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Gai N, Uniacke-Lowe T, O’Regan J, Faulkner H, Kelly AL. Effect of Protein Genotypes on Physicochemical Properties and Protein Functionality of Bovine Milk: A Review. Foods 2021; 10:2409. [PMID: 34681458 PMCID: PMC8535582 DOI: 10.3390/foods10102409] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 12/05/2022] Open
Abstract
Milk protein comprises caseins (CNs) and whey proteins, each of which has different genetic variants. Several studies have reported the frequencies of these genetic variants and the effects of variants on milk physicochemical properties and functionality. For example, the C variant and the BC haplotype of αS1-casein (αS1-CN), β-casein (β-CN) B and A1 variants, and κ-casein (κ-CN) B variant, are favourable for rennet coagulation, as well as the B variant of β-lactoglobulin (β-lg). κ-CN is reported to be the only protein influencing acid gel formation, with the AA variant contributing to a firmer acid curd. For heat stability, κ-CN B variant improves the heat resistance of milk at natural pH, and the order of heat stability between phenotypes is BB > AB > AA. The A2 variant of β-CN is more efficient in emulsion formation, but the emulsion stability is lower than the A1 and B variants. Foaming properties of milk with β-lg variant B are better than A, but the differences between β-CN A1 and A2 variants are controversial. Genetic variants of milk proteins also influence milk yield, composition, quality and processability; thus, study of such relationships offers guidance for the selection of targeted genetic variants.
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Affiliation(s)
- Nan Gai
- School of Food and Nutritional Sciences, University College Cork, T12 YN60 Cork, Ireland; (N.G.); (T.U.-L.)
| | - Therese Uniacke-Lowe
- School of Food and Nutritional Sciences, University College Cork, T12 YN60 Cork, Ireland; (N.G.); (T.U.-L.)
| | - Jonathan O’Regan
- Nestlé Development Centre Nutrition, Wyeth Nutritionals Ireland, Askeaton, Co., V94 E7P9 Limerick, Ireland; (J.O.); (H.F.)
| | - Hope Faulkner
- Nestlé Development Centre Nutrition, Wyeth Nutritionals Ireland, Askeaton, Co., V94 E7P9 Limerick, Ireland; (J.O.); (H.F.)
| | - Alan L. Kelly
- School of Food and Nutritional Sciences, University College Cork, T12 YN60 Cork, Ireland; (N.G.); (T.U.-L.)
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2
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Famelart MH, Croguennec T, Sevrin T. Optimisation of microparticle formation by dry heating of whey proteins. J FOOD ENG 2021. [DOI: 10.1016/j.jfoodeng.2020.110221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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3
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Yoshida K, Zenin T, Fujiyoshi A, Sanada Y, Yamaguchi T, Murata K, Takata SI, Hiroi K, Takekiyo T, Yoshimura Y. The effect of alkyl ammonium ionic liquids on thermal denaturation aggregation of β-lactoglobulin. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111477] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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4
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Swiatek S, Komorek P, Jachimska B. Adsorption of β-lactoglobulin A on gold surface determined in situ by QCM-D measurements. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.01.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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5
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Leeb E, Haller N, Kulozik U. Effect of pH on the reaction mechanism of thermal denaturation and aggregation of bovine β-lactoglobulin. Int Dairy J 2018. [DOI: 10.1016/j.idairyj.2017.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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6
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Jachimska B, Świątek S, Loch JI, Lewiński K, Luxbacher T. Adsorption effectiveness of β-lactoglobulin onto gold surface determined by quartz crystal microbalance. Bioelectrochemistry 2018; 121:95-104. [PMID: 29413868 DOI: 10.1016/j.bioelechem.2018.01.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Revised: 12/20/2017] [Accepted: 01/22/2018] [Indexed: 12/30/2022]
Abstract
Bovine β-lactoglobulin (LGB) is a transport protein that can bind to its structure hydrophobic bioactive molecules. Due to the lack of toxicity, high stability and pH-dependent molecular binding mechanism, lactoglobulin can be used as a carrier of sparingly soluble drugs. Dynamic light scattering has confirmed LGB's tendency to create oligomeric forms. The hydrodynamic diameter of LGB molecules varies from 4 nm to 6 nm in the pH range of 2-10 and ionic strength I = 0.001-0.15 M, which corresponds to the presence of mono or dimeric LGB forms. The LGB zeta potential varies from 26.5 mV to -33.3 mV for I = 0.01 M and from 13.3 mV to -16 mV for I = 0.15 M in the pH range of 2-10. The isoelectric point is at pH 4.8. As a result of strong surface charge compensation, the maximum effective ionization degree of the LGB molecule is 35% for ionic strength I = 0.01 M and 22% for I = 0.15 M. The effectiveness of adsorption is linked with the properties of the protein, as well as those of the adsorption surface. The functionalization of gold surfaces with β-lactoglobulin (LGB) was studied using a quartz crystal microbalance with energy dissipation monitoring (QCM-D). The effectiveness of LGB adsorption correlates strongly with a charge of gold surface and the zeta potential of the molecule. The greatest value of the adsorbed mass was observed in the pH range in which LGB has a positive zeta potential values, below pH 4.8. This observation shows that electrostatic interactions play a dominant role in LGB adsorption on gold surfaces. Based on the adsorbed mass, protein orientation on gold surfaces was determined. The preferential side-on orientation of LGB molecules observed in the adsorption layer is consistent with the direction of the molecule dipole momentum determined by molecular dynamics simulations of the protein (MD). The use of the QCM-D method also allowed us to determine the effectiveness of adsorption of LGB on gold surface. Knowing the mechanism of LGB adsorption is significant importance for determining the optimum conditions for immobilizing this protein on solid surfaces. As β-lactoglobulin is a protein that binds various ligands, the binding properties of immobilized β-lactoglobulin can be used to design controlled protein structures for biomedical applications.
