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Sonaglioni D, Libera V, Tombari E, Peters J, Natali F, Petrillo C, Comez L, Capaccioli S, Paciaroni A. Dynamic Personality of Proteins and Effect of the Molecular Environment. J Phys Chem Lett 2024; 15:5543-5548. [PMID: 38752860 DOI: 10.1021/acs.jpclett.4c00017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2024]
Abstract
Protein dynamics display distinct traits that are linked to their specific biological function. However, the interplay between intrinsic dynamics and the molecular environment on protein stability remains poorly understood. In this study, we investigate, by incoherent neutron scattering, the subnanosecond time scale dynamics of three model proteins: the mesophilic lysozyme, the thermophilic thermolysin, and the intrinsically disordered β-casein. Moreover, we address the influence of water, glycerol, and glucose, which create progressively more viscous matrices around the protein surface. By comparing the protein thermal fluctuations, we find that the internal dynamics of thermolysin are less affected by the environment compared to lysozyme and β-casein. We ascribe this behavior to the protein dynamic personality, i.e., to the stiffer dynamics of the thermophilic protein that contrasts the influence of the environment. Remarkably, lysozyme and thermolysin in all molecular environments reach a critical common flexibility when approaching the calorimetric melting temperature.
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Affiliation(s)
- Daniele Sonaglioni
- Physics Department, University of Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
| | - Valeria Libera
- Department of Physics and Geology, University of Perugia, via Alessandro Pascoli, 06123 Perugia, Italy
| | - Elpidio Tombari
- Istituto per i Processi Chimico-Fisici del CNR, via G. Moruzzi 1, 56124 Pisa, Italy
| | - Judith Peters
- Université Grenoble Alpes, CNRS, LiPhy, 38400 St Martin d'Heres, France
- Institut Laue Langevin, 38000 Grenoble, France
- Institut Universitaire de France, 75005 Paris, France
| | - Francesca Natali
- Institut Laue Langevin, 38000 Grenoble, France
- CNR-IOM and INSIDE@ILL c/o OGG, 71 avenue des Martyrs, CEDEX 9, 38042 Grenoble, France
| | - Caterina Petrillo
- Department of Physics and Geology, University of Perugia, via Alessandro Pascoli, 06123 Perugia, Italy
| | - Lucia Comez
- CNR-IOM, Department of Physics and Geology, University of Perugia, via Alessandro Pascoli, 06123 Perugia, Italy
| | - Simone Capaccioli
- Physics Department, University of Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
- Istituto per i Processi Chimico-Fisici del CNR, via G. Moruzzi 1, 56124 Pisa, Italy
- CISUP, Centro per l'Integrazione della Strumentazione dell'Università di Pisa, Lungarno Pacinotti 43, Pisa 56126, Italy
| | - Alessandro Paciaroni
- Department of Physics and Geology, University of Perugia, via Alessandro Pascoli, 06123 Perugia, Italy
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Duerasch A, Konieczny M, Henle T. Identification of the initial reactive sites of micellar and non-micellar casein exposed to microbial transglutaminase. Eur Food Res Technol 2022. [DOI: 10.1007/s00217-022-04069-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractTo investigate the influence of the internal micellar structure on the course of enzymatic cross-linking especially in the initial phase of the reaction, casein micelles isolated from raw milk via ultracentrifugation were incubated with microbial transglutaminase (mTG) in comparison with non-micellar sodium caseinate. Reactive lysine and glutamine residues were identified using a label-free approach, based on the identification of isopeptides within tryptic hydrolysates by targeted HRMS as well as manual monitoring of fragmentation spectra. Identified reactive sites were furthermore weighted by tracking the formation of isopeptides over an incubation time of 15, 30, 45 and 60 min, respectively. Fifteen isopeptides formed in the early stage of mTG cross-linking of caseins were identified and further specified concerning the position of lysine and glutamine residues involved in the reaction. The results revealed lysine K176 and glutamine Q175 of β-casein as the most reactive residues, which might be located in a highly flexible region of the molecule based on different possible reaction partners identified in this study. Except for the isopeptide αs1 K34–αs2 Q101 in sodium caseinate (SC), all reactive sites were detected in micellar and in non-micellar casein, indicating that the initial phase of enzymatic cross-linking is not affected by micellar aggregation of caseins.
Graphical abstract
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3
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Quantitative multivalent binding model of the structure, size distribution and composition of the casein micelles of cow milk. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2021.105292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Grifnée E, Kune C, Delvaux C, Quinton L, Far J, Mazzucchelli G, De Pauw E. Label-Free Higher Order Structure and Dynamic Investigation Method of Proteins in Solution Using an Enzymatic Reactor Coupled to Electrospray High-Resolution Mass Spectrometry Detection. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:284-295. [PMID: 34969249 DOI: 10.1021/jasms.1c00274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
For decades, structural analysis of proteins have received considerable attention, from their sequencing to the determination of their 3D structures either in the free state (e.g., no host-guest system, apoproteins) or (non)covalently bound complexes. The elucidation of the 3D structures and the mapping of intra- and intermolecular interactions are valuable sources of information to understand the physicochemical properties of such systems. X-ray crystallography and nuclear magnetic resonance are methods of choice for obtaining structures at the atomic level. Nonetheless, they still present drawbacks which limit their use to highly purified systems in a relatively high amount. On the contrary, mass spectrometry (MS) has become a powerful tool thanks to its selectivity, sensitivity, and the development of structural methods both at the global shape and the residue level. The combination of several MS-based methods is mandatory to fully assign a putative structure in combination with computational chemistry and bioinformatics. In that context, we propose a strategy which complements the existing methods of structural studies (e.g., circular dichroism, hydrogen/deuterium exchange and cross-links experiments, nuclear magnetic resonance). The workflow is based on the collection of structural information on proteins from the apparition rates and the time of appearance of released peptides generated by a protease in controlled experimental conditions with online detection by electrospray high-resolution mass spectrometry. Nondenaturing, partially or fully denatured proteins were digested by the enzymatic reactor, i.e., β-lactoglobulin, cytochrome c, and β-casein. The collected data are interpreted with regard to the kinetic schemes with time-dependent rates of the enzymatic digestion established beforehand, considering kinetics parameters in the Michaelis-Menten formalism including kcat (the turnover number), k1 (formation of the enzyme-substrate complex), k-1 (dissociation of the enzyme-substrate complex), koff (local refolding of the protein around the cleavage site), and kon (local unfolding of the protein around the cleavage site). Solvent-accessible surface analysis through digestion kinetics was also investigated. The initial apparition rates of released peptides varied according to the protein state (folded vs denatured) and informs the koff/kon ratio around the cleavage site. On the other hand, the time of appearance of a given peptide is related to its solvent accessibility and to the resilience of the residual protein structure in solution. Temperature-dependent digestion experiments allowed estimation of the type of secondary structures around the cleavage site.
