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Melnikova D, Ranjan VV, Nesmelov YE, Skirda VD, Nesmelova IV. Translational Diffusion and Self-Association of an Intrinsically Disordered Protein κ-Casein Using NMR with Ultra-High Pulsed-Field Gradient and Time-Resolved FRET. J Phys Chem B 2024; 128:7781-7791. [PMID: 39106061 PMCID: PMC11331516 DOI: 10.1021/acs.jpcb.4c03625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Revised: 07/09/2024] [Accepted: 07/17/2024] [Indexed: 08/07/2024]
Abstract
Much attention has been given to studying the translational diffusion of globular proteins, whereas the translational diffusion of intrinsically disordered proteins (IDPs) is less studied. In this study, we investigate the translational diffusion and how it is affected by the self-association of an IDP, κ-casein, using pulsed-field gradient nuclear magnetic resonance and time-resolved Förster resonance energy transfer. Using the analysis of the shape of diffusion attenuation and the concentration dependence of κ-casein diffusion coefficients and intermolecular interactions, we demonstrate that κ-casein exhibits continuous self-association. When the volume fraction of κ-casein is below 0.08, we observe that κ-casein self-association results in a macroscopic phase separation upon storage at 4 °C. At κ-casein volume fractions above 0.08, self-association leads to the formation of labile gel-like networks without subsequent macroscopic phase separation. Unlike α-casein, which shows a strong concentration dependence and extensive gel-like network formation, only one-third of κ-casein molecules participate in the gel network at a time, resulting in a more dynamic and less extensive structure. These findings highlight the unique association properties of κ-casein, contributing to a better understanding of its behavior under various conditions and its potential role in casein micelle formation.
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Affiliation(s)
- Daria
L. Melnikova
- Department
of Physics of Molecular Systems, Kazan Federal
University, Kazan 420011, Russia
| | - Venkatesh V. Ranjan
- Department
of Chemistry, University of North Carolina, Charlotte, North Carolina 28223, United States
- Department
of Physics and Optical Sciences, University
of North Carolina, Charlotte, North Carolina 28223, United States
| | - Yuri E. Nesmelov
- Department
of Physics and Optical Sciences, University
of North Carolina, Charlotte, North Carolina 28223, United States
| | - Vladimir D. Skirda
- Department
of Physics of Molecular Systems, Kazan Federal
University, Kazan 420011, Russia
| | - Irina V. Nesmelova
- Department
of Physics and Optical Sciences, University
of North Carolina, Charlotte, North Carolina 28223, United States
- School
of Data Science, University of North Carolina, Charlotte, North Carolina 28223, United States
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2
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Thesbjerg MN, Sundekilde UK, Poulsen NA, Larsen LB, Nielsen SDH. A novel proteomic approach for the identification and relative quantification of disulfide-bridges in the human milk proteome. J Proteomics 2024; 301:105194. [PMID: 38723850 DOI: 10.1016/j.jprot.2024.105194] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Revised: 04/26/2024] [Accepted: 05/05/2024] [Indexed: 05/13/2024]
Abstract
This study explores the disulfide bridges present in the human milk proteome by a novel approach permitting both positional identification and relative quantification of the disulfide bridges. Human milk from six donors was subjected to trypsin digestion without reduction. The digested human milk proteins were analyzed by nanoLC-timsTOF Pro combined with data analysis using xiSEARCH. A total of 85 unique disulfide bridges were identified in 25 different human milk proteins. The total relative abundance of disulfide bridge-containing peptides constituted approximately 5% of the total amount of tryptic-peptides. Seven inter-molecular disulfide bridges were identified between either α-lactalbumin and lactotransferrin (5) or αS1-casein and κ-casein (2). All cysteines involved in the observed disulfide bridges of α-lactalbumin and lactotransferrin were mapped onto protein models using AlphaFold2 Multimer to estimate the length of the observed disulfide bridges. The lengths of the disulfide bridges of lactotransferrin indicate a potential for multi- or poly-merization of lactotransferrin. The high number of intramolecular lactotransferrin disulfide bridges identified, suggests that these are more heterogeneous than previously presumed. SIGNIFICANCE: Disulfide-bridges in the human milk proteome are an often overseen post-transaltional modification. Thus, mapping the disulfide-bridges, their positions and relative abundance, are valuable new knowledge needed for an improved understanding of human milk protein behaviour. Although glycosylation and phosphorylation have been described, even less information is available on the disulfide bridges and the disulfide-bridge derived protein complexes. This is important for future work in precision fermentation for recombinant production of human milk proteins, as this will highlight which disulfide-bridges are naturally occouring in human milk proteins. Further, this knowledge would be of value for the infant formula industry as it provides more information on how to humanize bovine-milk based infant formula. The novel method developed here can be broadly applied in other biological systems as the disulfid-brigdes are important for the structure and functionality of proteins.
