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Bayrak M, Mata J, Conn C, Floury J, Logan A. Application of small angle scattering (SAS) in structural characterisation of casein and casein-based products during digestion. Food Res Int 2023; 169:112810. [PMID: 37254386 DOI: 10.1016/j.foodres.2023.112810] [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: 12/22/2022] [Revised: 03/01/2023] [Accepted: 04/11/2023] [Indexed: 06/01/2023]
Abstract
In recent years, small and ultra-small angle scattering techniques, collectively known as small angle scattering (SAS) have been used to study various food structures during the digestion process. These techniques play an important role in structural characterisation due to the non-destructive nature (especially when using neutrons), various in situ capabilities and a large length scale (of 1 nm to ∼20 μm) they cover. The application of these techniques in the structural characterisation of dairy products has expanded significantly in recent years. Casein, a major dairy protein, forms the basis of a wide range of gel structures at different length scales. These gel structures have been extensively researched utilising scattering techniques to obtain structural information at the nano and micron scale that complements electron and confocal microscopy. Especially, neutrons have provided opportunity to study these gels in their natural environment by using various in situ options. One such example is understanding changes in casein gel structures during digestion in the gastrointestinal tract, which is essential for designing personalised food structures for a wide range of food-related diseases and improve health outcomes. In this review, we present an overview of casein gels investigated using small angle and ultra-small angle scattering techniques. We also reviewed their digestion using newly built setups recently employed in various research. To gain a greater understanding of micro and nano-scale structural changes during digestion, such as the effect of digestive juices and mechanical breakdown on structure, new setups for semi-solid food materials are needed to be optimised.
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Affiliation(s)
- Meltem Bayrak
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, Victoria 3030, Australia; School of Science, College of Science, Engineering and Health, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia.
| | - Jitendra Mata
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
| | - Charlotte Conn
- School of Science, College of Science, Engineering and Health, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia.
| | | | - Amy Logan
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, Victoria 3030, Australia.
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2
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Bayrak M, Mata J, Raynes JK, Greaves M, White J, Conn CE, Floury J, Logan A. Investigating casein gel structure during gastric digestion using ultra-small and small-angle neutron scattering. J Colloid Interface Sci 2021; 594:561-574. [PMID: 33780761 DOI: 10.1016/j.jcis.2021.03.087] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 02/24/2021] [Accepted: 03/15/2021] [Indexed: 11/25/2022]
Abstract
This study aimed to understand the structural devolution of 10% w/w rennet-induced (RG) and transglutaminase-induced acid (TG) gels in H2O and D2O under in vitro gastric conditions with and without pepsin. The real-time devolution of structure at a nano- (e.g. colloidal calcium phosphate (CCP) and micelle) and micro- (gel network) level was determined using ultra-small (USANS) and small-angle neutron scattering (SANS) with electron microscopy. Results demonstrate that gel firmness or elasticity determines disintegration behaviour during simulated mastication and consequently the particle size entering the stomach. Shear of mixing in the stomach, pH, and enzyme activity will also affect the digestion process. Our results suggest that shear of mixing primarily results in erosion at the particle surface and governs gel disintegration behaviour during the early stages of digestion. Pepsin diffusivity, and hence action, occur more readily in the latter stages of gastric digestion via access to the particle interior. This occurs via the progressively larger pores of the looser gel network and channels created within the larger, less dense casein micelles of the RG gels. Gel firmness and brittleness were greater in the D2O samples compared to H2O, facilitating gel disintegration. Despite the higher strength and elasticity of RG compared to TG, the protein network strands of the RG gels become more compact when exposed to the acidic gastric environment with comparatively larger pores observed through SEM imaging. This led to a higher degree of digestibility in RG gels compared to TG gels. This is the first study to examine casein gel structure during simulated gastric digestion using scattering and highlights the benefits of neutron scattering to monitor structural changes during digestion at multiple length scales.
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Affiliation(s)
- Meltem Bayrak
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, Victoria 3030, Australia; School of Science, STEM College, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia.
| | - Jitendra Mata
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
| | - Jared K Raynes
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, Victoria 3030, Australia.
| | - Mark Greaves
- CSIRO Manufacturing, Bayview Avenue, Clayton, VIC 3168, Australia.
| | - Jacinta White
- CSIRO Manufacturing, Bayview Avenue, Clayton, VIC 3168, Australia.
| | - Charlotte E Conn
- School of Science, STEM College, RMIT University, 124 La Trobe Street, Melbourne, VIC 3000, Australia.
| | | | - Amy Logan
- CSIRO Agriculture and Food, 671 Sneydes Road, Werribee, Victoria 3030, Australia.
