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Biochimica Et Biophysica Acta. Proteins... Nov 2022Protein misfolding and aggregation are associated with several human diseases such as Alzheimer's, Parkinson's, prion related disorders, type-II diabetes, etc. Different...
Protein misfolding and aggregation are associated with several human diseases such as Alzheimer's, Parkinson's, prion related disorders, type-II diabetes, etc. Different strategies using molecular chaperones, synthetic and naturally occurring small molecules, osmolytes, etc. have been used to prevent protein aggregation and amyloid fibril formation. In this study, we have used bovine α-lactalbumin at pH 1.6, 37 °C, and shaking conditions to promote amyloid fibril formation. Polyol and sugar osmolytes like glycerol, sorbitol, and trehalose have been used to inhibit the fibrillation of a number of proteins. In the present work, amyloid fibril formation of α-lactalbumin has been shown by ThT assay and AFM, while changes in the secondary structure during fibrillation has been followed by circular dichroism spectroscopy. Our results show that glycerol, sorbitol, and trehalose affect amyloid fibril formation of α-lactalbumin in a concentration-dependent manner. There is a delay in the lag phase of amyloid fibril formation in sorbitol and trehalose and complete inhibition in 6 M glycerol. Our results indicate that delay in the lag phase and inhibition of amyloid fibril formation are due to the stabilization of molten globule state by these osmolytes. At pH 1.6, the molten globule as well as the amyloid fibrils bind to ANS. However, when pH was shifted from 1.6 to 7, only the oligomeric and the fibrillar species bind to ANS due to refolding of molten globule state. The outcome of this study might be useful in designing small molecules which may stabilize the intermediate states, thus preventing amyloid fibril formation.
Topics: Amyloid; Animals; Cattle; Circular Dichroism; Glycerol; Humans; Lactalbumin; Molecular Chaperones; Polymers; Prions; Protein Aggregates; Protein Folding; Sorbitol; Sugars; Trehalose
PubMed: 36096464
DOI: 10.1016/j.bbapap.2022.140853 -
Journal of Agricultural and Food... May 2021This study analyzed the effect of lipid peroxidation using 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) and acrolein on the and allergenicity of α-lactalbumin...
This study analyzed the effect of lipid peroxidation using 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH) and acrolein on the and allergenicity of α-lactalbumin (α-La). The structure of oxidized α-La was evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis, fluorescence spectroscopy, and circular dichroism, whereas the changes in the allergenic properties were evaluated. Lipid peroxidation induced changes to the structural properties that might destroy and/or mask α-La epitopes. In comparison to native α-La, oxidation complexes caused a decrease in the immunoglobulin E (IgE) binding capacity, as observed via immunoblotting. Moreover, the capacity to release mediators and cytokines from KU812 cells was also greatly reduced. , oxidation with AAPH and acrolein caused a significant reduction in IgE, IgG, IgG1, mast cell protease 1, and plasma histamine, along with the reduction of mast surface c-Kit and FcεRI expression. Therefore, these results indicate that oxidation via AAPH and acrolein can potentially reduce the allergenicity of α-La, which can help with the better understanding of the changes in allergenicity of milk allergen by lipid peroxidation.
Topics: Allergens; Animals; Immunoglobulin E; Lactalbumin; Lipid Peroxidation; Milk
PubMed: 33974424
DOI: 10.1021/acs.jafc.1c00559 -
Molecules (Basel, Switzerland) Aug 2022In this study, high pressure processing (HPP) and thermal treatment were comparatively evaluated by examining their impacts on the binding behavior and interaction...
In this study, high pressure processing (HPP) and thermal treatment were comparatively evaluated by examining their impacts on the binding behavior and interaction between α-lactalbumin (α-La) and pelargonium-3-glucoside (P3G) under pH values of 6.0, 7.4, and 8.0. The methods of circular dichroism spectroscopy, fluorescence quenching, dynamic light scattering, and molecular simulation were used to characterize the effects of processing-induced changes in protein structure, size distribution, binding site conformation, and residue charges on their binding characteristics between them. The results indicated that the thermal treatments significantly increased the quenching constants of the complex at pH 7.4/8.0 and 60/80 °C, as well as the accessible fraction of protein at pH 8.0/80 °C. Both HPP and thermal treatments increased the random coil content and showed limited effects on the α-helix and β-sheet contents of α-La and caused the aggregation of the complex to varying degrees. Molecular dynamic simulation and docking analyses revealed that the binding site of the complex did not change under different processing conditions, but the solvent-accessible surface area varied under different conditions.