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Affiliation(s)
- Martin Nørmark Thesbjerg
- Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark; Sino-Danish College (SDC), University of Chinese Academy of Science, Huairou District, Beijing 101408, China.
| | | | - Nina Aagaard Poulsen
- Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark
| | - Lotte Bach Larsen
- Department of Food Science, Aarhus University, Agro Food Park 48, DK-8200 Aarhus N, Denmark
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3
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Rangel AHDN, Bezerra DAFVDA, Sales DC, Araújo EDOM, Lucena LMD, Porto ALF, Véras ÍVUM, Lacerda AF, Ribeiro CVDM, Anaya K. An Overview of the Occurrence of Bioactive Peptides in Different Types of Cheeses. Foods 2023; 12:4261. [PMID: 38231707 DOI: 10.3390/foods12234261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/25/2023] [Accepted: 10/05/2023] [Indexed: 01/19/2024] Open
Abstract
The search for improvements in quality of life has increasingly involved changes in the diet, especially the consumption of foods which, in addition to having good nutritional value, are characterized by offering health benefits. Among the molecules that trigger several beneficial responses are peptides, which are specific fragments of proteins known to produce positive effects on the human body. This review aimed to discuss the bioactive potential of peptides from cheeses. Studies show that the protein composition of some cheese varieties exhibits a potential for the release of bioactive peptides. The production of these peptides can be promoted by some technological procedures that affect the milk structure and constituents. The cheese maturation process stands out for producing bioactive peptides due to the action of enzymes produced by lactic acid bacteria. Thus, in addition to being proteins with high biological value due to their excellent amino acid profile, peptides from some types of cheeses are endowed with functional properties such as anti-hypertensive, antimicrobial, antioxidant, anticarcinogenic, opioid, and zinc-binding activities.
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Affiliation(s)
| | | | - Danielle Cavalcanti Sales
- Academic Unit Specialized in Agricultural, Federal University of Rio Grande do Norte (UFRN), Macaiba 59280000, Brazil
| | | | - Luis Medeiros de Lucena
- Academic Unit Specialized in Agricultural, Federal University of Rio Grande do Norte (UFRN), Macaiba 59280000, Brazil
| | - Ana Lúcia Figueiredo Porto
- Morfology and Animal Fisiology Departament, Rural Federal University of Pernambuco (UFRPE), Recife 55292901, Brazil
| | | | - Ariane Ferreira Lacerda
- Federal Institute of Education, Science and Technology (IFRN), Currais Novos 59380000, Brazil
| | | | - Katya Anaya
- Faculty of Health Sciences of Trairi, Federal University of Rio Grande do Norte (UFRN), Santa Cruz 59200000, Brazil
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Moatsou G. Heat treatment of goat milk – A review. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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5
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Targeted Bottom-Up Mass Spectrometry Approach for the Relative Quantification of Post-Translational Modification of Bovine κ-Casein during Milk Fermentation. Molecules 2022; 27:molecules27185834. [PMID: 36144569 PMCID: PMC9506521 DOI: 10.3390/molecules27185834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/02/2022] [Accepted: 09/05/2022] [Indexed: 11/16/2022] Open
Abstract
κ-casein (κ-CN) is one of the key components in bovine milk, playing a unique role in the structuration of casein micelles. It contains in its chemical structure up to sixteen amino acid residues (mainly serine and threonine) susceptible to modifications, including glycosylation and phosphorylation, which may further be formed during milk processing. In this study, changes in post-translational modification (PTM) of κ-CN during bovine milk fermentation were investigated. One-to-five-day fermented milk samples were produced. A traditional bottom−up proteomics approach was used to establish a multiple-reaction monitoring (MRM) method for relative quantification of κ-CN PTM. Endoproteinase Glu-C was found to efficiently digest the κ-CN molecule. The developed LC-MS method was validated by performing assessments of linearity, precision, repeatability, reproducibility, limit of detection (LOD), and limit of quantification (LOQ). Among the yielded peptides, four of them containing serine and threonine residues were identified and the unmodified as well as the modified variants of each of them were relatively quantified. These peptides were (1) IPTINTIASGEPTSTTE [140, 158], (2) STVATLE [162, 168], (3) DSPE [169, 172], and (4) INTVQVTSTAV [180, 190]. Distribution analysis between unmodified and modified peptides revealed that over 50% of κ-CN was found in one of its modified forms in milk. The fermentation process further significantly altered the composition between unmodified/modified κ-CN, with glycoslaytion being predominant compared to phosphorylation (p < 0.01). Further method development towards α and β-CN fractions and their PTM behavior would be an asset to better understand the changes undergone by milk proteins and the micellar structure during fermentation.