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3
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McAulay K, Wang H, Fuentes-Caparrós AM, Thomson L, Khunti N, Cowieson N, Cui H, Seddon A, Adams DJ. Isotopic Control over Self-Assembly in Supramolecular Gels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:8626-8631. [PMID: 32614592 PMCID: PMC7467762 DOI: 10.1021/acs.langmuir.0c01552] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
It is common to switch between H2O and D2O when examining peptide-based systems, with the assumption being that there are no effects from this change. Here, we describe the effect of changing from H2O to D2O in a number of low-molecular-weight dipeptide-based gels. Gels are formed by decreasing the pH. In most cases, there is little difference in the structures formed at high pH, but this is not universally true. On lowering the pH, the kinetics of gelation are affected and, in some cases, the structures underpinning the gel network are different. Where there are differences in the self-assembled structures, the resulting gel properties are different. We, therefore, show that isotopic control over gel properties is possible.
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Affiliation(s)
- Kate McAulay
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Han Wang
- Department of Chemical and Biomolecular Engineering,
Whiting School of Engineering, Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | | | - Lisa Thomson
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
| | - Nikul Khunti
- Diamond Light Source Ltd., Harwell Science
and Innovation Campus, Didcot OX11 0QX, U.K.
| | - Nathan Cowieson
- Diamond Light Source Ltd., Harwell Science
and Innovation Campus, Didcot OX11 0QX, U.K.
| | - Honggang Cui
- Department of Chemical and Biomolecular Engineering,
Whiting School of Engineering, Johns Hopkins
University, 3400 North Charles Street, Baltimore, Maryland 21218, United States
| | - Annela Seddon
- School
of Physics, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K.
- Bristol Centre for
Functional Nanomaterials, HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, U.K.
| | - Dave J. Adams
- School of Chemistry, University of Glasgow, Glasgow G12 8QQ, U.K.
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Johansen NT, Pedersen MC, Porcar L, Martel A, Arleth L. Introducing SEC–SANS for studies of complex self-organized biological systems. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2018; 74:1178-1191. [DOI: 10.1107/s2059798318007180] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/14/2018] [Indexed: 01/11/2023]
Abstract
Small-angle neutron scattering (SANS) is maturing as a method for studying complex biological structures. Owing to the intrinsic ability of the technique to discern between 1H- and 2H-labelled particles, it is especially useful for contrast-variation studies of biological systems containing multiple components. SANS is complementary to small-angle X-ray scattering (SAXS), in which similar contrast variation is not easily performed but in which data with superior counting statistics are more easily obtained. Obtaining small-angle scattering (SAS) data on monodisperse complex biological structures is often challenging owing to sample degradation and/or aggregation. This problem is enhanced in the D2O-based buffers that are typically used in SANS. In SAXS, such problems are solved using an online size-exclusion chromatography (SEC) setup. In the present work, the feasibility of SEC–SANS was investigated using a series of complex and difficult samples of membrane proteins embedded in nanodisc particles that consist of both phospholipid and protein components. It is demonstrated that SEC–SANS provides data of sufficient signal-to-noise ratio for these systems, while at the same time circumventing aggregation. By combining SEC–SANS and SEC–SAXS data, an optimized basis for refining structural models of the investigated structures is obtained.
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Dutta B, Vos BE, Rezus YLA, Koenderink GH, Bakker HJ. Observation of Ultrafast Vibrational Energy Transfer in Fibrinogen and Fibrin Fibers. J Phys Chem B 2018; 122:5870-5876. [PMID: 29709181 PMCID: PMC5995459 DOI: 10.1021/acs.jpcb.8b03490] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
We
study the secondary structure of the blood protein fibrinogen
using two-dimensional infrared spectroscopy. With this technique,
we identify the amide I′ vibrational modes of the antiparallel
β-sheets and turns of fibrinogen. We observe ultrafast energy
flow among these amide I′ vibrational modes with a time constant
of ∼7 ps. This energy transfer time constant does not change
significantly upon fibrin fiber formation, indicating that the secondary
structure of the fibrinogen monomers remains largely unchanged in
the polymerization process.