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Affiliation(s)
- Elodie Grifnée
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Christopher Kune
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Cédric Delvaux
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Loïc Quinton
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Johann Far
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Gabriel Mazzucchelli
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
| | - Edwin De Pauw
- Mass Spectrometry Laboratory, MolSys Research Unit, Quartier Agora, University of Liège, Allée du Six Août 11, B-4000 Liège, Belgium
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Nakagawa H, Appavou MS, Wuttke J, Zamponi M, Holderer O, Schrader TE, Richter D, Doster W. Nanosecond structural dynamics of intrinsically disordered β-casein micelles by neutron spectroscopy. Biophys J 2021; 120:5408-5420. [PMID: 34717964 PMCID: PMC8715185 DOI: 10.1016/j.bpj.2021.10.032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 09/17/2021] [Accepted: 10/13/2021] [Indexed: 10/20/2022] Open
Abstract
β-casein undergoes a reversible endothermic self-association, forming protein micelles of limited size. In its functional state, a single β-casein monomer is unfolded, which creates a high structural flexibility, which is supposed to play a major role in preventing the precipitation of calcium phosphate particles. We characterize the structural flexibility in terms of nanosecond molecular motions, depending on the temperature by quasielastic neutron scattering. Our major questions are: Does the self-association reduce the chain flexibility? How does the dynamic spectrum of disordered caseins differ from a compactly globular protein? How does the dynamic spectrum of β-casein in solution differ from that of a protein in hydrated powder states? We report on two relaxation processes on a nanosecond and a sub-nanosecond timescale for β-casein in solution. Both processes are analyzed by Brownian oscillator model, by which the spring constant can be defined in the isotropic parabolic potential. The slower process, which is analyzed by neutron spin echo, seems a characteristic feature of the unfolded structure. It requires bulk solvent and is not seen in hydrated protein powders. The faster process, which is analyzed by neutron backscattering, has a smaller amplitude and requires hydration water, which is also observed with folded proteins in the hydrated state. The self-association had no significant influence on internal relaxation, and thus, a β-casein protein monomer flexibility is preserved in the micelle. We derive spring constants of the faster and slower motions of β-caseins in solution and compared them with those of some proteins in various states (folded or hydrated powder).
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Affiliation(s)
- Hiroshi Nakagawa
- Materials Sciences Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan; Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany; J-PARC Center, Japan Atomic Energy Agency, Tokai, Ibaraki, Japan.
| | - Marie-Sousai Appavou
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Joachim Wuttke
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Michaela Zamponi
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Olaf Holderer
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Tobias E Schrader
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Dieter Richter
- Forschungszentrum Jülich, Jülich Centre for Neutron Science at Heinz Maier-Leibnitz Zentrum, Garching, Germany
| | - Wolfgang Doster
- Technische Universität München, Physik-Department, Garching, Germany
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Sun Y, Tai Z, Yan T, Dai Y, Hemar Y, Li N. Unveiling the structure of the primary caseinate particle using small-angle X-ray scattering and simulation methodologies. Food Res Int 2021; 149:110653. [PMID: 34600655 DOI: 10.1016/j.foodres.2021.110653] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/11/2021] [Accepted: 08/17/2021] [Indexed: 11/27/2022]
Abstract
The low-resolution structure of casein (CN) clusters in sodium caseinate (NaCas) solution and its conformational dynamics were obtained by size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), small-angle X-ray scattering (SAXS), and molecular dynamics (MD) simulations. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE revealed that the casein clusters consisted predominantly of α- and β-CN complexes, and a trace amount of κ-CN. The AUC analysis indicated that the casein clusters were composed of 34.6% of casein monomers, 19.2%, 20.4%, and 25.8% of complexes with molar weight (Mw) of ~50.3, ~70.6, and ~133 kDa, respectively. The volume fractions of components in casein clusters were quantified as 64.3% of αs1-β-αs2-CN, 22.3% of αs1-CN, 8.5% of αs2-CN, and 4.4% of αs1-αs2-CN, respectively. The ensemble optimization method (EOM) gave a fitting result where αs1-β-αs2-CN species coexisted in ~35.3% under compact conformation and ~64.7% in elongated conformation in solution. The three-dimensional structures of αs1-β-αs2-CN from EOM showed a good overlay on the casein clusters ab initio model obtained from DAMMIN and DAMMIX program. MD simulations revealed that αs1-β-αs2-CN underwent a conformational change from the elongated state into the compact state within the initial 200 ns of simulations. The addition of nonionic surfactants affected little the backbone-to-backbone interactions in the formation of the casein clusters. We propose that αs1-CN, β-CN, αs2-CN, and κ-CN associated in consecutive steps into casein clusters, and a trace of κ-CN may be located at the surface of the assemblies limiting the growth of casein aggregates.
