Non-native States of Bovine Beta-Lactoglobulin Induced by Acetonitrile: pH-Dependent Unfolding of the Two Genetic Variants A and B

Naqvi, Zainab; Ahmad, Ejaz; Khan, Rizwan Hasan; Saleemuddin, M.

doi:10.1007/s12013-012-9466-7

Cited by 10 publications

(6 citation statements)

References 54 publications

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“…This may suggests that a less acidic pH solution provides a more suitable environment to enhance interactions between a-La and Lys (Jindal & Naeem, 2013). Naqvi et al (2013) studied the intrinsic fluorescence of b-lactoglobulin and claimed that, at pH 9.0, the protein showed higher fluorescence intensity than at pH 7.0, while Diniz et al (2014) found higher fluorescence intensity at pH 6.5 than at pH 3.5, which agrees with our data. These results, together with those obtained by CD, confirmed that association between a-La and Lys occurs under the conditions analyzed here, and that such association is affected by pH, temperature and heating time.…”

Section: Fluorescence Spectroscopysupporting

confidence: 90%

Design of bio-based supramolecular structures through self-assembly of α-lactalbumin and lysozyme

Monteiro

Pereira

et al. 2016

Food Hydrocolloids

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Bovine a-lactalbumin (a-La) and lysozyme (Lys), two globular proteins with highly homologous tertiary structures and opposite isoelectric points, were used to produce bio-based supramolecular structures under various pH values (3, 7 and 11), temperatures (25, 50 and 75 C) and times (15, 25 and 35 min) of heating. Isothermal titration calorimetry experiments showed protein interactions and demonstrated that structures were obtained from the mixture of a-La/Lys in molar ratio of 0.546. Structures were characterized in terms of morphology by transmission electron microscopy (TEM) and dynamic light scattering (DLS), conformational structure by circular dichroism and intrinsic fluorescence spectroscopy and stability by DLS. Results have shown that protein conformational structure and intermolecular interactions are controlled by the physicochemical conditions applied. The increase of heating temperature led to a significant decrease in size and polydispersity (PDI) of a-LaeLys supramolecular structures, while the increase of heating time, particularly at temperatures above 50 C, promoted a significant increase in size and PDI. At pH 7 supramolecular structures were obtained at microscale e confirmed by optical microscopy e displaying also a high PDI (i.e. > 0.4). The minimum size and PDI (61 ± 2.3 nm and 0.14 ± 0.03, respectively) were produced at pH 11 for a heating treatment of 75 C for 15 min, thus suggesting that these conditions could be considered as critical for supramolecular structure formation. Its size and morphology were confirmed by TEM showing a well-defined spherical form. Structures at these conditions showed to be stable at least for 30 or 90 days, when stored at 25 or 4 C, respectively. Hence, a-LaeLys supramolecular structures showed properties that indicate that they are a promising delivery system for food and pharmaceutical applications.

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Section: Fluorescence Spectroscopysupporting

confidence: 90%

Design of bio-based supramolecular structures through self-assembly of α-lactalbumin and lysozyme

Monteiro

Pereira

et al. 2016

Food Hydrocolloids

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“…This observation suggests that the less acidic pH solution provides a more suitable environment for the structures when they are exposed to higher temperatures for a longer time. Naqvi et al (2013) studied the intrinsic fluorescence of β-lactoglobulin and observed that at pH 9.0, the protein showed higher fluorescence intensity than at pH 7.0, in accordance with our results. Fig.…”

Section: Fluorescence Spectroscopysupporting

confidence: 88%

Production, characterization and foamability of α-lactalbumin/glycomacropeptide supramolecular structures

Diniz¹,

Coimbra²,

Teixeira³

et al. 2014

Food Research International

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The study of protein interactions has generated great interest in the food industry. Therefore, research on new supramolecular structures shows promise. Supramolecular structures of the whey proteins α-lactalbumin and glycomacropeptide were produced under varying heat treatments (25 to 75°C) and acidic conditions (pH3.5 to 6.5). Isothermal titration calorimetry experiments showed protein interactions and demonstrated that this is an enthalpically driven process. Supramolecular protein structures in aqueous solutions were characterized by circular dichroism and intrinsic fluorescence spectroscopy. Additional photon correlation spectroscopy experiments showed that the size distribution of the structures ranged from 4 to 3545nm among the different conditions. At higher temperatures, lower pH increased particle size. The foamability of the supramolecular protein structures was evaluated. Analysis of variance and analysis of regression for foaming properties indicated that the two-factor interactions between pH and temperature exhibited a significant effect on the volume and stability of the foam.

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“…Some aggregation was observed in purified β-LG, which could be explained by interactions with the acetonitrile in the HPLC eluent used (Chen et al, 2007;Dhamole et al, 2010). Acetonitrile can induce structural changes in the β-LG genetic variants, A and B at pH 7, such as aggregation and unfolding (Naqvi et al, 2013). In our CD spectra, the content of β-sheet was lowest in untreated β-LG.…”

Section: Discussionmentioning

confidence: 66%

“…The native variants A and B of β-LG, with a predominantly β-sheet structure, showed an intense negative band at 216 nm (Dong et al, 1996). As the acetonitrile concentration was increased, the CD spectral signature was noticeably transformed from β-sheet to typical α-helix structure (Naqvi et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Structure and allergenicity assessments of bovine β-lactoglobulin treated by sonication-assisted irradiation

Yang

Zou

et al. 2020

Journal of Dairy Science

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Bovine β-lactoglobulin (β-LG) is recognized as a major allergen in milk. This study aimed to investigate ultrasound-assisted irradiation for reducing the allergenicity of β-LG, since irradiation can reduce the allergenicity of cow milk proteins and ultrasound can improve the quality of milk. The structural changes induced in high purity β-LG, treated by irradiation, with or without sonication, were characterized by native PAGE, circular dichroism spectroscopy, and fluorescence spectroscopy. The changes in allergenicity were measured by IgE binding capacity to, and inflammatory mediator secretion by, human basophil KU812 cells. Surface hydrophobicity was reduced and aggregation of β-LG increased after treatment by irradiation, both with and without sonication. The IgE binding capacity and release of inflammatory mediators were reduced significantly and the reduction induced by irradiation before sonication was the greatest, suggesting that irradiation after sonication can be a safe and effective method to reduce the allergenicity of β-LG in dairy processing.

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Non-native States of Bovine Beta-Lactoglobulin Induced by Acetonitrile: pH-Dependent Unfolding of the Two Genetic Variants A and B

Cited by 10 publications

References 54 publications

Design of bio-based supramolecular structures through self-assembly of α-lactalbumin and lysozyme

Design of bio-based supramolecular structures through self-assembly of α-lactalbumin and lysozyme

Production, characterization and foamability of α-lactalbumin/glycomacropeptide supramolecular structures

Structure and allergenicity assessments of bovine β-lactoglobulin treated by sonication-assisted irradiation

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