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Anema SG. Heat-induced changes in caseins and casein micelles, including interactions with denatured whey proteins. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105136] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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8
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Meng F, Uniacke-Lowe T, Ryan AC, Kelly AL. The composition and physico-chemical properties of human milk: A review. Trends Food Sci Technol 2021. [DOI: 10.1016/j.tifs.2021.03.040] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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9
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Sequence characteristics responsible for protein‐protein interactions in the intrinsically disordered regions of caseins, amelogenins, and small heat‐shock proteins. Biopolymers 2019; 110:e23319. [DOI: 10.1002/bip.23319] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2019] [Revised: 06/11/2019] [Accepted: 06/19/2019] [Indexed: 01/01/2023]
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10
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Krüger CCH, Azevedo TD, Piltz MT, Silva ÁT, Cândido LMB. Casein-derived peptides as an alternative ingredient for low-phenylalanine diets. NUTR HOSP 2019; 36:718-722. [PMID: 30958685 DOI: 10.20960/nh.2391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023] Open
Abstract
Introduction: casein-derived peptides can be liberated both in vivo via normal digestion of casein, as well as in vitro via enzymatic hydrolysis. These peptides were suggested to have biological activity. Objectives: the aim of this study was to describe the production and characterization of casein peptides and to explore the potential of these peptides as an option for low-phenylalanine diets. Methods: peptides were produced by tryptic hydrolysis of sodium caseinate and acid precipitation with HCl, followed by precipitation with ethanol or aggregation of CaCl2 or ZnSO4. Results: the amino acid analysis revealed a significant reduction in the amount of phenylalanine from the original protein. Conclusion: casein-derived peptides could be a future alternative of short chain peptides to low-phenylalanine formulations.
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Affiliation(s)
| | - Thaise D Azevedo
- Food and Nutrition Post Graduate Program. Federal University of Paraná
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11
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Carver JA, Holt C. Functional and dysfunctional folding, association and aggregation of caseins. PROTEIN MISFOLDING 2019; 118:163-216. [DOI: 10.1016/bs.apcsb.2019.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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12
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Silva M, Zisu B, Chandrapala J. Influence of low-frequency ultrasound on the physico-chemical and structural characteristics of milk systems with varying casein to whey protein ratios. ULTRASONICS SONOCHEMISTRY 2018; 49:268-276. [PMID: 30122466 DOI: 10.1016/j.ultsonch.2018.08.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/24/2018] [Accepted: 08/11/2018] [Indexed: 06/08/2023]
Abstract
Casein and whey proteins respond differently to ultrasound treatment depending on the individual protein fraction and the delivered energy density. The main aim of this study was to determine the sonication-induced physiochemical and structural changes of protein solutions with varying casein to whey protein ratios as a function of processing time at 20 kHz ultrasound. Four different casein:whey protein ratios (80:20, 60:40, 50:50, 40:60) were prepared. Upon sonication, there was a reduction in particle size of the 80:20 and 60:40 ratios, but the particle size of 50:50 and 40:60 increased. Milk protein solutions with higher portion of caseins produced more hydrophobically driven aggregates while whey protein-rich milk protein solutions produced more disulphide mediated aggregates during sonication. Primarily, β-lactoglobulin was involved in the hydrophobic aggregation process and β-lactoglobulin, bovine serum albumin and κ-casein participated in the disulphide aggregation process at all ratios.
