Water interactions with varying molecular states of bovine casein: 2H NMR relaxation studies

Kumosinski, Thomas F.; Pessen, Helmut; Prestrelski, Steven J.; Farrell, Harold M.

doi:10.1016/0003-9861(87)90565-0

Cited by 30 publications

(36 citation statements)

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“…The T 2 water proton relaxation in solutions containing 3 % whey proteins and 12 % sodium caseinate was slow (slightly more rapid than in 3 % whey proteins solution) while it was much faster in the presence of 3 % whey proteins and 12% casein micelles. This observation, previously reported (Kumosinski et al 1987;Farrell et al 1989), can be explained by the difference in structure between casein micelles (spherical particles with high amounts of interstitial water) and caseinate. At the same protein concentration (3% whey protein and 12% casein micelles) T 2 relaxation was even more rapid in dialysed skim milk, probably owing to the other constituents present in the milk.…”

Section: Discussionsupporting

confidence: 52%

Low-field nuclear magnetic resonance relaxation study of thermal effects on milk proteins

Lambelet¹,

Berrocal²,

Renevey³

1992

Journal of Dairy Research

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SUMMARY. A recently described nuclear magnetic resonance (NMR) method was evaluated for its usefulness in studying thermal effects on milk proteins. The increase in water proton T 2 relaxation rate observed during thermal treatment of aqueous whey protein solutions above the denaturing onset temperature paralleled results obtained with the standard Rowland (1938) method. The influence of milk constituents on NMR characteristics was analysed. The NMR response increased with the ionic strength and the addition of caseinate or casein micelles. The relevance of the T 2 relaxation probe for studying thermal modifications of milk proteins is discussed. It is proposed to apply the NMR method for determining either reversible or irreversible thermal denaturation of whey proteins in model systems.

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Section: Discussionsupporting

confidence: 52%

Low-field nuclear magnetic resonance relaxation study of thermal effects on milk proteins

Lambelet¹,

Berrocal²,

Renevey³

1992

Journal of Dairy Research

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“…1b). The submicelle hypothesis has been historically supported by biochemical and biophysical studies [39,40,42,57] on the individual casein components, reconstitution of micelles from their component caseins [27,41,56], as well as electron microscopy of the micelles themselves [8] and partially decomposed micelles. Early studies on the purified caseins demonstrated that in the absence of calcium they formed rather large aggregates (submicelles) and that these aggregates formed colloidal complexes in the presence of added calcium.…”

Section: The Submicelle Theory Of Casein Structurementioning

confidence: 99%

Studies of casein micelle structure: the past and the present

2007

Lait

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At the heart of the milk system are the colloidal casein-calcium-transport complexes termed the casein micelles. The application of physical chemical techniques such as light, neutron, and X-ray scattering, and Electron Microscopy (EM) has yielded a wealth of experimental detail concerning the structure of the casein micelle. From these experimental data bases have arisen two conflicting models for the internal structure of the casein micelle. One model emphasizes protein submicellar structures as the dominant feature, while the other proposes that inorganic calcium phosphate nanoclusters serve this function. In this study, these models are critically examined in light of the two current primary dogmas of structural biology which are: protein structure gives rise to function and that competent and productive protein-protein interactions (associations) will lead to efficient transit through the mammary secretory apparatus. In this light an overwhelming argument can be made for the formation of proteinaceous complexes (submicelles) as the formative agents in the synthesis of casein micelles in mammary tissue. Whether these submicelles persist in milk has been questioned. Recently we have carried out studies on casein micelles and submicelles using Atomic Force Microscopy (AFM) and high resolution Transmission Electron Microscopy (TEM) to gain insights on the nature of protein-protein interactions in submicelles and micelles from a structural biology perspective. The results provide experimental evidence that protein-protein interactions are important in the formation and stabilization of casein micelles. milk / micelle / casein / structure / protein-protein interaction

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“…The sign of the second virial coefficient B 0 may serve as an indication of the type of protein-protein interactions: B 0 is positive for repulsive effects and negative for attractive ones. The B 0 (mL/mg) virial coefficient reflects interactions related to the "net" protein charge Z, the protein excluded volume v j p (mL/mg), and a preferential interaction term ∂g s /∂g p (mg of bound salt/ mg of protein; Arakawa and Timasheff, 1982;Kumosinski et al, 1987):…”

Section: Resultsmentioning

confidence: 99%

“…At all three temper- a The protein concentration was in mg of protein/mL of solvent. b Deuterium NMR experiments at 30 °C yielded a value of 0.0032 (Kumosinski et al, 1987). a From oxygen-17 NMR data at 4, 21, and 37 °C and at pD 6.98, according to a two-state, isotropic model (Mora-Gutierrez et al, 1995).…”

Section: Resultsmentioning

confidence: 99%

“…Recently, there has been great interest in the hydration of milk proteins (Kneifel et al, 1991). Deuterium NMR studies were carried out on bovine casein micelles (Kumosinski et al, 1987;Farrell et al, 1989); however, the hydration of caprine casein micelles has not yet been investigated by NMR relaxation techniques. Because the oxygen nucleus is the best probe for studying water binding, molecular motions of water, and water-protein interactions in solution (Halle et al, 1981;Denisov and Halle, 1995), we intend to investigate the hydration properties of bovine and caprine casein micelles by oxygen-17 NMR relaxation measurements.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Hydration Behavior of Bovine and Caprine Caseins As Determined by Oxygen-17 Nuclear Magnetic Resonance: Temperature Dependence of Colloidal Stability

Mora-Gutierrez

Farrell

Kumosinski

1996

J. Agric. Food Chem.

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Oxygen-17 nuclear magnetic resonance (NMR) transverse relaxation rates for bovine and caprine casein micelles at various temperatures were analyzed by nonlinear regression analysis and a protein activity model. The dependence of the NMR transverse relaxation rates was markedly nonlinear due to interactions between protein molecules. Temperature dependences of the hydration parameters of the bovine and caprine casein micelles were in accordance with the hypothesis that hydrophobic interactions are the predominant forces responsible for the self-association of the caseins. Relaxation differences between reconstituted micelles of bovine and caprine caseins strongly suggest that important structural dissimilarities exist between these milk proteins that are due to differences in the ratios of R s1 -to β-casein. A higher degree of hydration, characteristic of a more open and looser structure, is observed for caprine casein micelles high in R s1 -casein at 21 and 37 °C. The observed hydration behavior of bovine casein micelles at all three temperatures is consistent with the hydration values determined previously by deuterium NMR studies of bovine casein micelles in D 2 O containing 1,4-piperazinediethanesulfonic acid. The correspondence between the deuterium and oxygen-17 results suggests that both experiments detect exchangeable water "trapped" within the casein micelles. The dependence of the second virial coefficient B 0 on temperature was different for bovine and caprine casein micelles, suggesting the importance of "net" electrostatic charges of these milk proteins in their interactions with calcium and water.

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Water interactions with varying molecular states of bovine casein: 2H NMR relaxation studies

Cited by 30 publications

References 24 publications

Low-field nuclear magnetic resonance relaxation study of thermal effects on milk proteins

Low-field nuclear magnetic resonance relaxation study of thermal effects on milk proteins

Studies of casein micelle structure: the past and the present

Comparison of Hydration Behavior of Bovine and Caprine Caseins As Determined by Oxygen-17 Nuclear Magnetic Resonance: Temperature Dependence of Colloidal Stability

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