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Affiliation(s)
- Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China.
| | - Zhonghong Tai
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Tingting Yan
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Yiqi Dai
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Yacine Hemar
- Catalyst Tec Limited., 16 Beatrice Tinsley Cresecnt, Rosedale 0632, Auckland, New Zealand; International Joint Research Laboratory for Functional Dairy Protein Ingredients, U.S.-China, People's Republic of China
| | - Na Li
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, CAS, No.333, Haike Road, Shanghai, Shanghai 201210, People's Republic of China.
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France TC, Kelly AL, Crowley SV, O’Mahony JA. Cold Microfiltration as an Enabler of Sustainable Dairy Protein Ingredient Innovation. Foods 2021; 10:foods10092091. [PMID: 34574201 PMCID: PMC8468473 DOI: 10.3390/foods10092091] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/29/2021] [Accepted: 09/01/2021] [Indexed: 11/22/2022] Open
Abstract
Classically, microfiltration (0.1–0.5 µm) of bovine skim milk is performed at warm temperatures (45–55 °C), to produce micellar casein and milk-derived whey protein ingredients. Microfiltration at these temperatures is associated with high initial permeate flux and allows for the retention of the casein fraction, resulting in a whey protein fraction of high purity. Increasingly, however, the microfiltration of skim milk and other dairy streams at low temperatures (≤20 °C) is being used in the dairy industry. The trend towards cold filtration has arisen due to associated benefits of improved microbial quality and reduced fouling, allowing for extended processing times, improved product quality and opportunities for more sustainable processing. Performing microfiltration of skim milk at low temperatures also alters the protein profile and mineral composition of the resulting processing streams, allowing for the generation of new ingredients. However, the use of low processing temperatures is associated with high mechanical energy consumption to compensate for the increased viscosity, and thermal energy consumption for inline cooling, impacting the sustainability of the process. This review will examine the differences between warm and cold microfiltration in terms of membrane performance, partitioning of bovine milk constituents, microbial growth, ingredient innovation and process sustainability.
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France TC, Bot F, Kelly AL, Crowley SV, O'Mahony JA. The influence of temperature on filtration performance and fouling during cold microfiltration of skim milk. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.118256] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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9
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Wijaya W, Khan S, Madsen M, Møller MS, Maria Rovers TA, Jæger TC, Ipsen R, Westh P, Svensson B. Tunable mixed micellization of β-casein in the presence of κ-casein. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106459] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Cheng H, Dong H, Wusigale, Liang L. A comparison of β-casein complexes and micelles as vehicles for trans-/cis-resveratrol. Food Chem 2020; 330:127209. [PMID: 32535314 DOI: 10.1016/j.foodchem.2020.127209] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Revised: 05/30/2020] [Accepted: 05/31/2020] [Indexed: 11/25/2022]
Abstract
Bovine β-casein is an amphiphilic protein that exists as a monomer and self-organizes into micelles in aqueous solution. The protein has been used as natural vehicles for bioactives. Trans-resveratrol has received significant attention due to its vast health benefits and conversion to cis-isomer during processing and storage. However, cis-isomer has not yet gained as much attention as that of trans-isomer. In this study, the interaction of β-casein with trans- and cis-resveratrol was characterized. Trans-resveratrol exhibited a higher affinity for β-casein than cis-isomer, and β-casein could bind two isomers simultaneously to form protein-diligand complexes. Both trans- and cis-isomers could be encapsulated into β-casein micelles with encapsulation efficiencies of ~69% and ~57%, respectively. The β-casein micelles could delay photo-isomerization of trans-isomer to cis-isomer, while β-casein-ligand complex showed a better protective effect for both isomers during storage than β-casein micelles. These results might be useful for the development of protein-based carriers for the polyphenols.
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Affiliation(s)
- Hao Cheng
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Huanhuan Dong
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Wusigale
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China
| | - Li Liang
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China; School of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu, China.
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Li M, Fokkink R, Ni Y, Kleijn JM. Bovine beta-casein micelles as delivery systems for hydrophobic flavonoids. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.06.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12
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Li M, Auty MA, Crowley SV, Kelly AL, O'Mahony JA, Brodkorb A. Self-association of bovine β-casein as influenced by calcium chloride, buffer type and temperature. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2018.09.035] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Sun Y, Zhang J, Wang H, Wang T, Cheng H, Yu B, Oliveira CL. Sulfate dodecyl sodium-induced stability of a model intrinsically disordered protein, bovine casein. Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2018.03.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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14
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Bhatt H, Cucheval A, Coker C, Patel H, Carr A, Bennett R. Effect of micellar structure of casein and its modification on plasmin-induced hydrolysis. Int Dairy J 2017. [DOI: 10.1016/j.idairyj.2017.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Melnikova DL, Skirda VD, Nesmelova IV. Effect of Intrinsic Disorder and Self-Association on the Translational Diffusion of Proteins: The Case of α-Casein. J Phys Chem B 2017; 121:2980-2988. [PMID: 28346777 DOI: 10.1021/acs.jpcb.7b00772] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Translational diffusion is the major mode of macromolecular transport in leaving organisms, and therefore it is vital to many biological and biotechnological processes. Although translational diffusion of proteins has received considerable theoretical and experimental scrutiny, much of that attention has been directed toward the description of globular proteins. The translational diffusion of intrinsically disordered proteins (IDPs), however, is much less studied. Here, we use a pulsed-gradient nuclear magnetic resonance technique (PFG NMR) to investigate the translational diffusion of a disordered protein in a wide range of concentrations using α-casein that belongs to the class of natively disordered proteins as an example.