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Affiliation(s)
- Mayumi Silva
- School of Science, RMIT University, Bundoora, VIC 3083, Australia
| | - Bogdan Zisu
- School of Science, RMIT University, Bundoora, VIC 3083, Australia
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Mediwaththe A, Chandrapala J, Vasiljevic T. Shear-induced behaviour of native milk proteins heated at temperatures above 80 °C. Int Dairy J 2018. [DOI: 10.1016/j.idairyj.2017.09.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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14
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In vitro gastrointestinal digestion of purified bovine kappa-casein variants A, B, and E: Effects on antioxidant and angiotensin 1-converting enzyme inhibitory capacity. Int Dairy J 2016. [DOI: 10.1016/j.idairyj.2016.02.036] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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16
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Investigating the chaperone activity of β-casein in preventing amyloid formation in κ-casein in the presence of dextran. JOURNAL OF PHARMACEUTICAL INVESTIGATION 2015. [DOI: 10.1007/s40005-015-0183-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Tu ZC, Zhang L, Wang H, Huang XQ, Zhang L, Yang K. Structure and Antioxidant Activity of Milk Model Systems after Microwave Heating. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2014. [DOI: 10.3136/fstr.20.345] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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18
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Holt C, Carver JA, Ecroyd H, Thorn DC. Invited review: Caseins and the casein micelle: their biological functions, structures, and behavior in foods. J Dairy Sci 2013; 96:6127-46. [PMID: 23958008 DOI: 10.3168/jds.2013-6831] [Citation(s) in RCA: 286] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 06/09/2013] [Indexed: 12/27/2022]
Abstract
A typical casein micelle contains thousands of casein molecules, most of which form thermodynamically stable complexes with nanoclusters of amorphous calcium phosphate. Like many other unfolded proteins, caseins have an actual or potential tendency to assemble into toxic amyloid fibrils, particularly at the high concentrations found in milk. Fibrils do not form in milk because an alternative aggregation pathway is followed that results in formation of the casein micelle. As a result of forming micelles, nutritious milk can be secreted and stored without causing either pathological calcification or amyloidosis of the mother's mammary tissue. The ability to sequester nanoclusters of amorphous calcium phosphate in a stable complex is not unique to caseins. It has been demonstrated using a number of noncasein secreted phosphoproteins and may be of general physiological importance in preventing calcification of other biofluids and soft tissues. Thus, competent noncasein phosphoproteins have similar patterns of phosphorylation and the same type of flexible, unfolded conformation as caseins. The ability to suppress amyloid fibril formation by forming an alternative amorphous aggregate is also not unique to caseins and underlies the action of molecular chaperones such as the small heat-shock proteins. The open structure of the protein matrix of casein micelles is fragile and easily perturbed by changes in its environment. Perturbations can cause the polypeptide chains to segregate into regions of greater and lesser density. As a result, the reliable determination of the native structure of casein micelles continues to be extremely challenging. The biological functions of caseins, such as their chaperone activity, are determined by their composition and flexible conformation and by how the casein polypeptide chains interact with each other. These same properties determine how caseins behave in the manufacture of many dairy products and how they can be used as functional ingredients in other foods.
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Affiliation(s)
- C Holt
- Institute of Molecular, Cell and Systems Biology, School of Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
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19
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Famelart MH, Le NHT, Croguennec T, Rousseau F. Are disulphide bonds formed during acid gelation of preheated milk? Int J Food Sci Technol 2013. [DOI: 10.1111/ijfs.12174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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20
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Binding Interactions Between α-glucans from Lactobacillus reuteri and Milk Proteins Characterised by Surface Plasmon Resonance. FOOD BIOPHYS 2012. [DOI: 10.1007/s11483-012-9260-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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21
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Abstract
Proteomic analysis of bovine, caprine, buffalo, equine and camel milk highlighted significant interspecies differences. Camel milk was found to be devoid of β-lactoglobulin, whereas β-lactoglobulin was the major whey protein in bovine, buffalo, caprine, and equine milk. Five different isoforms of κ-casein were found in camel milk, analogous to the micro-heterogeneity observed for bovine κ-casein. Several spots observed in 2D-electrophoretograms of milk of all species could tentatively be identified as polypeptides arising from the enzymatic hydrolysis of caseins. The understanding gained from the proteomic comparison of these milks may be of relevance both in terms of identifying sources of hypoallergenic alternatives to bovine milk and detection of adulteration of milk samples and products.
