α-Lactalbumin and sodium dodecyl sulfate aggregates: Denaturation, complex formation and time stability

Sun, Yang; Filho, Pedro Leonidas Oseliero; Oliveira, Cristiano L. P.

doi:10.1016/j.foodhyd.2016.07.031

Cited by 21 publications

(12 citation statements)

References 40 publications

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“…These studies indicate that complex formation is driven by electrostatic interactions as well as interactions between exposed hydrophobic patches on the unfolded protein and the surfactant micelles. Other studies of lysozyme (16,17), a-lactalbumin (18), and Acyl-CoAbinding protein (ACBP) (19) with SDS added in different proportions, highlight a variety of complex structures with increasing SDS concentration. At low SDS concentrations, the native ACBP binds a small number of SDS molecules, whereas intermediate SDS concentrations lead to a protein dimer formed around a shared micelle; finally, higher SDS concentrations lead to complexes with only one protein per micelle.…”

Section: Introductionmentioning

confidence: 99%

Myoglobin and α-Lactalbumin Form Smaller Complexes with the Biosurfactant Rhamnolipid Than with SDS

Mortensen

Madsen

Andersen

et al. 2017

Biophysical Journal

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Biosurfactants (BSs) attract increasing attention as sustainable alternatives to petroleum-derived surfactants. This necessitates structural insight into how BSs interact with proteins encountered by current chemical surfactants. Thus, small-angle x-ray scattering (SAXS) has been used for studying the structures of complexes made of the proteins α-Lactalbumin (αLA) and myoglobin (Mb) with the biosurfactant rhamnolipid (RL). For comparison, complexes between αLA and the chemical surfactant sodium dodecyl sulfate (SDS) were also investigated. The SAXS data for pure RL micelles can be described by prolate core-shell structures with a core radius of 7.7 Å and a shell thickness of 12 Å, giving an aggregation number of 11. The small core radius is attributed to RL's complex hydrophobic tail. Data for the αLA-RL complex agree with a 12-molecule micelle with a single protein molecule in the shell. For Mb-RL, the analysis gives complexes of two connected micelles, each containing 10 RL and one protein in the shells. αLA-RL and Mb-RL form surfactant-saturated complexes above 5.6 and 4.7 mM RL, respectively, leaving the remaining RL in free micelles. The SAXS data for SDS agree with oblate-shaped micelles with a core of 20 Å, core eccentricity 0.7, and shell thickness of 5.45 Å, with an aggregation number of 74. The αLA-SDS complexes contain a prolate micelle with a core radius of 11-14 Å and a shell of 8-12 Å with up to 3 αLA per particle and up to 43 SDS per αLA, both considerably larger than for RL. Unlike the RL-protein complexes, the number of surfactant molecules in αLA-SDS complexes increases with surfactant concentration, and saturate at higher surfactant concentrations than αLA-RL complexes. The results highlight how RL and SDS follow similar overall rules of self-assembly and interactions with proteins, but that differences in the strength of protein-surfactant interactions affect the formed structures.

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Section: Introductionmentioning

confidence: 99%

Myoglobin and α-Lactalbumin Form Smaller Complexes with the Biosurfactant Rhamnolipid Than with SDS

Mortensen

Madsen

Andersen

et al. 2017

Biophysical Journal

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“…The CAPITO analysis (Table 2) of the CD spectra shows a helical conformational stabilizing effect of polysorbate-20 on caprine β-casein. Hydrogen binding derived from hydroxyl groups of polysorbate-20 with amino acid residues of protein plays a key role in the formation of a hydrogen bond network for stabilizing the helical conformational change induced by surfactant, as previously observed in α-lactalbumin [33]. Figure 3 shows the mean residue ellipticity (θ) as a function of wavelength in the far-UV region for the caprine β-casein/polysorbate-20 complex at 25 • C. The CAPITO analysis (Table 2) of the CD spectra shows a helical conformational stabilizing effect of polysorbate-20 on caprine β-casein.…”

Section: Estimation Of Secondary Structure Of β-Casein/polysorbate-20 Complex In Solutionmentioning

confidence: 62%

“…Figure 3 shows the mean residue ellipticity (θ) as a function of wavelength in the far-UV region for the caprine β-casein/polysorbate-20 complex at 25 • C. The CAPITO analysis (Table 2) of the CD spectra shows a helical conformational stabilizing effect of polysorbate-20 on caprine β-casein. Hydrogen binding derived from hydroxyl groups of polysorbate-20 with amino acid residues of protein plays a key role in the formation of a hydrogen bond network for stabilizing the helical conformational change induced by surfactant, as previously observed in α-lactalbumin [33]. In the case of bovine β-casein, the secondary structure content showed 13.5% of α-helical, 17.9% of β-sheet, and 69.1% of irregular conformation (Table 2), indicating the intrinsically disordered structure of bovine β-casein [34].…”

Section: Estimation Of Secondary Structure Of β-Casein/polysorbate-20 Complex In Solutionmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 86%

“…The lauric acid chains of polysorbate-20 may be aligned along the α-helical and β-sheet structures in order to stabilize disordered regions and expose aromatic residues of bovine β-casein, thereby increasing the secondary structure of bovine β-casein [ 35 ]. The hydrophobic interactions and hydrogen bonds are the main factors governing the stabilization [ 33 , 34 , 36 ].…”

Section: Resultsmentioning

confidence: 99%

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Interface Compositions as Determinants of Resveratrol Stability in Nanoemulsion Delivery Systems

Mora-Gutierrez

Attaie

González

et al. 2020

Foods

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The incorporation of hydrophobic ingredients, such as resveratrol (a fat-soluble phytochemical), in nanoemulsions can increase the water solubility and stability of these hydrophobic ingredients. The nanodelivery of resveratrol can result in a marked improvement in the bioavailability of this health-promoting ingredient. The current study hypothesized that resveratrol can bind to caprine casein, which may result in the preservation of the biological properties of resveratrol. The fluorescence spectra provided proof of this complex formation by demonstrating that resveratrol binds to caprine casein in the vicinity of tryptophan amino acid residues. The caprine casein/resveratrol complex is stabilized by hydrophobic interactions and hydrogen bonds. Hence, to study the rate of resveratrol degradation during processing/storage, resveratrol losses were determined by reversed-phase high performance liquid chromatography (RP-HPLC) in nanoemulsions stabilized by bovine and caprine caseins individually and in combination with polysorbate-20. At 48 h oxidation, 88.33% and 89.08% was left of resveratrol in the nanoemulsions stabilized by caprine casein (αs1-I)/polysorbate-20 complex and caprine (αs1-II)/polysorbate-20 complex, while there was less resveratrol left in the nanoemulsions stabilized by bovine casein/polysorbate-20 complex, suggesting that oxygen degradation was involved. The findings of this study are crucial for the food industry since they imply the potential use of caprine casein/polysorbate-20 complex to preserve the biological properties of resveratrol.

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Advance Techniques in Biophysics

Fioramonte

Gozzo

Oliveira

et al. 2017

Introduction to Biomolecular Structure and Biophysics

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α-Lactalbumin and sodium dodecyl sulfate aggregates: Denaturation, complex formation and time stability

Cited by 21 publications

References 40 publications

Myoglobin and α-Lactalbumin Form Smaller Complexes with the Biosurfactant Rhamnolipid Than with SDS

Myoglobin and α-Lactalbumin Form Smaller Complexes with the Biosurfactant Rhamnolipid Than with SDS

Interface Compositions as Determinants of Resveratrol Stability in Nanoemulsion Delivery Systems

Advance Techniques in Biophysics

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