Topics: Circular Dichroism; Glucosides; Hydrogen-Ion Concentration; Lactalbumin; Pelargonium; Spectrometry, Fluorescence
PubMed: 35956895
DOI: 10.3390/molecules27154944 -
Biology of Sport Apr 2023This double-blind randomised placebo-controlled trial aimed to investigate the effects of α-lactalbumin consumption on sleep quality and quantity in female rugby union...
This double-blind randomised placebo-controlled trial aimed to investigate the effects of α-lactalbumin consumption on sleep quality and quantity in female rugby union athletes during a competition season. Eighteen semi-professional female rugby union players (age 23.8 ± 5.2 y; mean ± SD) wore wrist actigraphy watches for four seven-day blocks corresponding to the pre-season, a home game, a bye week (i.e. no competition game scheduled) and an away game. Participants consumed either an α-lactalbumin (α-LAC), or placebo drink (PLA) every night two hours before bed for the duration of the season. Generalised linear mixed models were used to investigate the effects of the nutritional intervention on sleep variables (total sleep time, sleep efficiency (SE), sleep onset latency (SOL) and wake after sleep onset) over the duration of the season. There was a significant condition by period interaction effect on SOL (p = 0.01). While similar at baseline (23.3 ± 16.3 and 23.2 ± 18.9 min α-LAC and placebo respectively) and for the home game (22.4 ± 17.6 and 19.3 ± 14.9 min α-LAC and placebo respectively), SOL was reduced in the α-LAC group for the bye (11.6 ± 13.4 min) and away game (17.0 ± 11.5 min; p = 0.045). In comparison, SOL remained unchanged in the PLA group (bye 21.2 ± 17.3 and away 22.5 ± 18.5 min). Pre-sleep α-lactalbumin consumption improved SOL in a semi-professional female team-sport cohort. Thus, α-lactalbumin could be utilised by athletes to support sleep during a competitive season.
PubMed: 37077794
DOI: 10.5114/biolsport.2023.116002 -
Food Chemistry: X Mar 2022Glycated protein is a kind of promising material that can improve the bioavailability of bioactive compounds and achieve sustained release under digestion. In this...
Glycated protein is a kind of promising material that can improve the bioavailability of bioactive compounds and achieve sustained release under digestion. In this study, the α-lactalbumin (ALA)-dextran conjugates synthesized by Maillard reaction were fabricated to load and protect quercetin. Quercetin-loaded micelles stabilized by the ALA-dextran conjugates 1:4 showed the smallest size (428.57 ± 5.64 nm) with highest encapsulation efficiency (94.38% ± 0.50%) of quercetin. Compared to ALA/dextran mixture complex, the conjugates-based micelles had better pH, ionic strength and photothermal stability. Furthermore, the micelles composed of the conjugates 1:2 and 1:4 showed the best controlled release effect during the simulated digestion, releasing 62.41% and 66.15% of quercetin from the total encapsulated contents, respectively, which was mainly related to the resistance of glycated ALA to the enzymes. The findings indicated that ALA-dextran conjugates could be effectively designed for the ideal delivery system of hydrophobic bioactive compounds in food industry.
PubMed: 35499028
DOI: 10.1016/j.fochx.2022.100257 -
Biochemical and Biophysical Research... Nov 2019This work focuses on the study of multimeric alpha-lactalbumin oleic acid and lactoferrin oleic acid complexes. The purpose of the research is to study possible...