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Affiliation(s)
| | | | - Yves L A Rezus
- Hogeschool Inholland , 1081 HV Amsterdam , The Netherlands
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Wufsus AR, Rana K, Brown A, Dorgan JR, Liberatore MW, Neeves KB. Elastic behavior and platelet retraction in low- and high-density fibrin gels. Biophys J 2015; 108:173-83. [PMID: 25564864 DOI: 10.1016/j.bpj.2014.11.007] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 10/06/2014] [Accepted: 11/06/2014] [Indexed: 11/30/2022] Open
Abstract
Fibrin is a biopolymer that gives thrombi the mechanical strength to withstand the forces imparted on them by blood flow. Importantly, fibrin is highly extensible, but strain hardens at low deformation rates. The density of fibrin in clots, especially arterial clots, is higher than that in gels made at plasma concentrations of fibrinogen (3-10 mg/mL), where most rheology studies have been conducted. Our objective in this study was to measure and characterize the elastic regimes of low (3-10 mg/mL) and high (30-100 mg/mL) density fibrin gels using shear and extensional rheology. Confocal microscopy of the gels shows that fiber density increases with fibrinogen concentration. At low strains, fibrin gels act as thermal networks independent of fibrinogen concentration. Within the low-strain regime, one can predict the mesh size of fibrin gels by the elastic modulus using semiflexible polymer theory. Significantly, this provides a link between gel mechanics and interstitial fluid flow. At moderate strains, we find that low-density fibrin gels act as nonaffine mechanical networks and transition to affine mechanical networks with increasing strains within the moderate regime, whereas high-density fibrin gels only act as affine mechanical networks. At high strains, the backbone of individual fibrin fibers stretches for all fibrin gels. Platelets can retract low-density gels by >80% of their initial volumes, but retraction is attenuated in high-density fibrin gels and with decreasing platelet density. Taken together, these results show that the nature of fibrin deformation is a strong function of fibrin fiber density, which has ramifications for the growth, embolization, and lysis of thrombi.
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Affiliation(s)
- Adam R Wufsus
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
| | - Kuldeepsinh Rana
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
| | - Andrea Brown
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
| | - John R Dorgan
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
| | - Matthew W Liberatore
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado
| | - Keith B Neeves
- Department of Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado; Department of Pediatrics, University of Colorado, Aurora, Colorado.
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Oppel C, Prévost S, Noirez L, Gradzielski M. The use of highly ordered vesicle gels as template for the formation of silica gels. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:8885-8897. [PMID: 21692463 DOI: 10.1021/la104972r] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
A spontaneously forming gel of unilamellar vesicles based on sodium oleate (Na oleate) and 1-octanol as amphiphiles has been employed as a template in the formation of a silica gel formed by the hydrolysis of the inorganic precursor tetraethyl orthosilicate (TEOS). Up to about 10 wt % TEOS can be incorporated into this vesicle gel without phase separation and in a fully homogeneous formation process by simple mixing of the components. The process itself relies solely upon the self-organizing properties of this amphiphilic template system. The formation process was followed by means of time-resolved turbidity, rheology, and small-angle neutron scattering (SANS) experiments. It can be concluded that the presence of the precursor TEOS affects the kinetics of the process but the original vesicle gel structure is retained even up to highest TEOS content. The kinetic studies confirm that under the chosen conditions the vesicle formation proceeds much faster than the hydrolysis of TEOS and the subsequent formation of the silica gel. SANS displays in the low q-range an additional scattering due to the silica gel network, i.e., a hybrid material of an amphiphilic vesicle gel and an inorganic oxide gel is formed. Thus, this method is a very facile novel route of forming a highly ordered silica/vesicle gel by employing a self-organizing amphiphilic system as template and the formation of the silica network proceeds in a fully homogeneous fashion under kinetic control.
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Affiliation(s)
- Claudia Oppel
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Berlin, Germany.
