The Binding of Calcium Ions by β-Lactoglobulin Both before and after Aggregation by Heating in the Presence of Calcium Ions

Zittle, Charles A.; Dellamonica, E. S.; Rudd, Roya; Custer, J.H.

doi:10.1021/ja01574a023

Cited by 53 publications

(19 citation statements)

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“…This behavior has already been reported in ref. 39 and was explained by conformational changes of the protein structure at different pH. Also, different electrostatic interactions between the proteins due to the change in their net charge across the IEP occur.…”

Section: Surface Rheologymentioning

confidence: 99%

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Lexis

Willenbacher

2014

Soft Matter

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We have determined bulk rheology of b-lactoglobulin (BLG) foams and surface viscoelasticity of corresponding protein solutions by varying pH as well as type, valency and concentration of the added salt in a wide range. Foam rheology was characterized by the storage modulus G 0 , the apparent yield stress s y , and the critical strain g c,foam defining the cessation of the linear viscoelastic response. These quantities were determined at gas volume fractions f between 82% and 96%. Surface viscoelasticity was characterized in shear and dilation, corresponding shear and dilational moduli G 0 i , E 0 as well as the critical stress s c,surface and strain g c,surface marking the onset of non-linear response in oscillatory surface shear experiments were determined at fixed frequency. Beyond the widely accepted assumption that G 0 and s y are solely determined by the Laplace pressure within the droplets and the gas volume fraction we have found that both quantities strongly depend on corresponding interfacial properties. G 0 increases linearly with G 0 i and even stronger with E 0 , s y varies proportional to s c,surface and g c,foam scales linearly with g c,surface . Furthermore, deviations from these simple scaling laws with significantly higher reduced G 0 and s y values are observed only for foams at pH 5 and when a trivalent salt was added. Then also the dependence of these quantities on f is unusually weak and we attribute these findings to protein aggregation and structure formation across the lamellae than the dominating bulk rheology.

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Section: Surface Rheologymentioning

confidence: 99%

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Lexis

Willenbacher

2014

Soft Matter

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“…Binding of Ca 2+ to l3-lg is attributed to electrostatic reactions with ionic amino acid groups of the polypeptide chains, i.e., aspartic and glutamic acids (Zittle et al, 1957;Baumy and Brule, 1988), and it is weak compared to other milk proteins (Patocka and Jelen, 1991;Pappas and Rothwell, 1991). Fewer binding sites would be available which could be saturated with fewer Ca ions.…”

Section: Thementioning

confidence: 99%

“…PHYSICOCHEMICAL ASPECTS of interactions between calcium and proteins have been extensively studied (Zittle et al, 1957;Baumy and BrulC, 1988;Patocka and Jelen, 1991). Likewise, several studies have been performed on the binding of cations, especially Ca2+, to milk proteins under a variety of environmental conditions (Dalgleish and Parker, 1980;Parker and Dalgleish, 1981;deWit and Klarenbeek, 1984;Pappas and Rothwell, 199 1).…”

Section: Introduction Thementioning

confidence: 99%

Calcium‐Induced Destabilization of Oil‐in‐Water Emulsions Stabilized by Caseinate or by β‐Lactoglobulin

Agboola

Dalgleish

1995

Journal of Food Science

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The stability to aggregation of 20% soya oil-in-water emulsions stabilized by 0.3 to 2% sodium caseinate or P-lactoglobulin in the presence of calcium chloride solutions was studied using light scattering and electron microscopy. Stability increased with the amount of protein in the emulsion, and decreased with the concentration of added calcium. Growth of particle size with concentration of Ca2+ was more in emulsions containing lower concentrations of protein. Sodium chloride at 50 and 100 mM stabilized both systems to the'presence of calcium ions. Microstructure and light scattering showed caseinate emulsions formed clusters even at low concentrations of Ca*+ while P-lactoglobulin emulsions formed extensive strands.

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“…On heating the SPFCM dispersion there was a 36% decrease in [Ca 2+ ], but addition of /Mg in the concentration range 0-1-0-75% caused no further change in [Ca 2+ ]. Since heat-induced aggregation of /Mg seems to be dependent on the presence of Ca 2+ (Zittle et al 1957), it was felt that any /Mg aggregated in the presence of Ca 2+ would reduce the serum[Ca 2+ ] and thus increase the heat stability. However, it appears that aggregation of /Mg was prevented as a result of its complexation with /c-casein and therefore [Ca 2+ ] did not change with increasing amounts of /Mg.…”

Section: Possible Mechanism(s) For the Stabilizing Role Of Fl-lg At Pmentioning

confidence: 99%

Heat stability of milk: role of β-lactoglobulin in the pH-dependent dissociation of micellar κ-casein

Singh

Fox

1987

Journal of Dairy Research

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On heating casein micelle systems containing /Mactoglobulin (/Mg) at 90 °C for 10 min, /Mg complexed with casein micelles at pH < 6-9, probably as a result of interaction with K-casein via sulphydryl-disulphide interchange, and co-sedimented with the micelles on ultracentrifugation. Complex formation with /Mg appeared to prevent the dissociation of micellar /c-casein on heating. However, at pH ^ 69, /ccasein//Mg complexes dissociated from the micelles on heating, thus enhancing the release of micellar /c-casein. High concentrations of /Mg (^0-8%) induced coagulation at pH 7-3, essentially by promoting the dissociation of micellar /c-casein. It appeared that a sl -, a s2 -, /?-and /c-caseins dissociated from serum protein-free casein micelles to equal extents, but the presence of /Mg specifically enhanced the dissociation of /c-casein at pH values ^ 69. Micelle hydration increased slightly when casein micelles were heated in the presence of /Mg at pH 67, while at pH 7-3 /Mg decreased the degree of hydration of casein micelles. Formation of a complex between /Mg and /c-casein appeared to stabilize the micelles in the pH range 6-5-6-7, possibly via increased micellar charge or degree of hydration or by preventing the dissociation of /c-casein.It has been recognized since the work of Tessier & Rose (1964) that the pHdependence of the heat stability of milk is dependent on the formation of a disulphide-linked complex between /Mactoglobulin (/Mg) and /c-casein. Although a critical level of soluble calcium and phosphate is also necessary for the occurrence of a minimum in the heat coagulation time (HCT)-pH profile of milk, the presence of /Mg or a-lactalbumin (a-la) is essential. The HOT of serum protein-free casein micelle (SPFCM) systems is low at pH < 6-9, but increases progressively with increasing pH in the range.6-4-7-4 (Rose 1961a, b). Addition of /Mg or a-la to SPFCM systems increases heat stability in the pH range 6-4-6-8, but decreases it at pH

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The Binding of Calcium Ions by β-Lactoglobulin Both before and after Aggregation by Heating in the Presence of Calcium Ions

Cited by 53 publications

References 0 publications

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Relating foam and interfacial rheological properties of β-lactoglobulin solutions

Calcium‐Induced Destabilization of Oil‐in‐Water Emulsions Stabilized by Caseinate or by β‐Lactoglobulin

Heat stability of milk: role of β-lactoglobulin in the pH-dependent dissociation of micellar κ-casein

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