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Sotres J, Svensson O, Arnebrant T. Friction force spectroscopy of β- and κ-casein monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:981-992. [PMID: 21182238 DOI: 10.1021/la1043377] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Friction force spectroscopy (FFS) has been applied to study the tribological properties of β- and κ-casein layers on hydrophobic substrates in aqueous solutions. Nanometer-sized imaging tips were employed. This allowed exerting and determining the high pressures needed to remove the layers and registering the topographic evolution during this process. Both β- and κ-casein layers showed similar and not particularly high initial frictional responses (friction coefficient of ∼1 when measured with a silicon nitride tip). The pressures needed to remove the layers were of the same order of magnitude for both proteins, ∼10(8) Pa, but slightly higher for those composed of β-casein. The technique has also shown to be useful in studying the two-dimensional lateral diffusion of the proteins and the wear on the layers they form.
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Affiliation(s)
- Javier Sotres
- Biomedical Laboratory Science and Technology, Faculty of Health and Society, Malmoe University, 20506 Malmoe, Sweden.
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Kawasaki K, Lafont AG, Sire JY. The Evolution of Milk Casein Genes from Tooth Genes before the Origin of Mammals. Mol Biol Evol 2011; 28:2053-61. [DOI: 10.1093/molbev/msr020] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Thompson AK, Singh H, Dalgleish DG. Use of surface plasmon resonance (SPR) to study the dissociation and polysaccharide binding of casein micelles and caseins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:11962-11968. [PMID: 20964432 DOI: 10.1021/jf102580r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Tests were made to determine whether surface plasmon resonance (SPR) could be used as a technique to study the dissociation properties of bovine casein micelles or of sodium caseinate and the interactions between these protein particles and different polysaccharides. Surfaces of bound micelles or caseinate were made, and the changes in refractive index of these layers were used to define changes in the structures of the chemisorbed material. The technique appears to have some potential for studying details of the dissociation of casein micelles and of the binding of different polysaccharides to caseins.
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Affiliation(s)
- Abby K Thompson
- The Riddet Institute, Massey University, Palmerston North, New Zealand
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25
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Chevalier F, Kelly AL. Proteomic quantification of disulfide-linked polymers in raw and heated bovine milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:7437-7444. [PMID: 20504025 DOI: 10.1021/jf1010879] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Disulfide bond formation between milk protein molecules was quantified in raw and heated bovine milk using reducing and nonreducing two-dimensional electrophoresis. Analysis of protein profiles in raw milk indicated that 18% of alpha(S2)-casein, 25% of beta-lactoglobulin, and 46% of kappa-casein molecules were involved in disulfide-linked complexes (calculated through differences in spot volumes on two-dimensional electrophoretograms under reducing and nonreducing conditions), whereas levels of alpha(S1)- and beta-caseins were similar under both conditions. Following heat treatment at 90 degrees C for 30 min, spot volumes of serum albumin, beta-lactoglobulin, and kappa-casein decreased by 85%, 75%, and 75%, respectively, with the formation of several spots on nonreducing gels corresponding to polymers. Homopolymers and heteropolymers of kappa-casein and alpha(S2)-casein were identified by mass spectrometry in raw milk samples; polymers involving only alpha(S2)-casein or only kappa-casein accounted for 43% and 12% of the total polymers present, respectively. In addition, 45% of polymers in raw milk involved alpha(S2)-casein in association with other proteins as heteropolymers, indicating the key role of this protein in intermolecular disulfide bridging between proteins in raw milk. The intensity of monomeric kappa-casein spots decreased progressively with heating time at 90 degrees C, with greatest changes in spots with acidic isoelectric points. Interactions and association of milk proteins via disulfide bridges are discussed in relation to the proteins involved and their potential protective function against formation of fibril aggregates.