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Affiliation(s)
- B Jachimska
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Niezapominajek 8, 30-239 Cracow, Poland.
| | - S Świątek
- Jerzy Haber Institute of Catalysis and Surface Chemistry, PAS, Niezapominajek 8, 30-239 Cracow, Poland
| | - J I Loch
- Jagiellonian University, Faculty of Chemistry, Department of Crystal Chemistry and Crystal Physics, Biocrystallography Group, Ingardena 3, 30-060 Cracow, Poland
| | - K Lewiński
- Jagiellonian University, Faculty of Chemistry, Department of Crystal Chemistry and Crystal Physics, Biocrystallography Group, Ingardena 3, 30-060 Cracow, Poland
| | - T Luxbacher
- Anton Paar GmbH, Anton-Paar-Strasse 20, 8045 Graz, Austria
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Interfacial shear rheology of β-lactoglobulin—Bovine submaxillary mucin layers adsorbed at air/water interface. Int J Biol Macromol 2017; 102:857-867. [DOI: 10.1016/j.ijbiomac.2017.04.063] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 03/25/2017] [Accepted: 04/15/2017] [Indexed: 11/18/2022]
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8
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Cheison SC, Kulozik U. Impact of the environmental conditions and substrate pre-treatment on whey protein hydrolysis: A review. Crit Rev Food Sci Nutr 2017; 57:418-453. [PMID: 25976220 DOI: 10.1080/10408398.2014.959115] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Proteins in solution are subject to myriad forces stemming from interactions with each other as well as with the solvent media. The role of the environmental conditions, namely pH, temperature, ionic strength remains under-estimated yet it impacts protein conformations and consequently its interaction with, and susceptibility to, the enzyme. Enzymes, being proteins are also amenable to the environmental conditions because they are either activated or denatured depending on the choice of the conditions. Furthermore, enzyme specificity is restricted to a narrow regime of optimal conditions while opportunities outside the optimum conditions remain untapped. In addition, the composition of protein substrate (whether mixed or single purified) have been underestimated in previous studies. In addition, protein pre-treatment methods like heat denaturation prior to hydrolysis is a complex phenomenon whose progression is influenced by the environmental conditions including the presence or absence of sugars like lactose, ionic strength, purity of the protein, and the molecular structure of the mixed proteins particularly presence of free thiol groups. In this review, we revisit protein hydrolysis with a focus on the impact of the hydrolysis environment and show that preference of peptide bonds and/or one protein over another during hydrolysis is driven by the environmental conditions. Likewise, heat-denaturing is a process which is dependent on not only the environment but the presence or absence of other proteins.
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Affiliation(s)
| | - Ulrich Kulozik
- b Chair for Food Process Engineering and Dairy Technology Department , ZIEL Technology Section, Technische Universität München , Weihenstephaner Berg 1, Freising , Germany
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9
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Dombrowski J, Johler F, Warncke M, Kulozik U. Correlation between bulk characteristics of aggregated β-lactoglobulin and its surface and foaming properties. Food Hydrocoll 2016. [DOI: 10.1016/j.foodhyd.2016.05.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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10
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Dombrowski J, Dechau J, Kulozik U. Multiscale approach to characterize bulk, surface and foaming behavior of casein micelles as a function of alkalinisation. Food Hydrocoll 2016. [DOI: 10.1016/j.foodhyd.2015.12.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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11
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Steinhauer T, Marx M, Bogendörfer K, Kulozik U. Membrane fouling during ultra- and microfiltration of whey and whey proteins at different environmental conditions: The role of aggregated whey proteins as fouling initiators. J Memb Sci 2015. [DOI: 10.1016/j.memsci.2015.04.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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12
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Ioannou J, Donald A, Tromp R. Characterising the secondary structure changes occurring in high density systems of BLG dissolved in aqueous pH 3 buffer. Food Hydrocoll 2015. [DOI: 10.1016/j.foodhyd.2014.12.027] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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A Population Balance Model integrating some specificities of the β-lactoglobulin thermally-induced aggregation. J FOOD ENG 2015. [DOI: 10.1016/j.jfoodeng.2014.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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14
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Blayo C, Puentes-Rivas D, Picart-Palmade L, Chevalier-Lucia D, Lange R, Dumay E. Binding of retinyl acetate to whey proteins or phosphocasein micelles: Impact of pressure-processing on protein structural changes and ligand embedding. Food Res Int 2014. [DOI: 10.1016/j.foodres.2014.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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15
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Mitropoulos V, Mütze A, Fischer P. Mechanical properties of protein adsorption layers at the air/water and oil/water interface: a comparison in light of the thermodynamical stability of proteins. Adv Colloid Interface Sci 2014; 206:195-206. [PMID: 24332621 DOI: 10.1016/j.cis.2013.11.004] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 09/07/2013] [Accepted: 11/06/2013] [Indexed: 01/18/2023]
Abstract
Over the last decades numerous studies on the interfacial rheological response of protein adsorption layers have been published. The comparison of these studies and the retrieval of a common parameter to compare protein interfacial activity are hampered by the fact that different boundary conditions (e.g. physico-chemical, instrumental, interfacial) were used. In the present work we review previous studies and attempt a unifying approach for the comparison between bulk protein properties and their adsorption films. Among many common food grade proteins we chose bovine serum albumin, β-lactoglobulin and lysozyme for their difference in thermodynamic stability and studied their adsorption at the air/water and limonene/water interface. In order to achieve this we have i) systematically analyzed protein adsorption kinetics in terms of surface pressure rise using a drop profile analysis tensiometer and ii) we addressed the interfacial layer properties under shear stress using an interfacial shear rheometer under the same experimental conditions. We could show that thermodynamically less stable proteins adsorb generally faster and yield films with higher shear rheological properties at air/water interface. The same proteins showed an analog behavior when adsorbing at the limonene/water interface but at slower rates.
