Low resolution NMR spectroscopy: a tool to study protein denaturation: I. Application to diamagnetic whey proteins

Lambelet, Pierre; Berrocal, Rafael; Ducret, F.

doi:10.1017/s0022029900026431

Cited by 32 publications

(38 citation statements)

References 27 publications

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“…This has already been reported for most of the protein-water systems studied (Oakes, 1976a,b;Lelihvre and Creamer, 1978;Mahdi, 1979;Richardson et al, 1986;Lambelet et al, 1989;Myers-Betts and Baianu, 1990a) and is consistent with a fast exchange between bound and free water populations (Derbyshire, 1982).…”

Section: Resultssupporting

confidence: 80%

“…The variation in transverse relaxation rates observed during heating conalbumin solution can therefore be associated with changes in the conformation of the protein. An increase in transverse relaxation rates has already been observed following thermal treatments of various proteins such as whey and egg white proteins (Oakes, 197613;Lambelet et al, 1988Lambelet et al, , 1989. In the case of bovine serum albumin (BSA), it was shown that on thermal denaturation the protein proton transverse relaxation rates become much higher, but the longitudinal relaxation rates remain unchanged (Oakes, 1976b).…”

Section: Protein C O N C E N T R a T I O N (W/w)mentioning

confidence: 99%

“…Thermal denaturation of proteins has thus been investigated by monitoring the longitudinal (2' 1) or the transverse (2'2) relaxation times during the heating (Goldsmith and Toledo, 1985;Rydzy and Skzynski, 1980;Blicharska and Rydzy, 1979;Pumpernik et al, 1975). However, since relaxation times are temperature dependent, we have developed a method for the study of protein denaturation in which the measurements are always carried out a t the same temperature (Lambelet et al, 1989). A decrease in water proton T2 relaxation time was observed after heating of diamagnetic whey protein aqueous solution.…”

Section: Introductionmentioning

confidence: 99%

“…A decrease in water proton T2 relaxation time was observed after heating of diamagnetic whey protein aqueous solution. This variation in NMR relaxation parameter could be associated with protein unfolding during denaturation (Lambelet et al, 1989). Introducing a paramagnetic ion into a sample drastically modifies the NMR relaxation parameters measured in this sample.…”

Section: Introductionmentioning

confidence: 99%

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Low-field nuclear magnetic resonance relaxation study of the thermal denaturation of transferrins

Lambelet¹,

Ducret²,

Leuba³

et al. 1991

J. Agric. Food Chem.

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The NMR method previously described by Lambelet et al. (J. Dairy Res. 1989,56,211-222) has been evaluated for the investigation of thermal and acid denaturation of transferrins in aqueous solution.Heating an apoovotransferrin or an apolactoferrin solution resulted in a slight increase in T1-l and an important increase in T2-1 relaxation rates within the denaturation range. The same treatment applied to corresponding iron-saturated proteins resulted in a decrease in these parameters due to modifications of the metal-protein complex accompanying the denaturation. It is proposed that these changes in NMR relaxation parameters can be used to monitor thermal denaturation of transferrins. Acid treatment led to a decrease in relaxation parameters for both apoovotransferrin and iron-saturated (down to pH 4) ovotransferrin. These variations in NMR parameters were related to protein denaturation and indicated that the protein modifications due to acid treatment were different from those occurring during heating.

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Section: Resultssupporting

confidence: 80%

Section: Protein C O N C E N T R a T I O N (W/w)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Low-field nuclear magnetic resonance relaxation study of the thermal denaturation of transferrins

Lambelet¹,

Ducret²,

Leuba³

et al. 1991

J. Agric. Food Chem.

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“…The increased water proton relaxation rate induced by aggregation could be explained by the simple molecular processes of diffusion and chemical exchange (Hills et al (27,28) and Lambelet et al (38)). The main effect of aggregation is to reduce the protein proton transverse relaxation time because the dipole-dipole interactions between the protein protons are no longer as efficiently averaged by rotational motion.…”

Section: Resultsmentioning

confidence: 99%

NMR Relaxation and Water Self-Diffusion Studies in Whey Protein Solutions and Gels

Colsenet¹,

Mariette²,

Cambert³

2005

J. Agric. Food Chem.

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The changes in water proton transverse relaxation behavior induced by aggregation of whey proteins are explained in terms of the simple molecular processes of diffusion and chemical exchange. The water self-diffusion coefficient was measured in whey protein solutions and gels by the pulsed field gradient NMR method. As expected, water self-diffusion was reduced with increased protein concentrations. Whatever the concentration, the water molecules were free to diffuse over distances varying from 15 to 47 mum. Water diffusion was constant over these distances, demonstrating that no restrictions were found to explain the water hindrance. The modification in protein structure by gelation induced a decrease in water diffusion. The effects of protein concentration on water diffusion are discussed and modeled. Two approaches were compared, the obstruction effect induced by a spherical particle and the cell model, which considered two water compartments with specific self-diffusion coefficients.

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Low‐field NMR: A tool for studying protein aggregation

2007

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Low-field nuclear magnetic resonance (NMR) spin-spin relaxation (T 2 ) measurements were used to study the denaturation and aggregation of β-lactoglobulin (β-LG) solutions of varying concentrations (1-80 g L −1 ) as they were heated at temperatures ranging from ambient up to 90• C. For concentrations of 1-10 g L −1 , the T 2 of β-LG solutions did not change, even after heating to 90• C. A decrease in T 2 was only observed when solutions having higher concentrations (20-80 g L −1 ) were heated. Circular dichroism (CD) spectroscopy and fluorescence tests using the dye 1-anilino-8-naphthalene sulfonate (ANS) on 0.2 and 1 g L −1 solutions, respectively, indicated there were changes in the protein's secondary and tertiary conformations when the β-LG solutions reached 70• C and above. In addition, dynamic light scattering (DLS) showed that protein aggregation occurred only at concentrations above 10 g L −1 and for heating at 70 • C and above. The hydrodynamic radius increased as T 2 decreased. When excess 2-mercaptoethanol was added, the changes in both T 2 and the hydrodynamic radius followed the same trend for all β-LG protein concentrations between 1 and 40 g L −1 . These observations led to the conclusion that the changes in T 2 were due to protein aggregation, not protein unfolding.

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Low resolution NMR spectroscopy: a tool to study protein denaturation: I. Application to diamagnetic whey proteins

Cited by 32 publications

References 27 publications

Low-field nuclear magnetic resonance relaxation study of the thermal denaturation of transferrins

Low-field nuclear magnetic resonance relaxation study of the thermal denaturation of transferrins

NMR Relaxation and Water Self-Diffusion Studies in Whey Protein Solutions and Gels

Low‐field NMR: A tool for studying protein aggregation

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