano e óleos vegetais de alto teor triglicerídico, foram ensaiadas. A emulsificação dos sistemas contendo decano foi significativamente mais efetiva do que aquela das amostras contendo triglicérides. Efeitos de pH e força iônica mostraram-se relativamente pouco importantes sobre a capacidade emulsificante da proteína. As propriedades reológicas foram marcadamente distintas em cada caso, com estruturas de caráter sólido (G´>> G´´) sendo produzidas com decano, diferentemente do que foi observado para amostras contendo triglicérides, nas quais a viscoelasticidade não foi nem mesmo aparente. A relevância de aspectos espaciais da estrutura da fase oleosa no desenvolvimento do caráter viscoelástico é discutida. Propõe-se que os fatores responsáveis pelo comportamento distinto observado residam possivelmente na interface gotícula/meio dispersante, inacessível por microscopia óptica, e guardam pouca relação com tamanho ou forma da gotícula.-Casein and sodium caseinate stabilized emulsions were produced and had their rheological properties investigated as a function of the nature of the oil phase, ionic strength and pH. Oil phases of distinct structural characteristics, namely decane and vegetable oil of high triglyceride content, were assayed. The former was much more effectively emulsified than the latter. Effects of pH and ionic strength were minor. Emulsion rheological properties were strikingly distinct in each case, with viscoelastic, solid-like structures being formed with decane (G´>> G´´), differently from what is observed for samples containing triglycerides as the oil phase, in which viscoelasticity was not even apparent. The relevance of the spatial features of the oil phase structure in the development of the emulsion viscoelastic character is discussed. Factors responding for the system distinct behaviour possibly reside at the emulsion droplet interface, unapproachable by optical microscopy, rather than on aspects related to particle size or shape.

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Interaction of β-casein at an emulsion interface studied by ²H NMR and molecular modeling

Cited by 2 publications

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Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Rheology of decane/water and triglyceride/water emulsions stabilized by β-casein and sodium caseinate

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Interaction of β-casein at an emulsion interface studied by 2H NMR and molecular modeling

Cited by 2 publications

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Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Dependence of the Interfacial Behavior of β-Casein on Phosphoserine Residues

Rheology of decane/water and triglyceride/water emulsions stabilized by β-casein and sodium caseinate

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Interaction of β-casein at an emulsion interface studied by ²H NMR and molecular modeling