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Affiliation(s)
- Daria L Melnikova
- Department of Physics, Kazan Federal University , Kazan 420011, Russia
| | - Vladimir D Skirda
- Department of Physics, Kazan Federal University , Kazan 420011, Russia
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17
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Milk Protein Polymer and Its Application in Environmentally Safe Adhesives. Polymers (Basel) 2016; 8:polym8090324. [PMID: 30974597 PMCID: PMC6432148 DOI: 10.3390/polym8090324] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/22/2016] [Accepted: 08/23/2016] [Indexed: 11/17/2022] Open
Abstract
Milk proteins (caseins and whey proteins) are important protein sources for human nutrition; in addition, they possess important natural polymers. These protein molecules can be modified by physical, chemical, and/or enzymatic means. Casein is one of the oldest natural polymers, used for adhesives, dating back to thousands years ago. Research on milk-protein-based adhesives is still ongoing. This article deals with the chemistry and structure of milk protein polymers, and examples of uses in environmentally-safe adhesives. These are promising routes in the exploration of the broad application of milk proteins.
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Turovsky T, Khalfin R, Kababya S, Schmidt A, Barenholz Y, Danino D. Celecoxib Encapsulation in β-Casein Micelles: Structure, Interactions, and Conformation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:7183-7192. [PMID: 26068530 DOI: 10.1021/acs.langmuir.5b01397] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
β-Casein is a 24 kDa natural protein that has an open conformation and almost no folded or secondary structure, and thus is classified as an intrinsically unstructured protein. At neutral pH, β-casein has an amphiphilic character. Therefore, in contrast to most unstructured proteins that remain monomeric in solution, β-casein self-assembles into well-defined core-shell micelles. We recently developed these micelles as potential carriers for oral administration of poorly water-soluble pharmaceuticals, using celecoxib as a model drug. Herein we present deep and precise insight into the physicochemical characteristics of the protein-drug formulation, both in bulk solution and in dry form, emphasizing drug conformation, packing properties and aggregation state. In addition, the formulation is extensively studied in terms of structure and morphology, protein/drug interactions and physical stability. Particularly, NMR measurements indicated strong drug-protein interactions and noncrystalline drug conformation, which is expected to improve drug solubility and bioavailability. Small-angle X-ray scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM) were combined for nanostructural characterization, proving that drug-protein interactions lead to well-defined spheroidal micelles that become puffier and denser upon drug loading. Dynamice light scattering (DLS), turbidity measurements, and visual observations complemented the analysis for determining formulation structure, interactions, and stability. Additionally, it was shown that the loaded micelles retain their properties through freeze-drying and rehydration, providing long-term physical and chemical stability. Altogether, the formulation seems greatly promising for oral drug delivery.
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Affiliation(s)
- Tanya Turovsky
- †Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Rafail Khalfin
- ‡Department of Chemical Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Shifi Kababya
- §Shulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Asher Schmidt
- §Shulich Faculty of Chemistry, Technion - Israel Institute of Technology, Haifa 3200003, Israel
| | - Yechezkel Barenholz
- ∥Laboratory of Membrane and Liposome Research, IMRIC, the Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel
| | - Dganit Danino
- †Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 3200003, Israel
- ⊥Department of Biotechnology and Food Engineering, Technion - Israel Institute of Technology, Haifa 3200003, Israel
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Perticaroli S, Nickels JD, Ehlers G, Mamontov E, Sokolov AP. Dynamics and rigidity in an intrinsically disordered protein, β-casein. J Phys Chem B 2014; 118:7317-26. [PMID: 24918971 DOI: 10.1021/jp503788r] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The emergence of intrinsically disordered proteins (IDPs) as a recognized structural class has forced the community to confront a new paradigm of structure, dynamics, and mechanical properties for proteins. We present novel data on the similarities and differences in the dynamics and nanomechanical properties of IDPs and other biomacromolecules on the picosecond time scale. An IDP, β-casein (CAS), has been studied in a calcium bound and unbound state using neutron and light scattering techniques. We show that CAS partially folds and stiffens upon calcium binding, but in the unfolded state, it is softer than folded proteins such as green fluorescence protein (GFP). We also see that some localized diffusive motions in CAS have a larger amplitude than in GFP at this time scale but are still smaller than those observed in tRNA. In spite of these differences, CAS dynamics are consistent with the classes of motions seen in folded protein on this time scale.