This work focuses on the study of multimeric alpha-lactalbumin oleic acid and lactoferrin oleic acid complexes. The purpose of the research is to study possible mechanisms involved in their pro-apoptotic activities, as seen in some tumor cell cultures. Complexes featuring oleic acid (OA) with human alpha-lactalbumin (hAl) or with bovine alpha-lactalbumin (bAl), and human lactoferrin (hLf) were investigated using small-angle neutron scattering (SANS). It was shown that while alpha-lactalbumin protein complexes were formed on the surface of polydisperse OA micelles, the lactoferrin complexes comprised a monodisperse system of nanoscale particles. Both hAl and hLf complexes appeared to interact with the chromatin of isolated nuclei affecting chromatin structural organization. The possible roles of these processes in the specific anti-tumor activity of these complexes are discussed.
Topics: Animals; Antineoplastic Agents; Apoptosis; Cattle; Cell Nucleus; Chromatin; HeLa Cells; Humans; Lactalbumin; Lactoferrin; Micelles; Oleic Acid; Oleic Acids; Scattering, Small Angle
PubMed: 31582209
DOI: 10.1016/j.bbrc.2019.09.116 -
Journal of Photochemistry and... Aug 2020Since the high incidence of aflatoxin M1 (AFM1) in milk and dairy products poses a serious risk to human health, this work aimed to investigate the complex formation...
Since the high incidence of aflatoxin M1 (AFM1) in milk and dairy products poses a serious risk to human health, this work aimed to investigate the complex formation between bovine α-lactalbumin (α-La) and AFM1 using different spectroscopic methods coupled with molecular docking studies. Fluorescence spectroscopy measurements demonstrated the AFM1 addition considerably reduced the α-La fluorescence intensity through a static quenching mechanism. The results indicated on the endothermic character of the reaction, and the hydrophobic interaction played a major role in the binding between AFM1 and α-La. The binding site stoichiometric value (n = 1.32) and a binding constant of 2.12 × 10 M were calculated according to the Stern-Volmer equation. The thermodynamic parameters ΔH, ΔS and ΔG were determined at 93.58 kJ mol, 0.378 kJ mol K and -19.17 ± 0.96 kJ mol, respectively. In addition, far-UV circular dichroism studies revealed alterations in the α-La secondary structures when the α-La-AFM1 complex was formed. An increased content of the α-helix structures (from 35 to 40%) and the β-sheets (from 16 to 19%) were observed. Furthermore, protein-ligand docking modelling demonstrated AFM1 could bind to the hydrophobic regions of α-La protein. Overall, the gathered results confirmed the α-La-AFM1 complex formation.
Topics: Aflatoxin M1; Animals; Binding Sites; Cattle; Food Contamination; Humans; Hydrophobic and Hydrophilic Interactions; Lactalbumin; Ligands; Milk; Molecular Docking Simulation; Protein Structure, Secondary; Serum Albumin, Bovine; Thermodynamics
PubMed: 32682284
DOI: 10.1016/j.jphotobiol.2020.111957 -
Foods (Basel, Switzerland) Jan 2024Protein content variation in milk can impact the quality and consistency of dairy products, necessitating access to in-line real time monitoring. Here, we present a...
Protein content variation in milk can impact the quality and consistency of dairy products, necessitating access to in-line real time monitoring. Here, we present a chemometric approach for the qualitative and quantitative monitoring of β-lactoglobulin and α-lactalbumin, using mid-infrared spectroscopy (MIR). In this study, we employed Hotelling T2 and Q-residual for outlier detection, automated preprocessing using nippy, conducted wavenumber selection with genetic algorithms, and evaluated four chemometric models, including partial least squares, support vector regression (SVR), ridge, and logistic regression to accurately predict the concentrations of β-lactoglobulin and α-lactalbumin in milk. For the quantitative analysis of these two whey proteins, SVR performed the best to interpret protein concentration from 197 MIR spectra originating from 42 Cornell University samples of preserved pasteurized modified milk. The R values obtained for β-lactoglobulin and α-lactalbumin using leave one out cross-validation (LOOCV) are 92.8% and 92.7%, respectively, which is the highest correlation reported to date. Our approach introduced a combination of preprocessing automation, genetic algorithm-based wavenumber selection, and used Optuna to optimize the framework for tuning hyperparameters of the chemometric models, resulting in the best chemometric analysis of MIR data to quantitate β-lactoglobulin and α-lactalbumin to date.