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Affiliation(s)
- François Chevalier
- School of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
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Hidalgo ME, Pires MS, Risso PH. A study on bovine kappa-casein aggregation after the enzymatic action of chymosin. Colloids Surf B Biointerfaces 2010; 76:556-63. [DOI: 10.1016/j.colsurfb.2009.12.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Revised: 12/07/2009] [Accepted: 12/20/2009] [Indexed: 11/16/2022]
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Chevalier F, Hirtz C, Sommerer N, Kelly AL. Use of reducing/nonreducing two-dimensional electrophoresis for the study of disulfide-mediated interactions between proteins in raw and heated bovine milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2009; 57:5948-5955. [PMID: 19526987 DOI: 10.1021/jf900518n] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The composition and interactions of proteins in bovine milk, and modifications resulting from milk storage and processing, are complex and incompletely understood. Analysis of the milk proteome can elucidate milk protein expression, structure, interaction, and modifications. Raw milk was analyzed by two-dimensional electrophoresis (isolelectric focusing followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis) under reducing and nonreducing, or combined, conditions, followed by mass spectrometry of separated protein spots; a small number of high-abundance proteins, that is, caseins (alpha(S1)-, alpha(S2)-, beta-, kappa-, and gamma-), beta-lactoglobulin, alpha-lactalbumin, and serum albumin, represented the vast majority of protein spots on the two-dimensional electrophoretograms of raw milk samples, but some cross-linked protein complexes (mainly homopolymers of kappa-casein and alpha(S2)-casein but also some heteropolymeric complexes) were resolved under native/unheated conditions. When skim milk was heated to 90 degrees C for up to 10 min, the level of native whey proteins decreased in parallel with an increase in disulfide-linked complexes, including very complex heteropolymers, for example, casein/whey protein polymers containing multiple species. The analysis strategy used in this study reveals numerous disulfide-mediated interactions and can be proposed to analyze reduction/oxidation of milk and dairy product proteins following processing treatments applied for processing and storage.
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Affiliation(s)
- François Chevalier
- Department of Food and Nutritional Sciences, University College Cork, Cork, Ireland.
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28
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Guyomarc'h F, Nono M, Nicolai T, Durand D. Heat-induced aggregation of whey proteins in the presence of κ-casein or sodium caseinate. Food Hydrocoll 2009. [DOI: 10.1016/j.foodhyd.2008.07.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Johansson A, Lugand D, Rolet-Répécaud O, Mollé D, Delage MM, Peltre G, Marchesseau S, Léonil J, Dupont D. Epitope characterization of a supramolecular protein assembly with a collection of monoclonal antibodies: the case of casein micelle. Mol Immunol 2008; 46:1058-66. [PMID: 18992943 DOI: 10.1016/j.molimm.2008.09.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Revised: 09/23/2008] [Accepted: 09/24/2008] [Indexed: 11/29/2022]
Abstract
In milk, kappa-, beta-, alphas(1)- and alphas(2)-casein (CN) are associated into a supramolecular assembly, the micelle. In this work, CN micelles contained in fresh skim milk were used to produce over 100 monoclonal antibodies. The specificity of these probes was determined using libraries of synthetic peptides and peptides fractionated from tryptic hydrolysis of purified CNs. Although kappa-CN and alphas(2)-CN are minor proteins in the micelle (ratio 1:1:4:4 for kappa, alphas(2), alphas(1), beta) a proportionally high number of clones were produced towards these two proteins (32 for each), compared to 9 and 29 for alphas(1)-CN and beta-CN, respectively. Most of the beta-CN and kappa-CN epitopes were identified, while about 50% of alphas(1)-CN and alphas(2)-CN antibodies were suspected to react to conformational linear or discontinuous epitopes, since no peptide binding could be identified. Antibody binding to the phosphoserine rich regions of the three calcium sensitive CNs was weak or non-existing, suggesting them to be hidden in the micelle structure together with alphas(1)-CN. The C-terminal glycomacropeptide of kappa-CN and the C-terminal moiety of beta-CN were well exposed generating the majority of the antibodies specific for these two proteins. The two major antigenic sites of alphas(2) were alphas(2)-CN (f96-114) and (f16-35). Cross-reaction between alphas(2)-CN specific antibodies with alphas(1)-CN illustrated the tangled structure between the two proteins. Immuno-dominant epitopes identified in the present study totally differ from those known for the purified caseins suggesting they were specific for the micelle supramolecular structure.