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Assessment of stability of binary sweetener blend (aspartame x acesulfame-K) during storage in whey lemon beverage. Journal of Food Science and Technology 2014; 50:770-6. [PMID: 24425980 DOI: 10.1007/s13197-011-0386-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 04/07/2011] [Accepted: 04/15/2011] [Indexed: 10/18/2022]
Abstract
In the present study, artificial sweeteners-aspartame, acesulfame-K and binary sweetener blend of aspartame x acesulfame-K were assessed for stability during storage in whey lemon beverage. A solid phase extraction method using C18 cartridges was standardized for the isolation of aspartame, acesulfame-K and their degradation products in whey lemon beverage. HPLC analytical conditions were standardized over C18 column for simultaneous separation of multiple sweeteners and their degradation products in sample isolates. Storage studies revealed that increase in acidity and viscosity and decrease in pH and ascorbic acid content of artificially sweetened whey lemon beverage samples were similar to the changes occurring in control samples during storage. Analysis using HPLC showed that aspartame (added either singly or in a blend) and acesulfame-K (added in a blend) were stable in whey lemon beverage under refrigerated condition for 15 days.
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17
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Yoshida K, Fukushima Y, Yamaguchi T. A study of alcohol and temperature effects on aggregation of β-lactoglobulin by viscosity and small-angle X-ray scattering measurements. J Mol Liq 2014. [DOI: 10.1016/j.molliq.2013.06.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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18
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Effect of calcium chloride and moderate shear on β-lactoglobulin aggregation in processing-like conditions. J FOOD ENG 2013. [DOI: 10.1016/j.jfoodeng.2012.09.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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19
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Haug I, Carlsen AM, Vegarud G, Langsrud T, Draget K. Textural Properties of Beta-lactoglobulin - Sodium Alginate Mixed Gels at Large Scale Deformation. J Texture Stud 2012; 44:56-65. [DOI: 10.1111/j.1745-4603.2012.00365.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 06/18/2012] [Indexed: 11/28/2022]
Affiliation(s)
- I.J. Haug
- Norwegian Biopolymer Laboratory (NOBIPOL); Institute of Biotechnology; Norwegian University of Science and Technology (NTNU); N-7491; Trondheim; Norway
| | - A.-M.H. Carlsen
- Norwegian Biopolymer Laboratory (NOBIPOL); Institute of Biotechnology; Norwegian University of Science and Technology (NTNU); N-7491; Trondheim; Norway
| | - G.E. Vegarud
- Institute of Chemistry, Biotechnology and Food Science (IKBM); Norwegian University of Life science (UMB); Aas; Norway
| | - T. Langsrud
- Institute of Chemistry, Biotechnology and Food Science (IKBM); Norwegian University of Life science (UMB); Aas; Norway
| | - K.I. Draget
- Norwegian Biopolymer Laboratory (NOBIPOL); Institute of Biotechnology; Norwegian University of Science and Technology (NTNU); N-7491; Trondheim; Norway
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20
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Deng X, Hahne T, Schröder S, Redweik S, Nebija D, Schmidt H, Janssen O, Lachmann B, Wätzig H. The challenge to quantify proteins with charge trains due to isoforms or conformers. Electrophoresis 2011; 33:263-9. [DOI: 10.1002/elps.201100321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 07/30/2011] [Accepted: 08/05/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Xi Deng
- Institute of Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Thomas Hahne
- Institute of Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Simone Schröder
- Institute of Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Sabine Redweik
- Institute of Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
| | - Dashnor Nebija
- Department of Medicinal and Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Hendrik Schmidt
- Laboratory for Molecular Immunology, Institute for Immunology, University Hospital Schleswig‐Holstein, Kiel, Germany
| | - Ottmar Janssen
- Laboratory for Molecular Immunology, Institute for Immunology, University Hospital Schleswig‐Holstein, Kiel, Germany
| | - Bodo Lachmann
- Department of Medicinal and Pharmaceutical Chemistry, University of Vienna, Vienna, Austria
| | - Hermann Wätzig
- Institute of Pharmaceutical Chemistry, Technische Universität Braunschweig, Braunschweig, Germany
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21
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Chelulei Cheison S, Brand J, Leeb E, Kulozik U. Analysis of the effect of temperature changes combined with different alkaline pH on the β-lactoglobulin trypsin hydrolysis pattern using MALDI-TOF-MS/MS. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:1572-1581. [PMID: 21319805 DOI: 10.1021/jf1039876] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Temperature and pH influence the conformation of the whey protein β-lactoglobulin (β-Lg) monomer, dimer, and octamer formation, its denaturation, and solubility. Most hydrolyses have been reported at trypsin (EC 3.4.21.4) optimum conditions (pH 7.8 and 37 °C), while the hydrolysate mass spectrometry was largely limited to peptides with <4 kDa. There are few reports on trypsin peptide release patterns away from optimum. This work investigated the influence of alkaline (8.65 and 9.5) and optimum (7.8) pH at different temperatures (25, 37.5, and 50 °C) on β-Lg (7.5%, w/v) hydrolysis. Sample aliquots were drawn out before the addition of trypsin (blank sample) and at various time intervals (15 s to 10 min) thereafter. Matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry (MALDI-TOF-MS/MS) was used to monitor peptide evolution over time with the use of two matrixes: α-cyano-4-hydroxycinnamic acid (HCCA) and 2.5-dihydroxyacetophenone (DHAP). Mass analysis showed that the N- and C-terminals (Lys(8)-Gly(9), Lys(100)-Lys(101), Arg(124)-Thr(125), Lys(141)-Ala(142), and Arg(148)-Leu(149)) of β-Lg were cleaved early (15 s) implying the ease of trypsinolysis at the exposed terminals. Hydrolyses at 25 °C and pH 7.8 as well as at 50 °C and pH 9.5 were slowed down and ordered. Nonspecific chymotrypsin-like behavior occurred more at higher temperatures (50 °C) than at lower ones (25 and 37.5 °C). In addition to our earlier work in the acid pH region, it can be concluded that there is potential for controlled hydrolysis outside the trypsin optimum, where different target peptides with predictable biofunctionalities could be produced.