PubMed: 38201194
DOI: 10.3390/foods13010166 -
Journal of the Science of Food and... Aug 2021α-lactalbumin (α-La) is of great interest to the industry as a result of its excellent functional properties and nutritional value. Aqueous two-phase flotation (ATPF)...
BACKGROUND
α-lactalbumin (α-La) is of great interest to the industry as a result of its excellent functional properties and nutritional value. Aqueous two-phase flotation (ATPF) of thermo-sensitive polymer poly (ethylene glycol-ran-propylene glycol) monobutyl ether (UCON) and KH PO was applied to directly separate and purify α-La from milk whey, which was purposed to simplify the production process and reduced cost of production.
RESULTS
The effect of ATPF composition and operating parameters on the flotation efficiency (E) and purity of α-La were investigated. The optimal conditions included 2 min of premixing time, 30 mL min flow velocity and 20 min of flotation time, whereas the composition conditions comprised 35.0 mL 0.18 g mL phosphate solution (containing 10% (cow milk whey/salt solution, v/v) cow milk whey, 50 ppm defoamer and 2 g NaCl) and 5.0 mL of 40% (w/w) UCON solution. Under the optimal conditions, E of α-La was 95.67 ± 1.04% and purity of α-La was 98.78 ± 1.19%. UCON was recovered by a thermally-induced phase separation and reused in next ATPF process without reducing E of α-La. Purified α-La was characterized by several key technologies. The results indicated that α-La in cow milk whey could be directly separated and purified by the ATPF and the purity was satisfactory. Moreover, it was suggested there was no obvious structure difference between the α-La separated by ATPF and the α-La standard.
CONCLUSION
The present study enabled the recycling of UCON, providing an effective, economically viable and environmentally friendly approach for the separation and purification of protein. © 2021 Society of Chemical Industry.
Topics: Animals; Cattle; Chemical Fractionation; Hot Temperature; Hydrogen-Ion Concentration; Lactalbumin; Phosphates; Polymers; Whey
PubMed: 33420726
DOI: 10.1002/jsfa.11055 -
Frontiers in Immunology 2022Camel milk (CM) has been found to have several health benefits, including antiviral, antibacterial, anti-tumor, anti-fungal, antioxidant, hypoglycaemic and anti-cancer... (Review)
Review
Camel milk (CM) has been found to have several health benefits, including antiviral, antibacterial, anti-tumor, anti-fungal, antioxidant, hypoglycaemic and anti-cancer activities. In addition, CM can counter signs of aging and may be a useful naturopathic treatment for autoimmune diseases. The composition of CM varies with geographic origin, feeding conditions, seasonal and physiological changes, genetics and camel health status. In the present review, we collate the diverse scientific literature studying antioxidant, anti-inflammatory and immunomodulatory effects of CM and its bioactive compounds. The databases Scopus, PubMed, and Web of Science were searched until the end of September 2021 using the keywords: camel milk, antioxidant, anti-inflammatory, immunomodulatory. The anti-inflammatory mechanism of CM in various inflammatory disorders was consistently reported to be through modulating inflammatory cells and mediators. The common anti-inflammatory bioactive components of CM seem to be lactoferrin. The antioxidant effects of α-lactalbumin, β-caseins and vitamin C of CM work by reducing or inhibiting the production of reactive oxygen species (ROS), hydroxyl radicals, nitric oxide (NO), superoxide anions and peroxyl radicals, likely alleviating oxidative stress. Higher levels of protective proteins such as lysozyme, IgG and secretory IgA compared to cow's milk, and insulin-like protein activity of CM on ß cells appear to be responsible for the immunomodulatory properties of CM. The evidence indicates that CM and its bioactive components has the potential to be a therapeutic value for diseases that are caused by inflammation, oxidative stress and/or immune-dysregulation.
Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Camelus; Cattle; Female; Immunomodulation; Milk
PubMed: 35493477
DOI: 10.3389/fimmu.2022.855342