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Affiliation(s)
- Annette Johansson
- INRA-Unité de Recherches en Technologie et Analyses Latières, BP 20089, F-39800 Poligny, France
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Holland JW, Deeth HC, Alewood PF. Analysis of disulphide linkages in bovine κ-casein oligomers using two-dimensional electrophoresis. Electrophoresis 2008; 29:2402-10. [DOI: 10.1002/elps.200700840] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bönisch MP, Lauber S, Kulozik U. Improvement of enzymatic cross-linking of casein micelles with transglutaminase by glutathione addition. Int Dairy J 2007. [DOI: 10.1016/j.idairyj.2006.01.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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33
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Patel HA, Singh H, Anema SG, Creamer LK. Effects of heat and high hydrostatic pressure treatments on disulfide bonding interchanges among the proteins in skim milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:3409-20. [PMID: 16637702 DOI: 10.1021/jf052834c] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Traditionally, milk has been heat treated to control microorganisms and to alter its functionality, for example, to increase its heat stability. Pressure treatment has been considered as a possible alternative for microorganism control, but some of the functionality-related milk protein interactions have not been explored. The present study used two novel two-dimensional polyacrylamide gel electrophoresis (2D PAGE) methods to explore the differences in the irreversible disulfide bond changes among the milk proteins after four common heat treatments and after 30-min pressure treatments of milk at 200, 400, 600, and 800 MPa at ambient temperature (22 degrees C). The pasteurizing heat treatment (72 degrees C for 15 s) denatured and aggregated only a few minor whey proteins, but the high heat treatments (100 degrees C for 120 s, 120 degrees C for 120 s, and 140 degrees C for 5 s) formed disulfide-bonded aggregates that included a high proportion of all of the whey proteins and kappa-casein (kappa-CN) and a proportion of the alpha(s2)-CN. Pressure treatment of milk at 200 MPa caused beta-lactoglobulin (beta-LG) to form disulfide-bonded dimers and incorporated beta-LG into aggregates, probably disulfide-bonded to kappa-CN. The other whey proteins appeared to be less affected at 200 MPa for 30 min. In contrast, pressure treatment at 800 MPa incorporated beta-LG and most of the minor whey proteins, as well as kappa-CN and much of the alpha(s2)-CN, into aggregates. The accessibility of alpha(s2)-CN and formation of complexes involving alpha(s2)-CN, kappa-CN, and whey proteins in the pressure treated milk is an important novel finding. However, only some of the alpha-lactalbumin was denatured or incorporated into the large aggregates. These and other results show that the differences between the stabilities of the proteins and the accessibilities of the disulfide bonds of the proteins at high temperature or pressure affect the formation pathways that give the differences among the resultant aggregates, the sizes of the aggregates, and the product functionalities.
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Affiliation(s)
- Hasmukh A Patel
- Fonterra Research Centre, Private Bag 11 029, Palmerston North, New Zealand
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Bouguyon E, Beauvallet C, Huet JC, Chanat E. Disulphide bonds in casein micelle from milk. Biochem Biophys Res Commun 2006; 343:450-8. [PMID: 16546124 DOI: 10.1016/j.bbrc.2006.03.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2006] [Accepted: 03/02/2006] [Indexed: 11/21/2022]
Abstract
Mammary epithelial cells synthesised and secreted caseins, the major milk proteins in most mammals, as large aggregates called micelles into the alveolar lumen they surround. We investigated the implication of the highly conserved cysteine(s) of kappa-casein in disulphide bond formation in casein micelles from several species. Dimers were found in all milks studied, confirming previous observation in ruminants. More importantly, the study of interchain disulphide bridges in mouse and rat casein micelles revealed that any casein possessing a cysteine is engaged in disulphide bond interchange; these species express four or five cysteine-containing caseins, respectively. We found that the main rodent caseins form both homo- and heterodimers. Additionally, disulphide bond formation among milk proteins was specific since the interaction of the caseins with cysteine-containing whey proteins was not observed in native casein micelles.
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Affiliation(s)
- Edwige Bouguyon
- Institut National de la Recherche Agronomique, Laboratoire de Génomique et Physiologie de la Lactation, Jouy-en-Josas, F-78352, France
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Owusu-Apenten R. Colorimetric Analysis of Protein Sulfhydyl Groups in Milk: Applications and Processing Effects. Crit Rev Food Sci Nutr 2005; 45:1-23. [PMID: 15730186 DOI: 10.1080/10408690590900126] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Methods for protein sulfhydryl (SH) group analysis in food systems have been largely overlooked. Nevertheless, changes in SH group concentration affect both physical and nutritional characteristics of high protein foods and ingredients. Food scientists and technologists require improved understanding of protein SH chemistry in order to design processes that minimize loss of thiol groups. This article surveys colorimetric methods for food protein SH group analysis with applications to fluid milk and dried milk powder. Most colorimetric assays (chloromeribenzoate, pyridine disulfide, Nitrobenzo-2-oxa-1,3-diazole, papain reactivation assay, etc.) were found to be inferior to the Ellman method based on the use of 5,5'dithio (bis-2 nitro benzoic acid). Techniques for SH group analysis in fluid milk and dried milk powder are described, along with typical results, their interpretations, and current research related to processing effects and the role of milk SH content on a wider range of technological issues, such as development of cooked flavors, fouling and cleaning of plate heat exchanges, protein-protein interactions, and the storage stability. Finally, a number of areas requiring further research are presented.