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Affiliation(s)
- Seronei Chelulei Cheison
- Zentralinstitut für Ernährungs- und Lebensmittelforschung (ZIEL)-Junior Research Group: Bioactive Peptides and Protein Technology, Technische Universität München , Weihenstephaner Berg 1, D-85354 Freising, Germany.
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22
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Influence of buffer type and concentration on the peptide composition of trypsin hydrolysates of β-lactoglobulin. Food Chem 2011. [DOI: 10.1016/j.foodchem.2010.08.047] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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23
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Influence of hydrolysis temperature and pH on the selective hydrolysis of whey proteins by trypsin and potential recovery of native alpha-lactalbumin. Int Dairy J 2011. [DOI: 10.1016/j.idairyj.2010.09.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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24
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Thermally-induced protein–polyphenol co-assemblies: beta lactoglobulin-based nanocomplexes as protective nanovehicles for EGCG. Food Hydrocoll 2010. [DOI: 10.1016/j.foodhyd.2010.03.015] [Citation(s) in RCA: 247] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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25
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The dynamics of heat gelation of casein glycomacropeptide – β-lactoglobulin mixtures as affected by interactions in the aqueous phase. Int Dairy J 2010. [DOI: 10.1016/j.idairyj.2009.11.016] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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26
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Yoshida K, Yamaguchi T, Osaka N, Endo H, Shibayama M. A study of alcohol-induced gelation of β-lactoglobulin with small-angle neutron scattering, neutron spin echo, and dynamic light scattering measurements. Phys Chem Chem Phys 2010; 12:3260-9. [DOI: 10.1039/b920187d] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Electrostatic effects on β-lactoglobulin transitions during heat denaturation as studied by differential scanning calorimetry. Food Hydrocoll 2009. [DOI: 10.1016/j.foodhyd.2009.06.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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28
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Aguilera JM, Stanley DW. The microstructure of food protein assemblies. FOOD REVIEWS INTERNATIONAL 2009. [DOI: 10.1080/87559129309540977] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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29
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Grácia-Juliá A, René M, Cortés-Muñoz M, Picart L, López-Pedemonte T, Chevalier D, Dumay E. Effect of dynamic high pressure on whey protein aggregation: A comparison with the effect of continuous short-time thermal treatments. Food Hydrocoll 2008. [DOI: 10.1016/j.foodhyd.2007.05.017] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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30
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Osaka N, Takata SI, Suzuki T, Endo H, Shibayama M. Comparison of heat- and pressure-induced gelation of β-lactoglobulin aqueous solutions studied by small-angle neutron and dynamic light scattering. POLYMER 2008. [DOI: 10.1016/j.polymer.2008.04.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Sakurai K, Goto Y. Principal component analysis of the pH-dependent conformational transitions of bovine beta-lactoglobulin monitored by heteronuclear NMR. Proc Natl Acad Sci U S A 2007; 104:15346-51. [PMID: 17878316 PMCID: PMC2000507 DOI: 10.1073/pnas.0702112104] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
To clarify the pH-dependent conformational transitions of proteins, we propose an approach in which structural changes monitored by heteronuclear sequential quantum correlation (HSQC) spectroscopy were analyzed by using a principal component analysis (PCA). We use bovine beta-lactoglobulin, a protein widely used in protein folding studies, as a target. First, we measured HSQC spectra at various pH values and subjected them to a PCA. The analysis revealed three apparent transitions with pK(a) values of 2.9, 4.9, and 6.8, consistent with previous reports using different methods. Next, Gdn-HCl-induced unfolding was examined by measuring tryptophan fluorescence at various pH values. Between pH 2 and 8, beta-lactoglobulin exhibited a number of structural transitions as well as changes in stability represented by the free energy change of unfolding, DeltaG(U). By combining the NMR and fluorescence results, the change in DeltaG(U) was suggested to result from the decreased pK(a) of some acidic residues. Notably, the native state at neutral pH is destabilized by deprotonation of Glu-89, leading to an increase in the relative population of the intermediate. Thus, the PCA of pH-dependent HSQC spectra provides a more comprehensive understanding of the stability and function of proteins.
