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Biomolecules Aug 2020α-Lactalbumin (α-LA) is a small (Mr 14,200), acidic (pI 4-5), Ca-binding protein. α-LA is a regulatory component of lactose synthase enzyme system functioning in the... (Review)
Review
α-Lactalbumin (α-LA) is a small (Mr 14,200), acidic (pI 4-5), Ca-binding protein. α-LA is a regulatory component of lactose synthase enzyme system functioning in the lactating mammary gland. The protein possesses a single strong Ca-binding site, which can also bind Mg, Mn, Na, K, and some other metal cations. It contains several distinct Zn-binding sites. Physical properties of α-LA strongly depend on the occupation of its metal binding sites by metal ions. In the absence of bound metal ions, α-LA is in the molten globule-like state. The binding of metal ions, and especially of Ca, increases stability of α-LA against the action of heat, various denaturing agents and proteases, while the binding of Zn to the Ca-loaded protein decreases its stability and causes its aggregation. At pH 2, the protein is in the classical molten globule state. α-LA can associate with membranes at neutral or slightly acidic pH at physiological temperatures. Depending on external conditions, α-LA can form amyloid fibrils, amorphous aggregates, nanoparticles, and nanotubes. Some of these aggregated states of α-LA can be used in practical applications such as drug delivery to tissues and organs. α-LA and some of its fragments possess bactericidal and antiviral activities. Complexes of partially unfolded α-LA with oleic acid are cytotoxic to various tumor and bacterial cells. α-LA in the cytotoxic complexes plays a role of a delivery carrier of cytotoxic fatty acid molecules into tumor and bacterial cells across the cell membrane. Perhaps in the future the complexes of α-LA with oleic acid will be used for development of new anti-cancer drugs.
Topics: Animals; Antineoplastic Agents; Humans; Hydrogen-Ion Concentration; Lactalbumin; Neoplasms; Oleic Acid
PubMed: 32825311
DOI: 10.3390/biom10091210 -
Nutrients Aug 2020Disturbed sleep may negatively influence physical health, cognitive performance, metabolism, and general wellbeing. Nutritional interventions represent a potential... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Disturbed sleep may negatively influence physical health, cognitive performance, metabolism, and general wellbeing. Nutritional interventions represent a potential non-pharmacological means to increase sleep quality and quantity.
OBJECTIVE
(1) Identify an optimal suite of nutritional ingredients and (2) validate the effects of this suite utilising polysomnography, and cognitive and balance tests.
METHODS
The optimal and least optimal combinations of six ingredients were identified utilising 55 male participants and a Box-Behnken predictive model. To validate the model, 18 healthy, male, normal sleepers underwent three trials in a randomised, counterbalanced design: (1) optimal drink, (2) least optimal drink, or (3) placebo were provided before bed in a double-blinded manner. Polysomnography was utilised to measure sleep architecture. Cognitive performance, postural sway, and subjective sleep quality, were assessed 30 min after waking.
RESULTS
The optimal drink resulted in a significantly shorter sleep onset latency (9.9 ± 12.3 min) when compared to both the least optimal drink (26.1 ± 37.4 min) and the placebo drink (19.6 ± 32.0 min). No other measures of sleep, cognitive performance, postural sway, and subjective sleep quality were different between trials.
CONCLUSION
A combination of ingredients, optimised to enhance sleep, significantly reduced sleep onset latency. No detrimental effects on sleep architecture, subjective sleep quality or next day performance were observed.
Topics: Adenosine Monophosphate; Adult; Dietary Supplements; Double-Blind Method; Fruit and Vegetable Juices; Glutamates; Humans; Lactalbumin; Male; Polysomnography; Prunus avium; Sleep; Tryptophan; Valerian
PubMed: 32854375
DOI: 10.3390/nu12092579 -
Journal of the Science of Food and... Jun 2023Ultrasound-assisted glycation is a promising method for decreasing the allergenicity of α-lactalbumin (ALA). However, there is a lack of in vivo studies on the...
BACKGROUND
Ultrasound-assisted glycation is a promising method for decreasing the allergenicity of α-lactalbumin (ALA). However, there is a lack of in vivo studies on the allergenicity of ultrasound-assisted glycated ALA. In this study, the effects of the ultrasound-assisted glycation of ALA on the allergenicity and intestinal microflora were characterized using a BALB/c mouse model.