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Affiliation(s)
- R Owusu-Apenten
- Department of Food Science, Borland Laboratory, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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Owusu-Apenten R, Chee C. Sulfhydryl group activation for commercial β-lactoglobulin measured using κ-casein 2-thio, 5′nitrobenzoic acid. Int Dairy J 2004. [DOI: 10.1016/s0958-6946(03)00177-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Guyomarc'h F, Law AJR, Dalgleish DG. Formation of soluble and micelle-bound protein aggregates in heated milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2003; 51:4652-4660. [PMID: 14705892 DOI: 10.1021/jf0211783] [Citation(s) in RCA: 140] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The formation of heat-induced aggregates of kappa-casein and denatured whey proteins was investigated in milk-based dairy mixtures containing casein micelles and serum proteins in different ratios. Both soluble and micelle-bound aggregates were isolated from the mixtures heated at 95 degrees C for 10 min, using size exclusion chromatography. Quantitative analysis of the protein composition of the aggregates by reverse phase high-performance liquid chromatography strongly suggested that primary aggregates of beta-lactoglobulin and alpha-lactalbumin in a 3 to 1 ratio were involved as well as kappa-casein, and alpha(s2)-casein in micellar aggregates. The results gave evidence that heat-induced dissociation of micellar kappa-casein was implicated in the formation of the soluble aggregates and indicated that a significant amount of kappa-casein was left unreacted after heating. The average size of the aggregates was 3.5-5.5 million Da, depending on the available kappa-casein or the casein:whey protein ratio in the mixtures. The size and density of these aggregates relative to those of casein micelles were discussed.
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Turhan K, Barbano D, Etzel M. Fractionation of Caseins by Anion-exchange Chromatography Using Food-grade Buffers. J Food Sci 2003. [DOI: 10.1111/j.1365-2621.2003.tb12294.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Abstract
High temperatures Induce certain changes in milk constituents, but the degree of these changes depends on both the temperature and time of heat treatment. The most pronounced changes take place in milk proteins. The forewarming of milk causes an increase in acidity, the precipitation of soluble Ca-phosphate, whey protein denaturation and coagulation, as well as the interaction with casein micelles, the Maillard browning reaction, the dephosphorylation of casein, the hydrolysis of casein micelles, changes in whey proteins, an extension of the rennet coagulation time and an exchange of the rheological properties of the acid and rennet casein gels, changes in the zeta-potential and casein micelle hydration, the interaction between the milk proteins and proteins of milk fat globule membrane.
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Bak M, Rasmussen LK, Petersen TE, Nielsen NC. Colloidal calcium phosphates in casein micelles studied by slow-speed-spinning 31P magic angle spinning solid-state nuclear magnetic resonance. J Dairy Sci 2001; 84:1310-9. [PMID: 11417687 DOI: 10.3168/jds.s0022-0302(01)70160-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The composition of bovine casein micelles was analyzed by 31P magic angle spinning solid-state nuclear magnetic resonance spectroscopy. By looking at isotropic and anisotropic 31P chemical shift parameters, resonance line shapes, the combination of single-pulse and 1H to 31P cross-polarization spectra, and comparison with spectra for various model compounds combined with multiple-component simulation and iterative fitting procedures, we were able to identify and quantify a variety of inorganic and organic phosphates in the micelles. These include phosphates from mobile and immobile inorganic hydroxyapatite-type phosphates as well as phosphates from kappa-casein and the Ca2+-binding phosphoserines from alphas1-, alphas2-, and beta-casein. This information is discussed in relation to previous knowledge and various models for the colloid formation.
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Affiliation(s)
- M Bak
- Department of Molecular and Structural Biology Science Park, University of Aarhus, Denmark
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