Thermal unfolding of bovine β-lactoglobulin studied by UV spectroscopy and fluorescence quenching

Busti, Pablo; Gatti, Carlos A.; Delorenzi, Néstor J.

doi:10.1016/j.foodres.2004.11.007

Cited by 31 publications

(19 citation statements)

References 31 publications

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“…(1) No changes in the excess ultrasonic velocity were observed up to 50 • C. (2) At 50 • C the velocity started to decrease. This decrease can be related to the partial unfolding of the protein and transition to the liquid-like "molten globule" state, which is expected to occur above 50 • C [12,15,16]. (3) A sharp drop in the excess ultrasonic velocity is seen between 67 • C and 76 • C (approximately) for pH 7.5 and between 74 • C and 82 • C (approximately) for pH 6.0.…”

Section: Photon Correlation Spectroscopymentioning

confidence: 99%

“…It was previously reported that at approximately 50 • C β-lactoglobulin undergoes conformational modifications, loses some elements of the tertiary and secondary structures, and partially unfolds [12,15,16]. At temperatures around and above 65 • C, β-lactoglobulin was described as being in a "molten globule state" [12,15,16], defined as a compact state with native-like Size, nm Changes in ultrasonic velocity, m⋅s -1 Fig. 4 Illustration of typical changes in ultrasonic velocity, , and attenuation, , at 15.6 MHz caused by an increase of the size of protein particles at protein concentration 2 % calculated at 80 • C using the particle size software module "Psize289" of an HR-US 102 spectrometer.…”

Section: Partial Unfolding and Transition To "Molten Globule" Statementioning

confidence: 99%

“…β-Lactoglobulin, the major whey protein in bovine milk, has often served as a model protein for studying heat-induced aggregation and gelation phenomena of globular proteins and has been widely investigated in the past [4,[6][7][8][9][10][11][12][13][14][15][16][17]. At neutral pH and room temperature, native β-lactoglobulin exists as a stable noncovalent dimer [10,11].…”

mentioning

confidence: 99%

“…These conformational changes involve exposure of both the interior hydrophobic residues and the sulfhydryl group that become available for intermolecular interactions (cross-links) [13,14]. Above approximately 65 • C, the protein exists in the state which was classified by several authors [12,15,16] as a molten globule state. Hydrophobic interactions between the exposed groups promote aggregation of the protein molecules while still in the molten-globule state.…”

mentioning

confidence: 99%

“…A number of different analytical techniques, such as electron microscopy, atomic force microscopy, light scattering, differential scattering calorimetry (DSC), nuclear magnetic resonance (NMR), circular dichroism, electrophoresis, chromatography, rheometry, etc. has been employed in the past in the analysis of protein aggregation [4,9,12,16,20]. However, real-time assessment of the formation of protein aggregates and nano-assemblies is a difficult task for traditional analytical techniques, especially when information on both the size and the intrinsic properties of the aggregates is required in a broad range of temperatures and states (solution, suspension of protein nano-particles, and gel).…”

mentioning

confidence: 99%

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Real-Time Monitoring of Heat-Induced Aggregation of β-Lactoglobulin in Aqueous Solutions Using High-Resolution Ultrasonic Spectroscopy

Ochenduszko

Buckin

2010

Int J Thermophys

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High-resolution ultrasonic spectroscopy was applied for real-time monitoring of the heat-induced denaturation and aggregation processes in aqueous solutions of β-lactoglobulin. The temperature profiles for the ultrasonic velocity and attenuation in the frequency range from 4 MHz to 16 MHz were measured during heating and cooling cycles, 35 • C to 120 • C to 35 • C, with different heating and cooling rates. Two processes were identified in the heating profiles: transition to the molten globular state followed by formation of protein aggregates. Both processes are accompanied by a decrease in the ultrasonic velocity and an increase in compressibility. The ultrasonic attenuation did not show a significant change during the transition to the molten globule but increased significantly during aggregation. The diameter of the aggregates (calculated from ultrasonic attenuation) was of the order of 100 nm and depended on the pH and the heating rate. Variation of pH from 6.0 to 7.5 had a pronounced effect on the size of protein aggregates. Some effect of pH on the intrinsic properties of aggregates was also detected.

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Section: Photon Correlation Spectroscopymentioning

confidence: 99%

Section: Partial Unfolding and Transition To "Molten Globule" Statementioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Real-Time Monitoring of Heat-Induced Aggregation of β-Lactoglobulin in Aqueous Solutions Using High-Resolution Ultrasonic Spectroscopy

Ochenduszko

Buckin

2010

Int J Thermophys

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Effects of preheating temperatures on β‐lactoglobulin structure and binding interaction with dihydromyricetin

Zhang

Guan

Huang

et al. 2022

eFood

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Low aqueous solubility limits the bioactivity and bioaccessibility of dihydromyricetin (DHM). Preheating treatment affects the loading efficiency of β-lactoglobulin (β-Lg) to polyphenols, but the mechanism remained unclear. In this study, a serial of temperatures (298 K, 318 K, 338 K, 358 K, and 373 K) were set to analyze the preheating effects on the loading efficiency of β-Lg to DHM, and secondary structure change, binding interactions, and particle size distribution were measured and compared with discover the effects. β-Lg preheated at 358 K possessed the highest binding percentage of 0.45, higher than 0.27, 0.30, 0.36, and 0.40 at 298 K, 318 K, 338 K, and 373 K, the exposure of inside hydrophobic residues contribute the hydrophobic interaction with DHM. Fluorescence quenching and molecular docking analysis showed that DHM tend to bind to β-Lg preheated at 358 K with a binding constant of 1.76 × 10 5 L mol −1 and a binding score of −5.84 kcal mol −1 , higher than that of other temperatures. Particle size distribution showed that Z-average size at 358 K was 16.34 nm, significantly higher than others of 7.64, 8.06, 6.84, and 13.4 nm. Preheating unfolded the structure of β-Lg, exposing the internal residues and enhancing the interaction with DHM.

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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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Thermal unfolding of bovine β-lactoglobulin studied by UV spectroscopy and fluorescence quenching

Cited by 31 publications

References 31 publications

Real-Time Monitoring of Heat-Induced Aggregation of β-Lactoglobulin in Aqueous Solutions Using High-Resolution Ultrasonic Spectroscopy

Real-Time Monitoring of Heat-Induced Aggregation of β-Lactoglobulin in Aqueous Solutions Using High-Resolution Ultrasonic Spectroscopy

Effects of preheating temperatures on β‐lactoglobulin structure and binding interaction with dihydromyricetin

Low‐field NMR: A tool for studying protein aggregation

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