RESULTS
Increased immunoglobulin -G/ immunoglobulin-E (IgG/IgE) and interleukin-4/6 (IL-4/6) secretions, and reduced interferon-γ (IFN-γ) secretions were found in the serum of ALA sensitized and challenged, mice in comparison with a control group. However, there was no significant difference between the mice fed with ultrasound-assisted glycated ALA and the control group. Mice that were sensitized and challenged with ALA showed disrupted intestinal microflora, manifesting in significantly decreased Firmicutes and significantly increased Proteobacteria. It was found that 100ALA-gal could maintain the intestinal microflora of mice in a normal state. Pearson's rank correlation showed that Proteobacteria and Spirochaetota were correlated positively with the IL-4/IL-6 level and were correlated negatively with the expression of IFN-γ. Proteobacteria were also significantly positively correlated with IL-6 and negatively correlated with IFN-γ (P < 0.05).
CONCLUSION
These results suggested that ultrasound-assisted glycation on ALA can maintain the intestinal microflora in a normal state thus balancing the proportion of Th1/Th2 to decrease allergic reaction. © 2022 Society of Chemical Industry.
Topics: Animals; Mice; Allergens; Lactalbumin; Maillard Reaction; Interleukin-4; Interleukin-6; Immunoglobulin E; Interferon-gamma; Mice, Inbred BALB C
PubMed: 36303537
DOI: 10.1002/jsfa.12293 -
Journal of Dairy Science Mar 2021α-Lactalbumin (α-LA) and β-lactoglobulin (β-LG) were isolated from yak milk and identified by mass spectrometry. The variant of α-LA (L8IIC8) in yak milk had 123...
α-Lactalbumin (α-LA) and β-lactoglobulin (β-LG) were isolated from yak milk and identified by mass spectrometry. The variant of α-LA (L8IIC8) in yak milk had 123 amino acids, and the sequence differed from α-LA from bovine milk. The amino acid at site 71 was Asn (N) in domestic yak milk, but Asp (D) in bovine and wild yak milk sequences. Yak β-LG had 2 variants, β-LG A (P02754) and β-LG E (L8J1Z0). Both domestic yak and wild yak milk contained β-LG E, but it was absent in bovine milk. The amino acid at site 158 of β-Lg E was Gly (G) in yak but Glu (E) in bovine. The yak α-LA and β-LG secondary structures were slightly different from those in bovine milk. The denaturation temperatures of yak α-LA and β-LG were 52.1°C and 80.9°C, respectively. This study provides insights relevant to food functionality, food safety control, and the biological properties of yak milk products.
Topics: Animals; Cattle; Lactalbumin; Lactoglobulins; Milk; Milk Proteins; Whey Proteins
PubMed: 33358811
DOI: 10.3168/jds.2020-18546 -
Nutrition Reviews Jun 2018α-Lactalbumin is a whey protein that constitutes approximately 22% of the proteins in human milk and approximately 3.5% of those in bovine milk. Within the mammary... (Review)
Review
α-Lactalbumin is a whey protein that constitutes approximately 22% of the proteins in human milk and approximately 3.5% of those in bovine milk. Within the mammary gland, α-lactalbumin plays a central role in milk production as part of the lactose synthase complex required for lactose formation, which drives milk volume. It is an important source of bioactive peptides and essential amino acids, including tryptophan, lysine, branched-chain amino acids, and sulfur-containing amino acids, all of which are crucial for infant nutrition. α-Lactalbumin contributes to infant development, and the commercial availability of α-lactalbumin allows infant formulas to be reformulated to have a reduced protein content. Likewise, because of its physical characteristics, which include water solubility and heat stability, α-lactalbumin has the potential to be added to food products as a supplemental protein. It also has potential as a nutritional supplement to support neurological function and sleep in adults, owing to its unique tryptophan content. Other components of α-lactalbumin that may have usefulness in nutritional supplements include the branched-chain amino acid leucine, which promotes protein accretion in skeletal muscle, and bioactive peptides, which possess prebiotic and antibacterial properties. This review describes the characteristics of α-lactalbumin and examines the potential applications of α-lactalbumin for human health.
Topics: Adult; Amino Acids; Amino Acids, Essential; Animals; Cattle; Child Development; Dietary Supplements; Female; Humans; Infant; Infant Formula; Infant Nutritional Physiological Phenomena; Lactalbumin; Male; Milk, Human; Nutritional Status
PubMed: 29617841
DOI: 10.1093/nutrit/nuy004 -
Food Chemistry Mar 2022Ellagic acid possesses numerous bioactivities such as antioxidant activity and anti-inflammatory effect. In this work, the binding interaction between ellagic acid and...