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Affiliation(s)
- Kazumasa Sakurai
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Yuji Goto
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
- *To whom correspondence should be addressed: E-mail:
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32
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HOWELL NAZLINK, YEBOAH NANAA, LEWIS DAVIDF. Studies on the electrostatic interactions of lysozyme with α-lactalbumin and β-lactoglobulin. Int J Food Sci Technol 2007. [DOI: 10.1111/j.1365-2621.1995.tb01429.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Tosi E, Canna L, Lucero H, Ré E. Foaming properties of sweet whey solutions as modified by thermal treatment. Food Chem 2007. [DOI: 10.1016/j.foodchem.2005.11.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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34
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Purcell JM, Pessen H. Proton Longitudinal Relaxation Rates of Water in Aqueous Orthophosphoric Acid. ANAL LETT 2006. [DOI: 10.1080/00032718608064536] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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35
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Unterhaslberger G, Schmitt C, Sanchez C, Appolonia-Nouzille C, Raemy A. Heat denaturation and aggregation of β-lactoglobulin enriched WPI in the presence of arginine HCl, NaCl and guanidinium HCl at pH 4.0 and 7.0. Food Hydrocoll 2006. [DOI: 10.1016/j.foodhyd.2005.10.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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36
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Gelation of whey protein concentrate in the presence of partially hydrolyzed waxy maize starch and urea at pH 7.5. Colloid Polym Sci 2006. [DOI: 10.1007/s00396-006-1551-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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37
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Schmitt C, da Silva TP, Bovay C, Rami-Shojaei S, Frossard P, Kolodziejczyk E, Leser ME. Effect of time on the interfacial and foaming properties of beta-lactoglobulin/acacia gum electrostatic complexes and coacervates at pH 4.2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:7786-95. [PMID: 16089384 DOI: 10.1021/la0510984] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
The electrostatic complexation between beta-lactoglobulin and acacia gum was investigated at pH 4.2 and 25 degrees C. The binding isotherm revealed a spontaneous exothermic reaction, leading to a DeltaHobs = -2108 kJ mol(-1) and a saturation protein to polysaccharide weight mixing ratio of 2:1. Soluble electrostatic complexes formed in these conditions were characterized by a hydrodynamic diameter of 119 +/- 0.6 nm and a polydispersity index of 0.097. The effect of time on the interfacial and foaming properties of these soluble complexes was investigated at a concentration of 0.1 wt % at two different times after mixing (4 min, referred as t approximately 0 h and t = 24 h). At t approximately 0 h, the mixture is mainly made of aggregating soluble electrostatic complexes, whereas after 24 h these complexes have already insolubilize to form liquid coacervates. The surface elasticity, viscosity and phase angle obtained at low frequency (0.01 Hz) using oscillating bubble tensiometry revealed higher fluidity and less rigidity in the film formed at t approximately 0 h. This observation was confirmed by diminishing bubble experiments coupled with microscopy of the thin film. It was thicker, more homogeneous and contained more water at t approximately 0 h as compared to t = 24 h (thinner film, less water). This led to very different gas permeability's of Kt approximately 0 h = 0.021 cm s(-1) and Kt=24 h) = 0.449 cm s(-1), respectively. Aqueous foams produced with the beta-lactoglobulin/acacia gum electrostatic complexes or coacervates exhibited very different stability. The former (t approximately 0 h) had a stable volume, combining low drainage rate and mainly air bubble disproportionation as the destabilization mechanism. By contrast, using coacervates aged for 24 h, the foam was significantly less stable, combining fast liquid drainage and air bubble destabilization though fast gas diffusion followed by film rupture and bubble coalescence. The strong effect of time on the air/water interfacial properties of the beta-lactoglobulin/acacia gum electrostatic complexes can be understood by their reorganization at the interface to form a coacervate phase that is more fluid/viscous at t approximately 0 h vs rigid/elastic at t = 24 h.
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Affiliation(s)
- Christophe Schmitt
- Department of Food Science, Nestlé Research Center, Vers-chez-les-Blanc, CH-1000 Lausanne 26, Switzerland.
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38
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Gottschalk M, Nilsson H, Roos H, Halle B. Protein self-association in solution: the bovine beta -lactoglobulin dimer and octamer. Protein Sci 2004; 12:2404-11. [PMID: 14573854 PMCID: PMC2366967 DOI: 10.1110/ps.0305903] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
We have used proton magnetic relaxation dispersion (MRD) to study the self-association of bovine beta-lactoglobulin variant A (BLG-A) as a function of temperature at pH 4.7 (dimer-octamer equilibrium) and as a function of NaCl concentration at pH 2.5 (monomer-dimer equilibrium). The MRD method identifies coexisting oligomers from their rotational correlation times and determines their relative populations from the associated dispersion amplitudes. From MRD-derived correlation times and hydrodynamic model calculations, we confirm that BLG-A dimers associate to octamers below room temperature. The tendency for BLG-A dimers to assemble into octamers is found to be considerably weaker than in previous light scattering studies in the presence of buffer salt. At pH 2.5, the MRD data are consistent with an essentially complete transition from monomers in the absence of salt to dimers in 1 M NaCl. Because of an interfering relaxation dispersion from nanosecond water exchange, we cannot determine the oligomer populations at intermediate salt concentrations. This nanosecond dispersion may reflect intersite exchange of water molecules trapped inside the large binding cavity of BLG-A.
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Affiliation(s)
- Michael Gottschalk
- Department of Biophysical Chemistry, Lund University, SE-22100 Lund, Sweden
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39
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Girard M, Sanchez C, Laneuville SI, Turgeon SL, Gauthier SF. Associative phase separation of β-lactoglobulin/pectin solutions: a kinetic study by small angle static light scattering. Colloids Surf B Biointerfaces 2004; 35:15-22. [PMID: 15261050 DOI: 10.1016/j.colsurfb.2004.02.002] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/05/2004] [Indexed: 11/15/2022]
Abstract
Interpolymer complexation between beta-lactoglobulin (beta-lg) and pectin led to phase separation. Small angle static light scattering and phase contrast microscopy were used to monitor the phase separation of beta-lg/low-methoxyl or high-methoxyl-pectin (LM- or HM-pectin) dispersions as they were slowly acidified from pH 7 to 4 with glucono-delta-lactone (GDL). The monotonic decrease in scattered light intensity with the wave vector was associated with a nucleation and growth phase separation mechanism. Microscopic observations and turbidity measurements showed the increase of complex amounts with lower pH and at higher beta-lg/pectin ratios. The formation of intrapolymer complexes was initiated at pH 6.4 with the LM-pectin and at pH 5.0 with the HM-pectin. Local ordering with increasing amounts of small complexes was observed as scattered light intensity increased at intermediate q values. The beta-lg/LM-pectin complexes at the 5:1 and the 2:1 weight ratios and the beta-lg/HM-pectin complexes at 5:1 weight ratio have fractal structures. The formation of large amounts of small assemblies and sedimentation would be responsible for the decrease in the number and volume mean diameters and fractal dimension of beta-lg/LM-pectin complexes over time.