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Affiliation(s)
- Stefania Perticaroli
- Joint Institute for Neutron Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States
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Pinto MS, Léonil J, Henry G, Cauty C, Carvalho AF, Bouhallab S. Heating and glycation of β-lactoglobulin and β-casein: Aggregation and in vitro digestion. Food Res Int 2014. [DOI: 10.1016/j.foodres.2013.10.030] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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21
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Effect of calcium ions on both the co-assembly of αs-casein with soy phosphatidylcholine and the novel functionality of their complex particles. Food Hydrocoll 2014. [DOI: 10.1016/j.foodhyd.2013.03.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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22
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Ossowski S, Jackson A, Obiols-Rabasa M, Holt C, Lenton S, Porcar L, Paulsson M, Nylander T. Aggregation behavior of bovine κ- and β-casein studied with small angle neutron scattering, light scattering, and cryogenic transmission electron microscopy. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13577-13589. [PMID: 22924693 DOI: 10.1021/la302416p] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
In the native bovine casein micelle the calcium sensitive caseins (α(S1)-, α(S2)- and β-casein) sequester amorphous calcium phosphate in nanometer-sized clusters, whereas the calcium-insensitive κ-casein limits the growth of the micelle. In this paper, we further investigate the self-association of κ- and β-casein, which are two of the key proteins that control the substructure of the milk casein micelle, using neutron and light scattering techniques and cryogenic transmission electron microscopy. Results demonstrate that κ-casein can, apart from the known self-assembly, form amyloid-like fibrils already at temperatures of 25 °C when subject to agitation. This extended aggregation behavior of κ-casein is inhibited by β-casein, as reported by others. These findings have implications for the structure and stability of casein micelles. The neutron scattering data was used to gain information on the self-assembly structure of κ-casein. β-Casein shows similar self-association behavior as κ-casein, but unlike κ-casein, the self-association exhibits temperature dependence within the studied temperatures (6 and 25 °C). Here, we will discuss our extended study of the known self-assembly of casein in the context of the fibrillation of κ-casein.
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Affiliation(s)
- Sofie Ossowski
- Division of Physical Chemistry, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
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Bachar M, Mandelbaum A, Portnaya I, Perlstein H, Even-Chen S, Barenholz Y, Danino D. Development and characterization of a novel drug nanocarrier for oral delivery, based on self-assembled β-casein micelles. J Control Release 2012; 160:164-71. [DOI: 10.1016/j.jconrel.2012.01.004] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Revised: 01/05/2012] [Accepted: 01/06/2012] [Indexed: 12/14/2022]
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Shapira A, Assaraf YG, Livney YD. Beta-casein nanovehicles for oral delivery of chemotherapeutic drugs. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2010; 6:119-26. [DOI: 10.1016/j.nano.2009.06.006] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2009] [Revised: 05/17/2009] [Accepted: 06/01/2009] [Indexed: 11/26/2022]
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25
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26
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Mineral and protein equilibria between the colloidal and soluble phases of milk at low temperature. J DAIRY RES 2009. [DOI: 10.1017/s0022029900021890] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SummaryMechanisms controlling exchange and partition of minerals and β-casein between micellar and soluble phases during cooling have been studied using suspensions of milk proteins of varying concentrations in the presence of aqueous phases having varying mineral compositions. In these studies the final equilibrium between Ca and phosphate was found to be regulated by formation of Ca phosphates of varying solubilities. The effect of the total casein level on mineral and protein equilibria was also studied. In milk, part of the β-casein content is bound to micelles by hydrophobic bonds; the proportion present in this form was increased by spontaneous micellar demineralization during cooling as well as by addition of a complexant to milk. At low temperatures, an equilibrium between the micellar and the monomeric states was reached which depends upon the total casein level and on the hydrophobic-bonded β-casein content. Not all of these hydrophobic bonds were broken when milk was cooled.
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Abstract
SUMMARYThe proteins of bovine milk are the best-characterized food-protein system. Lactoproteins, which have high biological value, contribute ∼25% of dietary protein in North West Europe, North America and Oceania. However, in protein-rich western diets, milk proteins are frequently more highly valued for their functional properties than for their nutritional qualities. The remarkably high heat stability of the caseinate system permits the manufacture of a range of sterilized, concentrated and dehydrated products while its gelation on very limited proteolysis is the basis of cheese manufacture. Skim-milk powders, caseinates and whey protein concentrates are the most flexible and widely used functional proteins in food processing.This communication reviews recent studies on milk proteins with respect to molecular and colloidal properties; coagulation by Ca2+, heat and ethanol; and functional properties and their chemical and enzymic modification.
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Gaudin JC, Le Parc A, Castrec B, Ropers MH, Choiset Y, Shchutskaya J, Yousefi R, Muronetz VI, Zuev Y, Chobert JM, Haertlé T. Engineering of caseins and modulation of their structures and interactions. Biotechnol Adv 2009; 27:1124-1131. [PMID: 19463935 DOI: 10.1016/j.biotechadv.2009.05.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Beta-casein (beta-CN) is a milk protein widely used in food industries because of its mild emulsifying properties due to its amphiphilicity. However, the elements determining its micellization behavior in solution and interfacial behavior at the air-water interface are not well known. In order to study how the forced dimerisation influences functional properties of beta-CN, recombinant wild-type beta-CN was produced and distal cysteinylated forms of recombinant beta-CN were engineered. We show that 1) cysteinylated beta-CN formed mainly dimers bridged by disulfide bonds; 2) the process of dimerization adds to the micellization process with temperature and is poorly reversible; 3) covalent disulfide linkage forms at the air-water interface at a lower temperature than in bulk. In conclusion, the location of the cysteinylation in the C-terminus or N-terminus or both is of importance for the properties of beta-CN.
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Affiliation(s)
| | - Annabelle Le Parc
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France
| | - Benoit Castrec
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France
| | | | - Yvan Choiset
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France
| | - Juliya Shchutskaya
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France; Belozersky Institute of Physico-Chemical Biology, Moscow State University, Lenin's Hills, Moscow, 119992, Russia
| | - Reza Yousefi
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France; Department of Biology, College of Sciences, Shiraz University, Shiraz, 71454, Iran
| | - Vladimir I Muronetz
- Belozersky Institute of Physico-Chemical Biology, Moscow State University, Lenin's Hills, Moscow, 119992, Russia
| | - Yuri Zuev
- Kazan Institute of Biochemistry and Biophysics, Kazan, P.O. Box 30, 420111, Russia
| | - Jean-Marc Chobert
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France
| | - Thomas Haertlé
- UR 1268 Biopolymères Interactions Assemblages, INRA, 44300 Nantes, France.