Ellagic acid possesses numerous bioactivities such as antioxidant activity and anti-inflammatory effect. In this work, the binding interaction between ellagic acid and α-lactalbumin was investigated by multi-spectroscopy and the results suggested that ellagic acid could change the conformation of α-lactalbumin. Chromatographic analysis proved the interaction of α-lactalbumin with ellagic acid taken place in less than 30 min and this interaction was stable. Computer simulations showed that both aromatic clusters Ⅰ and Ⅱ of α-lactalbumin were active sites for ellagic acid. Interestingly, both the results of molecular docking and molecular dynamics simulations suggested that ellagic acid tended to bind to aromatic cluster Ⅱ rather than aromatic cluster Ⅰ. Moreover, α-lactalbumin could enhance the antioxidant property of ellagic acid, indicating that the solubility of ellagic acid might be improved by combining α-lactalbumin. Overall, this work suggested that α-lactalbumin exhibited binding affinity for ellagic acid and enhanced its antioxidant property.
Topics: Antioxidants; Ellagic Acid; Lactalbumin; Molecular Docking Simulation; Molecular Dynamics Simulation
PubMed: 34634588
DOI: 10.1016/j.foodchem.2021.131307 -
Protein and Peptide Letters 2016Since camel milk has been attributed with various medicinal properties not found in bovine milk, we are systematically examining the differences between different...
Since camel milk has been attributed with various medicinal properties not found in bovine milk, we are systematically examining the differences between different proteins in bovine and camel milk. The purpose of this study is to investigate the structural differences between the bovine and camel α- lactalbumins. α-Lactalbumin is a highly abundant protein present in the milk of all mammalian species. Here we found several structural differences between bovine and camel α-lactalbumins: camel protein is more stable towards thermal and pHmediated denaturation but less stable towards guanidine hydrochloride-mediated unfolding, aggregates faster and is predicted to be more disordered than bovine α- lactalbumin.
Topics: Animals; Camelus; Circular Dichroism; Guanidine; Lactalbumin; Milk Proteins; Protein Aggregates; Protein Structure, Secondary; Protein Unfolding
PubMed: 27184498
DOI: 10.2174/0929866523666160517123738 -
International Journal of Biological... Jul 2018I read with great interest the paper by Dehvari and Ghahghaei (Dehvari and Ghahghaei, 2018 [1]). Their paper aimed to prove that biosynthesized AgNPs mediated by...
I read with great interest the paper by Dehvari and Ghahghaei (Dehvari and Ghahghaei, 2018 [1]). Their paper aimed to prove that biosynthesized AgNPs mediated by Pulicaria undulata L. has the capability in inhibiting amyloid fibril formation and thus could be considered as a therapeutic agent in the treatment of amyloidosis disorders. According to the literature (Jangholi et al., 2018 [2]), Thioflavin T (ThT) is a commonly used probe to monitor in vitro amyloid fibril formation. Also, since ThT fluorescence originates only from the bound population of the dye molecules, the several orders of magnitude increase in the fluorescence intensity makes ThT an unusually sensitive and efficient reporter. The authors used ThT to monitor in vitro amyloid fibril formation of α-lactalbumin and fluorescence emission spectra were recorded upon titration of the indicated concentrations of nanoparticles or α-casein. They excited the assay solutions at 450nm and the emissions were measured over the range 460-600nm. Interestingly, upon binding to α-lactalbumin's amyloid fibrils, ThT displayed a (slight) relative increase of fluorescence signal at approximately ~530-540nm, when excited at 450nm with no background ThT fluorescence subtraction/reportage. Upon binding to amyloid fibrils, ThT generally exhibits a dramatic shift of the excitation maximum (from 385nm to 450nm) and the emission maximum from 445nm to the higher wavelengths, along with a strong fluorescence signal at ~482nm (Biancalana, 1804 [3]). Regarding the wavelength of ThT fluorescence maxima, the obtained results by Dehvari and Ghahghaei are inconsistent with what has yet been reported in the literature. Moreover, the respected authors, in the present work, have not tried to describe these unusual ThT results. However, I could not find evidence/fingerprint of "cotton effect" of ThT and/or absorption flattening within the results.