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Affiliation(s)
- Maude Girard
- Faculté des sciences de l'agriculture et de l'alimentation, Centre de recherche en sciences et technologie du lait STELA, Université Laval, Qué., Qc, Canada G1K 7P4
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40
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Bazinet L, Ippersiel D, Mahdavi B. Effect of conductivity control on the separation of whey proteins by bipolar membrane electroacidification. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2004; 52:1980-1984. [PMID: 15053539 DOI: 10.1021/jf0348469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Since the limiting factor of the bipolar membrane electroacidification (BMEA) process at 20% WPI (whey protein isolate) was hypothesized to be the lack of mobile ion inherent to the protein solution at pH 5.0, the aim of the present work is to study the effect of the conductivity control on the precipitation behavior of whey protein. BMEA performances were evaluated by measuring electrodialytic parameters, protein kinetic precipitation, molecular profiles, and isolate chemical composition and purity. The highest protein precipitation with 10% WPI solution was obtained at pH 4.6 and at a conductivity level of 200 microS/cm maintained with many 0.4-mL additions of 1.0 M KCl (200 microS[+]), with a 46% precipitation of the total protein, beta-lg composing the main part of the precipitated protein. With a 20% WPI solution, it was possible to reach pH 4.65 with conductivity control at 350 microS/cm. However, the 27% protein precipitation was still low. The changes in viscosity as pH decreases observed at 20% WPI would decreased the final precipitation rate of beta-lg, since the viscosity of the 20% WPI dispersion was very different.
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Affiliation(s)
- Laurent Bazinet
- Agriculture and Agri-Food Canada, Food Research and Development Centre, 3600 Casavant Boulevard West, St. Hyacinthe, Québec J2S 8E3, Canada.
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41
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Gun'ko VM, Klyueva AV, Levchuk YN, Leboda R. Photon correlation spectroscopy investigations of proteins. Adv Colloid Interface Sci 2003; 105:201-328. [PMID: 12969646 DOI: 10.1016/s0001-8686(03)00091-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Physical principles of photon correlation spectroscopy (PCS), mathematical treatment of the PCS data (converting autocorrelation functions to distribution functions or average characteristics), and PCS applications to study proteins and other biomacromolecules in aqueous media are described and analysed. The PCS investigations of conformational changes in protein molecules, their aggregation itself or in consequence of interaction with other molecules or organic (polymers) and inorganic (e.g. fumed silica) fine particles as well as the influence of low molecular compounds (surfactants, drugs, salts, metal ions, etc.) reveal unique capability of the PCS techniques for elucidation of important native functions of proteins and other biomacromolecules (DNA, RNA, etc.) or microorganisms (Escherichia coli, Pseudomonas putida, Dunaliella viridis, etc.). Special attention is paid to the interaction of proteins with fumed oxides and the impact of polymers and fine oxide particles on the motion of living flagellar microorganisms analysed by means of PCS.
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Affiliation(s)
- Vladimir M Gun'ko
- Institute of Surface Chemistry, 17 General Naumov Street, Kiev 03164, Ukraine.
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42
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Girard M, Turgeon SL, Gauthier SF. Thermodynamic parameters of beta-lactoglobulin-pectin complexes assessed by isothermal titration calorimetry. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2003; 51:4450-4455. [PMID: 12848524 DOI: 10.1021/jf0259359] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Isothermal titration calorimetry (ITC) was used to determine the binding constant, stoichiometry, enthalpy, and entropy of beta-lactoglobulin/low- and high-methoxyl pectin (beta-lg-LM- and HM-pectin) complexes at 22 degrees C and at pH 4. The binding isotherms revealed the formation of soluble intrapolymer complexes (C1) further followed by their aggregation in interpolymer complexes (C2). The interaction between beta-lg and LM- or HM-pectin in C1 and C2 occurred spontaneously with a Gibbs free energy around -10 kcal/mol. The C1 were enthalpically driven, whereas enthalpic and entropic factors were involved in the C2 formation. Because ITC did not allow the dissociation of different enthalpic contributions, the values measured as pectin and beta-lg interacted could partially be attributed to conformational changes. The C1 had a binding stoichiometry of 8.3 and 6.1 beta-lg molecules complexed per LM- or HM-pectin molecule, respectively. The C2 had about 16.5 and 15.1 beta-lg molecules complexed per LM- and HM-pectin, respectively.
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Affiliation(s)
- Maude Girard
- STELA Dairy Research Centre, Faculté des sciences de l'agriculture et de l'alimentation, Pavillon Paul-Comtois, Université Laval, Québec, Canada, G1K 7P4
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43
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44
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Noiseux I, Gauthier SF, Turgeon SL. Interactions between bovine beta-lactoglobulin and peptides under different physicochemical conditions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2002; 50:1587-1592. [PMID: 11879041 DOI: 10.1021/jf010887y] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The aim of this study was to determine if peptides could interact with beta-lactoglobulin (beta-LG) and what the physicochemical conditions promoting their interaction with the protein are. The binding of negatively charged (beta-LG 125-135 and 130-135), positively charged (beta-LG 69-83 and 146-149), and hydrophobic (alphaS1-CN 23-34 and beta-LG 102-105, both bioactive peptides) peptides to bovine beta-LG was determined using an ultrafiltration method under different physicochemical conditions: pH 3.0, 6.8, and 8.0; buffers of 0.05 and 0.1 M; 4, 25, and 40 degrees C; beta-LG/peptide ratios of 1:5 and 1:10. At pH 3.0, none of the peptides interacted with beta-LG at any temperature, buffer molarity, or beta-LG/peptide ratio probably due to electrostatic repulsions between the highly protonated species. At pH 6.8 and 8.0, charged peptides beta-LG 130-135, 69-83, and 146-149 bound to beta-LG under some physicochemical conditions, possibly by nonspecific binding. However, both hydrophobic peptides probably bind to the inner cavity (beta-barrel) of beta-LG, provoking the release of materials absorbing at 214 nm. Given the known biological activities of the hydrophobic peptides used in this study (opioid and ACE-inhibitory activities), their binding to beta-LG may be relevant to a better understanding of the physiological function of the protein.