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Moitzi C, Portnaya I, Glatter O, Ramon O, Danino D. Effect of temperature on self-assembly of bovine beta-casein above and below isoelectric pH. Structural analysis by cryogenic-transmission electron microscopy and small-angle X-ray scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:3020-3029. [PMID: 18327957 DOI: 10.1021/la702802a] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
beta-Casein is one of the main proteins in milk, recently classified as an intrinsically unstructured protein. At neutral pH, it is composed of a highly polar N-terminus domain and a hydrophobic C-terminus tail. This amphiphilic block-copolymer-like structure leads to self-organization of the protein monomers into defined micelles. Recently, it has been shown that at room temperature, beta-casein also self-organizes into micelles in an acidic environment, but the effect of temperature on the micelles' formation and properties at the low pH regime were not explored. In the present study, we used two complementary techniques, cryogenic-transmission electron microscopy (cryo-TEM) and small-angle X-ray scattering (SAXS), to characterize at high-resolution the micelles' shape, dimensions, and aggregation numbers and to determine how these properties are affected by temperature between 1 and 40 degrees C. Two different regimes were studied: highly acidic pH where the protein is cationic, and neutral pH, where it is anionic. We found that flat disk-like micelles with low aggregation numbers formed at low temperature in the two pH regimes. Close to neutral pH increase in temperature involves a transition in the micelles' shape and dimensions from flat disks to bulky, almost spheroidal micelles, coupled with a sharp increase in the micelles' aggregation number. In contrast, no effects on the micelles' morphology or aggregation number were detected in the acidic environment within the entire temperature range studied. The self-organization into disk micelles and the lack of effect of temperature in the acidic environment are linked to the unstructured character of the protein and to the charge distribution map. The latter indicates that below the isoelectric pH (pI), beta-casein loses the distinct separation of hydrophobic and hydrophilic domains, thereby suggesting that it may no longer be considered as a classical head-tail block-copolymer amphiphile as in neutral pH.
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Affiliation(s)
- Christian Moitzi
- Institute of Chemistry and Physical Chemistry, University of Graz, Graz A-8010, Austria
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30
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Modifications of the charges at the N-terminus of bovine β-casein: Consequences on its structure and its micellisation. Food Hydrocoll 2007. [DOI: 10.1016/j.foodhyd.2006.03.007] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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31
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Aschi A, Gharbi A, Daoud M, Douillard R, Calmettes P. Study of structure and scaling behavior of chemically unfolded β-casein by means of small-angle neutron scattering. POLYM INT 2007. [DOI: 10.1002/pi.2176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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32
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Burova TV, Grinberg NV, Grinberg VY, Usov AI, Tolstoguzov VB, Kruif CGD. Conformational Changes in ι- and κ-Carrageenans Induced by Complex Formation with Bovine β-Casein. Biomacromolecules 2006; 8:368-75. [PMID: 17291059 DOI: 10.1021/bm060761f] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The formation of electrostatic complexes between beta-casein and iota- and kappa-carrageenans is well-known. However, the molecular mechanism of the complexation has yet to be determined, particularly with respect to the conformational changes of the interacting macromolecules. High-sensitivity differential scanning calorimetry was used to study beta-casein/carrageenan mixtures at different pH values (3.0 to 7.5), ionic strengths (0.03 and 0.15 M), and various molar protein/polysaccharide ratios (3-400). The effects of these variables on the temperature, enthalpy, and width of the helix-coil transition of iota- and kappa-carrageenans were investigated. Neither pH nor the protein/polysaccharide ratio influenced the transition temperature of either carrageenan in the complexes. However, the transition enthalpy of both carrageenans in complexes with beta-casein decreased to zero with both decreasing pH and increasing protein/polysaccharide ratio. This may reflect an unwinding of the polysaccharide double helix induced by beta-casein, a conformational change which is fully reversible in conditions of sufficiently high ionic strength. The interaction of beta-casein with iota- and kappa-carrageenans was approximated in terms of the model of binding of large ligands to macromolecules, that provides the binding constants for these biopolymers.
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Affiliation(s)
- Tatiana V Burova
- N.M. Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Vavilov St. 28, 119991, Moscow, Russia.
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Portnaya I, Cogan U, Livney YD, Ramon O, Shimoni K, Rosenberg M, Danino D. Micellization of bovine beta-casein studied by isothermal titration microcalorimetry and cryogenic transmission electron microscopy. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2006; 54:5555-61. [PMID: 16848545 DOI: 10.1021/jf060119c] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The association behavior, critical micellization concentration (CMC), and enthalpy of demicellization (DeltaHdemic) of bovine beta-casein were studied, for the first time by isothermal titration calorimetry, in a pH 7.0 phosphate buffer with 0.1 ionic strength and in pure water. In the buffer solutions, the CMC decreased asymptotically from 0.15 to 0.006 mM as the temperature was raised from 16 to 45 degrees C. DeltaHdemic decreased with increasing temperature between 16 and 28 degrees C but increased from 28 to 45 degrees C. Thermodynamic analysis below 30 degrees C is consistent with the Kegeles shell model, which suggests a stepwise association process. At higher temperatures, this model exhibits limitations, and the micellization becomes much more cooperative. The CMC values in water, measured between 17 and 28 degrees C, decreased with increasing temperature and, expectedly, were higher than those found in the buffer solutions. beta-Casein micelles were visualized and characterized, for the first time in their hydrated state, using advanced digital-imaging cryogenic transmission electron microscopy. The images revealed small, oblate micelles, about approximately 13 nm in diameter. The micelles shape and dimensions remained nearly constant in the temperature range of 24-35 degrees C.