Topics: Amyloid; Amyloidosis; Caseins; Fluorescent Dyes; Humans; Lactalbumin; Metal Nanoparticles; Pulicaria; Silver
PubMed: 29627464
DOI: 10.1016/j.ijbiomac.2018.04.017 -
Biotechnology Progress May 2021Partial hydrolysis of whey-based α-lactalbumin (α-La) with Bacillus licheniformis protease (BLP) induces the formation of nanotubular structures in the presence of...
Partial hydrolysis of whey-based α-lactalbumin (α-La) with Bacillus licheniformis protease (BLP) induces the formation of nanotubular structures in the presence of calcium ions by a self-assembly process. α-La nanotubes (α-LaNTs) exist in the form of regular hollow strands with well-defined average dimensions. The growth of nanotubes induces the formation of stiff transparent protein gels due to the well-arranged networks that the strands can form; these gels can be used for entrapment, transportation, and target delivery of bioactive agents in the industry. High purity of α-La (free of other whey protein fractions) is desirable for nanotube formation; however, pure proteins are very expensive and not practically obtained for industrial applications. Thus, the purpose of this research was to construct α-LaNTs from an α-La preparation with lower purity and to study the gelation phenomena triggered by the self-assembled nanotubes. Some structural features of nanotube gels and their active agent-binding abilities were also investigated. A lower amount of α-LaNTs was observed when low purity α-La was used for nanotube formation. Nanotube growth induced gel formation and higher gel stiffness was obtained when compared to α-La hydrolysates. α-La was denatured after hydrolysis and self-assembly, and remarkable changes were observed in the α-helix and β-sheet domains of α-La structure. Increased intensity in Amide I and II regions indicated potential locations for binding of active agents to α-LaNTs. Whey-based α-La without much purification can be used to produce nanotubular gels and these gels can be considered carrying matrices for active agents in various industrial applications.
Topics: Circular Dichroism; Gels; Hydrolysis; Lactalbumin; Nanotubes; Protein Binding; Whey
PubMed: 33464699
DOI: 10.1002/btpr.3127 -
Journal of Agricultural and Food... Apr 2023Dipeptidyl peptidase-IV (DPP-IV) is an exopeptidase mainly present in epithelial tissues of the liver, kidney, and intestine. It is involved in the cleavage of a variety...
Dipeptidyl peptidase-IV (DPP-IV) is an exopeptidase mainly present in epithelial tissues of the liver, kidney, and intestine. It is involved in the cleavage of a variety of substrates including the incretin hormones like glucagon-like peptide-1 (GLP-1). GLP-1 binds to the GLP-1 receptors of pancreatic β-cells and leads to β-cell proliferation and increases insulin secretion through associated gene expression. In diabetes, a constant increase in the glucose level leads to glucotoxicity, which destroys pancreatic β-cells, decreases the insulin level, and further increases the blood glucose level. Inhibition of DPP-IV is one of the strategies for the treatment of type 2 diabetes. In recent years, peptides derived from a variety of dietary proteins have been reported to exhibit inhibitory activity against the DPP-IV enzyme. Such peptides should also be protected from the action of digestive enzymes to keep their bioactivity intact. Therefore, the present investigation was aimed to evaluate the in vitro DPP-IV inhibition potential and in vivo antidiabetic potential of α-lactalbumin in non-encapsulated hydrolysate (NEH), freeze-dried encapsulated hydrolysate (FDEH), and emulsified encapsulated hydrolysate (EEH) forms. Percent DPP-IV inhibition by the NEH, FDEH, and EEH after simulated gastrointestinal digestion was 36 ± 2.28, 54 ± 2.02, and 64 ± 2.02, respectively. The oral administration of the NEH, FDEH, and EEH at a dose of 300 mg/kg body weight was evaluated in nicotinamide-streptozotocin-induced type 2 diabetic experimental rats in a study of 30 days. Rats in the diabetic control group showed an increase in the blood glucose level and liver function enzymes and a decrease in GLP-1, insulin, and antioxidative enzymes. Administration of hydrolysates reversed the parameters by lowering the blood glucose level and increasing GLP-1 and insulin levels in plasma. The blood lipid profile, liver enzyme (ALT, AST, and AP) levels, and catalase and superoxide dismutase activity were also found to be normalized and better managed in experimental diabetic rats.
Topics: Rats; Animals; Hypoglycemic Agents; Diabetes Mellitus, Type 2; Lactalbumin; Blood Glucose; Diabetes Mellitus, Experimental; Dipeptidyl-Peptidase IV Inhibitors; Insulin; Glucagon-Like Peptide 1; Peptides
PubMed: 36989115
DOI: 10.1021/acs.jafc.2c08421