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Affiliation(s)
- Isabelle Noiseux
- Centre de Recherche STELA, Département de Sciences des Aliments et de Nutrition, Pavillon Paul-Comtois, Université Laval, Québec, Québec, Canada G1K7P4
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45
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Taulier N, Chalikian TV. Characterization of pH-induced transitions of beta-lactoglobulin: ultrasonic, densimetric, and spectroscopic studies. J Mol Biol 2001; 314:873-89. [PMID: 11734004 DOI: 10.1006/jmbi.2001.5188] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Depending on solution conditions, beta-lactoglobulin can exist in one of its six pH-dependent structural states. We have characterized the acid and basic-induced conformational transitions between these structural states over the pH range of pH 1 to pH 13. To this end, we have employed high-precision ultrasonic and densimetric measurements coupled with fluorescence and CD spectroscopic data. Our combined spectroscopic and volumetric results have revealed five pH-induced transitions of beta-lactoglobulin between pH 1 and pH 13. The first transition starts at pH 2 and is not completed even at pH 1, our lowest experimental pH. This transition is followed by the dimer-to-monomer transition of beta-lactoglobulin between pH 2.5 and pH 4. The dimer-to-monomer transition is accompanied by decreases in volume, v degrees (-0.008(+/-0.003) cm3 x g(-1)), and adiabatic compressibility, k degrees (S) (-(0.7(+/-0.4))x10(-6) cm3 x g(-1) x bar(-1)). We interpret the observed changes in volume and compressibility associated with the dimer-to-monomer transition of beta-lactoglobulin, in conjunction with X-ray crystallographic data, as suggesting a 7 % increase in protein hydration, with the hydration changes being localized in the area of contact between the two monomeric subunits. The so-called N-to-Q transition of beta-lactoglobulin occurs between pH 4.5 and pH 6 and is accompanied by increases in volume, v degrees (0.004(+/-0.003) cm3 x g(-1)), and compressibility, k degrees (S) ((0.7(+/-0.4))x10(-6) cm3 x g(-1) x bar(-1)). The Tanford transition of beta-lactoglobulin is centered at pH 7.5 and is accompanied by a decrease in volume, v degrees (-0.006(+/-0.003) cm3 x g(-1)), and an increase in compressibility, k degrees (S) ((1.5(+/-0.5))x10(-6) cm3 x g(-1) x bar(-1)). Based on these volumetric results, we propose that the Tanford transition is accompanied by a 5 to 10 % increase in the protein hydration and a loosening of the interior packing of beta-lactoglobulin as reflected in a 12 % increase in its intrinsic compressibility. Finally, above pH 9, the protein undergoes irreversible base-induced unfolding which is accompanied by decreases in v degrees (-0.014(+/-0.003) cm3 x g(-1)) and k degrees (S) (-(7.0(+/-0.5))x10(-6) cm3 x g(-1) x bar(-1)). Combining these results with our CD spectroscopic data, we propose that, in the base-induced unfolded state of beta-lactoglobulin, only 80 % of the surface area of the fully unfolded conformation is exposed to the solvent. Thus, in so far as solvent exposure is concerned, the base-induced unfolded states of beta-lactoglobulin retains some order, with 20 % of its amino acid residues remaining solvent inaccessible.
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Affiliation(s)
- N Taulier
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto, 19 Russell Street, Toronto, Ontario, M5S 2S2, Canada
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46
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Lefèvre T, Subirade M. Conformational rearrangement of beta-lactoglobulin upon interaction with an anionic membrane. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1549:37-50. [PMID: 11566367 DOI: 10.1016/s0167-4838(01)00242-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Interactions between beta-lactoglobulin (beta-lg) and dimyristoylphosphatidylglycerol (DMPG) bilayers were studied using one- and two-dimensional infrared spectroscopy above (pD 7.4) and below (pD 4.4) the protein's (beta-lg's) isoelectric point (pI=5.2). The aim of the study was threefold: (1) gain a better understanding of beta-lg-phospholipid interaction; (2) provide information relative to the structure of beta-lg as it interacts with membranes; (3) determine whether the conformational modifications of the protein in the presence of lipids are strictly caused by thermal effects or whether they are modulated by the chain-melting phase transition. At pD 7.4, the lipid thermotropism, the acyl-chain order, and the membrane interfacial region were essentially unaffected by the presence of beta-lg, whereas the protein amide I region showed dramatic alterations. The results suggested the predominance of beta-sheets and alpha-helix elements, with a lost of structural integrity. At pD 4.4, beta-lg induced an approximately 2 degrees C downshift of the transition temperature, whereas the conformational order of the lipid chain decreased in the gel phase and increased in the liquid-crystalline phase. The hydration state of the DMPG C==O groups increased in the liquid-crystalline phase. The conformation of beta-lg at pD 4.4 in the presence of DMPG showed similarities with that observed at pD 7.4, but an increase in the alpha-helix content and a reduced thermal stability were noticed. In contrast to the protein alone, beta-lg aggregates in the presence of DMPG at pD 4.4 above 50 degrees C. At both pD values, the charged surface of the membrane seemed to be the main factor for inducing protein conformational changes by altering the intramolecular interactions that stabilize the native structure. However, protein incorporation within the membrane seemed to be involved at pD 4.4. The two-dimensional analysis performed with spectra recorded upon heating showed that spectral intensity changes at pD 4.4 and 7.4 occurred at the same frequencies in the amide I' region. The heat-induced structural changes of beta-lg were not correlated with the conformational modifications of the phospholipids along the phase transition, indicating that the thermal behavior of the protein was not modulated by the lipid chain melting, but rather represented the heat-induced protein rearrangement in the presence of DMPG.