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Affiliation(s)
- Irina Portnaya
- Department of Biotechnology and Food Engineering and Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, 32000 Israel
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Qi PX, Wickham ED, Piotrowski EG, Fagerquist CK, Farrell HM. Implication of C-terminal deletion on the structure and stability of bovine beta-casein. Protein J 2006; 24:431-44. [PMID: 16328736 DOI: 10.1007/s10930-005-7639-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Bovine beta-casein (beta-CN) with its C-terminal truncated by chymosin digestion, beta-CN-(f1-192), was examined and characterized using circular dichroism (CD) under various temperature conditions. CONTIN/LL analysis of the CD data revealed significant secondary structure disruption in beta-CN-(f1-192) relative to its parent protein,beta-CN, in the temperature range (5 degrees to 70 degrees C) studied. Near-UV CD spectra indicated significant temperature dependent structural changes. Analytical ultracentrifugation results showed significant reduction but not complete abolishment of self-association in beta-CN-(f1-192) compared to whole beta-casein at 2 degrees -37 degrees C. Furthermore, binding experiments with the common hydrophobic probe - 8-anilino-1- naphthalene sulfonic acid (ANS) illustrated that beta-CN-(f1-192) is nearly incapable of binding to ANS relative to whole beta-CN, suggesting a nearly complete open overall tertiary structure brought about by the C-terminal truncation. It has been demonstrated clearly that the tail peptide beta-CN-(f193-209) is important in maintaining the hydrophobic core of beta-CN but the residual association observed argues for a minor role for other sites as well.
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Affiliation(s)
- Phoebe X Qi
- U. S. Department of Agriculture, Eastern Regional Research Center, Agricultural Research Service, 600 East Mermaid Lane, Wyndmoor, PA, 19038, USA.
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35
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Panouillé M, Durand D, Nicolai T. Jamming and Gelation of Dense β-Casein Micelle Suspensions. Biomacromolecules 2005; 6:3107-11. [PMID: 16283734 DOI: 10.1021/bm050438x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rheology of dense suspensions of beta-casein micelles is investigated at pH 6. For a given temperature, the viscosity increases dramatically at a critical concentration (Cc) of about 100 g/L due to jamming of the micelles. For a given concentration close to and above Cc, the viscosity of dense suspensions decreases strongly with increasing temperature because Cc increases. The suspensions show weak shear thickening followed by strong shear thinning. At lower pH, that is, closer to the isoelectric point, spontaneous gelation is observed, which is favored by lowering the temperature and addition of sodium polyphosphate. The gelation process is studied at pH 5.5 by rheology and light scattering.
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Affiliation(s)
- Maud Panouillé
- Polymères, Colloïdes, Interfaces, Unite mixté de recherche, Centre National de la Recherche Scientifique, Université du Maine, 72085 le Mans Cedex 9, France
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36
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Tompa P. The interplay between structure and function in intrinsically unstructured proteins. FEBS Lett 2005; 579:3346-54. [PMID: 15943980 DOI: 10.1016/j.febslet.2005.03.072] [Citation(s) in RCA: 558] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2005] [Indexed: 11/20/2022]
Abstract
Intrinsically unstructured proteins (IUPs) are common in various proteomes and occupy a unique structural and functional niche in which function is directly linked to structural disorder. The evidence that these proteins exist without a well-defined folded structure in vitro is compelling, and justifies considering them a separate class within the protein world. In this paper, novel advances in the rapidly advancing field of IUPs are reviewed, with the major attention directed to the evidence of their unfolded character in vivo, the interplay of their residual structure and their various functional modes and the functional benefits their malleable structural state provides. Via all these details, it is demonstrated that in only a couple of years after its conception, the idea of protein disorder has already come of age and transformed our basic concepts of protein structure and function.
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Affiliation(s)
- Peter Tompa
- Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 7, H-1518 Budapest, Hungary.
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Cosman NP, Fatih K, Roscoe SG. Electrochemical impedance spectroscopy study of the adsorption behaviour of α-lactalbumin and β-casein at stainless steel. J Electroanal Chem (Lausanne) 2005. [DOI: 10.1016/j.jelechem.2004.08.007] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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38
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Livney YD, Schwan AL, Dalgleish DG. A Study of β-Casein Tertiary Structure by Intramolecular Crosslinking and Mass Spectrometry. J Dairy Sci 2004; 87:3638-47. [PMID: 15483147 DOI: 10.3168/jds.s0022-0302(04)73502-x] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The objective of this study was to obtain experimental evidence to extend the discussion on the 3-D structure of beta-casein (beta-CN). The approach involved the preparation of homobifunctional crosslinkers, bis(sulfosuccinimidyl) derivatives of dicarboxylic acids of several lengths, which specifically react with primary amines of lysinyl residues or the N-terminal in the protein. The intramolecular crosslinks formed were determined by enzymatic digestion and by matrix-assisted laser desorption and ionization time-of-flight mass spectrometry combined with comparison against the theoretical digestion patterns. This procedure allowed the measurement of distances between the crosslinked residues. Ten different masses arising from 8 different specific intramolecular crosslinks were identified. Of these, 5 crosslinks were in good agreement with a published model (Kumosinski et al., 1993). Two other crosslinks each connected 2 residues that are much closer together, according to the model, than the maximum length of the crosslink. However, one of the crosslinks apparently connected 2 residues that are predicted by the model to be 16.7 A farther apart than the crosslink's stretched length. This disparity might be explained by structural flexibility. The structure expressed by the model is probably one of several energetically favorable conformations of the beta-CN molecule, whose structure is best described as rheomorphic rather than either a fixed structure or a random coil.