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Douarche C, Sikorav JL, Goldar A. Aggregation and adsorption at the air-water interface of bacteriophage phiX174 single-stranded DNA. Biophys J 2007; 94:134-46. [PMID: 17766344 PMCID: PMC2134866 DOI: 10.1529/biophysj.107.107771] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We study the phase behavior of phage phiX174 single-stranded DNA in very dilute solutions in the presence of monovalent and multivalent salts, in both water (H(2)O) and heavy water (D(2)O). DNA solubility depends on the nature of the salts, their concentrations, and the nature of the solvent. The appearance of attractive interactions between the monomers of the DNA chains in the bulk of the solution is correlated with an adsorption of the chains at the air-water interface. We characterize this correlation in two types of aggregation processes: the condensation of DNA induced by the trivalent cation spermidine and its salting out in the presence of high concentrations (molar and above) of monovalent (sodium) cations, both in water and in heavy water. The overall solubility of single-stranded DNA is decreased in D(2)O compared to H(2)O, pointing to a role of DNA hydration in addition to electrostatic factors in the observed phase separations. DNA adsorption involves attractive van der Waals forces, and these forces are also operating in the bulk aggregation process.
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Affiliation(s)
- C Douarche
- Physique de la Matière Condensée, Ecole Polytechnique, Centre National de la Recherche Scientifique, Palaiseau, France
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9
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Zhang D, Kovach IM. Full and partial deuterium solvent isotope effect studies of alpha-thrombin-catalyzed reactions of natural substrates. J Am Chem Soc 2005; 127:3760-6. [PMID: 15771510 DOI: 10.1021/ja043258o] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton inventory studies of the thrombin-catalyzed fibrinogen activation to fibrinopeptide A are most consistent with a two-proton bridge forming at the transition state probably between Ser195 OgammaH and His57 Nepsilon2 and His57 Ndelta1 and Asp102 COObeta- at the active site, with fractionation factors 0.66 +/- 0.03 under enzyme saturation with substrate and 0.64 +/- 0.03 at fibrinogen concentration at 0.2 Km, at pH 8.0, pD 8.6, and 25.0 +/- 0.1 degrees C. Strongly inverse solvent isotope effects (SIEs) result from inverse lag times and maximal slopes of blood clotting plots, which are also anion and cation dependent. The blood clot is much coarser in D2O, as indicated in clotting curves with 3-9 times shorter lag time and steeper slopes with respect to H2O. The finer the particles, the weaker the H-bonds interlocking the fibrin mesh and/or in water structure around fibrin. Proton inventories of inverse lag times and maximal slopes of blood clotting curves in buffers containing Na+ and Cl- ions give the best fit to an exponential dependence on deuterium content in the buffer and give fractionation factors 5.6 +/- 0.5 and 7.8 +/- 0.6 at pH 8.0 and 25.0 +/- 0.1 degrees C. The thrombin-catalyzed activation of protein C (PC) to APC is associated with inverse kinetic SIEs (KSIEs) of 0.75 +/- 0.09 and 1.02 +/- 0.06 in 0.3 M NaCl and 0.3 M choline chloride, respectively, at substrate concentrations = 0.2 Km. In comparison, thrombin-catalyzed hydrolysis of chromogenic substrates gives greater KSIEs (Enyedy, E. I.; Kovach. I. M J. Am. Chem. Soc. 2004, 126, 6017-6024) and more complex proton inventories than the ones reported here for the first time for natural substrates. The present study illuminates differences in the character of the rate-determining transition state for the initial phase of the two physiological reactions catalyzed by thrombin.
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Affiliation(s)
- Daoning Zhang
- Chemistry Department, The Catholic University of America, Washington, DC 20064, USA
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Sackett DL, Chernomordik V, Krueger S, Nossal R. Use of small-angle neutron scattering to study tubulin polymers. Biomacromolecules 2003; 4:461-7. [PMID: 12625746 DOI: 10.1021/bm025760b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Small-angle neutron scattering has been used to examine taxol-stabilized microtubules and other tubulin samples in both H(2)O and D(2)O buffers. Measurements were made at pH/pD values between 6.0 and 7.8, and observed scattered intensities, I(Q), have been interpreted in terms of multicomponent models of microtubules and related tubulin polymers. A semiquantitative curve fitting procedure has been used to estimate the relative amounts of the supramolecular components of the samples. At both pH and pD 7.0 and above, the tubulin polymers are seen to be predominantly microtubules. Although in H(2)O buffer the polymer distribution is little changed as the pH varies, when pD is lowered the samples appear to contain an appreciable amount of sheetlike structures and the average microtubule protofilament number increases from ca. 12.5 at pD > or = approximately 7.0 to ca. 14 at pD approximately 6.0. Such structural change indicates that analysis of microtubule solutions based on H(2)O/D(2)O contrast variation must be performed with caution, especially at lower pH/pD.
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Affiliation(s)
- Dan L Sackett
- Laboratory of Integrative and Medical Biophysics, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA
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