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Affiliation(s)
- T Lefèvre
- Centre de Recherches en Sciences et Technologie du Lait (STELA), Département d'Alimentation et de Nutrition, Faculté des Sciences de l'Agriculture et de l'Alimentation, Pavillon Paul Comtois, Université Laval, Sainte-Foy, QC, Canada G1K 7P4
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47
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Nicolai T, Urban C, Schurtenberger P. Light Scattering Study of Turbid Heat-Set Globular Protein Gels Using Cross-Correlation Dynamic Light Scattering. J Colloid Interface Sci 2001; 240:419-424. [PMID: 11482949 DOI: 10.1006/jcis.2001.7672] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structure factor of aqueous solutions of the globular protein beta-lactoglobulin was determined as a function of heating time at 76 degrees C. We show how the effect of multiple scattering on the scattered light intensity can be effectively corrected using cross-correlation dynamic light scattering even if the transmission is only 1%. The structure factor of aggregated and gelled proteins can be described by the Ornstein-Zernike equation. The system is characterized by a correlation length that increases with heating time and stabilizes some time after the gel is formed. The correlation length of the protein gels decreases with decreasing concentration. Measurements after progressive dilution of a sample close to the gel point showed that the protein aggregates are initially interpenetrated and disinterpenetrate upon dilution. Copyright 2001 Academic Press.
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Affiliation(s)
- Taco Nicolai
- Polyméres, Colloides, Interfaces, UMR-CNRS, Université du Maine, Le Mans Cedex 9, 72085, France
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48
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Palazolo G, Rodríguez F, Farruggia B, Picó G, Delorenzi N. Heat treatment of beta-lactoglobulin: structural changes studied by partitioning and fluorescence. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2000; 48:3817-3822. [PMID: 10995276 DOI: 10.1021/jf991353o] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Functional properties of whey protein concentrates (WPC) are primarily dependent on the degree of denaturation of beta-lactoglobulin (beta-LG), the major globular whey protein. Irreversible modifications in the tertiary structure and association state of beta-LG after heat treatment were studied by partition in aqueous two-phase systems and fluorescence quenching. Partitioning of preheated beta-LG in two-phase systems containing 5% (w/w) poly(ethylene glycol) and 7% (w/w) dextran, between pH 6.0 and7.0, are appropriately related with the intensity of heat treatment. An increase in the partition coefficient of beta-LG was observed with increasing temperature of heat treatment. On the other hand, fluorescence quenching of beta-LG by acrylamide was used to study the conformational flexibility of the protein at pH values between 4. 0 and 9.0. The values of bimolecular quenching rate constant (k(q)) obtained showed that beta-LG appears to be more flexible at high pH values, while at low pH the protein assumes a more compact form. The efficiency of acrylamide quenching on preheated beta-LG was substantially more pronounced than for the untreated protein. This difference can be ascribed to the presence of unfolded monomers and aggregates of denatured molecules formed after heat treatment, whose tryptophanyl residues are more exposed to the solvent. In conclusion, the results suggest that partition studies in aqueous two-phase systems and fluorescence quenching are very useful tools to detect changes in conformation and aggregation of beta-LG induced by heat treatment.
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Affiliation(s)
- G Palazolo
- Area Fisicoquímica, Departamento de Química-Física, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Suipacha 531 (2000), Rosario, Argentina
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49
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Takata SI, Norisuye T, Tanaka N, Shibayama M. Heat-Induced Gelation of β-Lactoglobulin. 1. Time-Resolved Dynamic Light Scattering. Macromolecules 2000. [DOI: 10.1021/ma0003295] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shin-ich Takata
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Tomohisa Norisuye
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Naoki Tanaka
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Mitsuhiro Shibayama
- Department of Polymer Science and Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
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50
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Barteri M, Gaudiano MC, Rotella S, Benagiano G, Pala A. Effect of pH on the structure and aggregation of human glycodelin A. A comparison with beta-lactoglobulin A. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1479:255-64. [PMID: 11004543 DOI: 10.1016/s0167-4838(00)00021-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The effect of pH on the structure of glycodelin A (GdA) and of beta-lactoglobulin A (beta-LgA) has been investigated by means of circular dichroism, steady state fluorescence, synchrotron radiation small angle X-ray scattering (SR-SAXS) and gel permeation chromatography. The comparison between GdA and beta-LgA shows that, at pH 7.0, both proteins are dimers with an extended content of beta-sheet conformation, but pH 2.0 and 9.0 yield a different secondary, tertiary and quaternary structural organisation. Whilst beta-LgA is a monomer, that conserves beta-sheet conformation at pH 2.0 and 9.0, GdA has a stable dimeric structure at alkaline pH, but at pH 2.0 increases its alpha-helix content and it aggregates soon. SR beam has been used to perform SAXS comparative measurements of the two proteins. SR-SAXS data provide the radius of gyration and the radii of the cross-section and of the thickness. GdA aggregation at acid pH has been characterised by calculating the distance distribution function (P(r)). Isoelectric focusing and chromatofocusing data show a different charge distribution on the surfaces of the two proteins, supporting the hypothesis that the presence of oligosaccharides deeply influences the conformational state and the aggregation process of GdA at different pH values. In particular, the presence of sialic acid residues, within the oligosaccharide moiety of the GdA, might be responsible for the differences observed between the two proteins.
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Affiliation(s)
- M Barteri
- Dipartimento di Chimica, Università degli Studi La Sapienza, Rome, Italy.
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