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Affiliation(s)
- Y D Livney
- Department of Food Science, University of Guelph, ON, Canada N1G 2W1
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39
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Zhong Q, Daubert CR, Velev OD. Cooling effects on a model rennet casein gel system: part I. Rheological characterization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2004; 20:7399-7405. [PMID: 15323482 DOI: 10.1021/la036147w] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The gelation of a model rennet casein system was studied during cooling at different rates. During cooling, casein network structure development was proposed to evolve over a few steps at different length scales: molecules, particles, flocs, or network. Rennet casein flocs are fractal in nature, and fractal dimension and floc size are two variables affecting the rheology and microstructure of a rennet casein gel. Casein structure formation during cooling from 80 to 5 degrees C at four different rates (0.5, 0.1, 0.05, and 0.025 degrees C/min) was monitored by dynamic rheological tests, and a stronger gel developed at a slower cooling rate. During different cooling schedules, similar fractal dimensions were observed due to a lack of difference in the colloidal interactions. Differences among rheological data were possibly caused by variability in floc size, as observed in the second part of this paper. A larger number of smaller-sized flocs enabled gelation at a higher temperature and created a stronger network at a slower cooling rate. Controlling cooling schemes thus provides an approach for manipulating casein gelation and the microstructure for a system of fixed chemical compositions.
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Affiliation(s)
- Qixin Zhong
- Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695, USA
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40
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Smyth E, Clegg RA, Holt C. A biological perspective on the structure and function of caseins and casein micelles. INT J DAIRY TECHNOL 2004. [DOI: 10.1111/j.1471-0307.2004.00141.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Affiliation(s)
- Gordon A Morris
- Division of Food Sciences, School of BioSciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK.
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O'Connell J, de Kruif C. β-Casein micelles; cross-linking with transglutaminase. Colloids Surf A Physicochem Eng Asp 2003. [DOI: 10.1016/s0927-7757(02)00503-4] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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44
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Abstract
The association behavior of beta-casein, a protein with a distinct amphipathic character, was studied. beta-Casein exhibits markedly temperature-dependent association behavior; at low temperatures (<10-15 degrees C), monomers predominate, but as the temperature is increased, monomers associate, via hydrophobic bonding, into micelles. beta-Casein micelles have a hydrodynamic radius of approximately 12 nm, a radius of gyration of approximately 8.3 nm, and an interaction radius of approximately 15 nm. These data are fully consistent with a previous fluffy particle. The association behavior of beta-casein is also strongly affected by concentration and solvent quality. At low concentrations beta-casein exhibits a critical micelle concentration (CMC) of approximately 0.05%, w/v, at 40 degrees C. In the presence of 6 M urea the temperature dependence of beta-casein's association behavior is eliminated, leaving monomers predominantly. Temperature-dependent transformations in micelle morphology can be explained by changes in solvent quality, i.e., the temperature-protein hydrophobicity and temperature-voluminosity profiles of beta-casein. The results obtained are consistent with the shell model as developed by Kegeles, in which a distribution of micelle sizes is formed. They contrast with the traditional description of the micellization of beta-casein by a two-state model or by the closed-association model, i.e., monomers if micelles.
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46
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Marchesseau S, Mani JC, Martineau P, Roquet F, Cuq JL, Pugnière M. Casein interactions studied by the surface plasmon resonance technique. J Dairy Sci 2002; 85:2711-21. [PMID: 12487438 DOI: 10.3168/jds.s0022-0302(02)74358-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Surface plasmon resonance technique was investigated for the first time to study the apparent hydrophobicity and association properties of the major bovine caseins: alpha(s)-(alpha(s1)- and alpha(s2)-caseins in a 4:1 proportion), beta-, and kappa-caseins. The apparent hydrophobicities of the caseins were evaluated by a new method based on the binding level of casein on a hydrophobic sensor chip, and kinetic and equilibrium affinity constants were determined for the following casein interactions: alpha(s)/alpha(s), alpha(s)/beta, alpha(s)/kappa, beta/beta, and beta/kappa, using a sensor chip modified with covalent immobilized caseins. The study by surface plasmon resonance technology of these casein interactions under different conditions (pH, ionic strength, calcium concentration, chemical modification) demonstrated that, at neutral pH, electrostatic repulsive forces play an important role since an increase in ionic strength of the medium resulted in a stronger interaction. When charge repulsions were reduced by either acidification, increase in ionic strength, or dephosphorylation, casein interactions were reinforced, presumably due to weak attractive forces. Moreover, in this molecular model, we showed that addition of calcium greatly increased the binding response between the most phosphorylated caseins and that the added calcium (2 mM) participated directly in the formation of bridges between the phosphate groups of the casein molecules.
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Affiliation(s)
- S Marchesseau
- Laboratoire de Génie Biologique et Sciences des Aliments, Université Montpellier II, 34095 Montpellier Cedex 5, France
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Secondary structural studies of bovine caseins: temperature dependence of β-casein structure as analyzed by circular dichroism and FTIR spectroscopy and correlation with micellization. Food Hydrocoll 2001. [DOI: 10.1016/s0268-005x(01)00080-7] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mauer LJ, Smith DE, Labuza TP. Effect of water content, temperature and storage on the glass transition, moisture sorption characteristics and stickiness of β‐casein1. INTERNATIONAL JOURNAL OF FOOD PROPERTIES 2000. [DOI: 10.1080/10942910009524630] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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