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Nutrition Reviews Dec 2021The significance of dairy in human health and nutrition is gaining significant momentum as consumers continue to desire wholesome, nutritious foods to fulfill their... (Review)
Review
The significance of dairy in human health and nutrition is gaining significant momentum as consumers continue to desire wholesome, nutritious foods to fulfill their health and wellness needs. Bovine milk not only consists of all the essential nutrients required for growth and development, it also provides a broad range of bioactive components that play an important role in managing human homeostasis and immune function. In recent years, milk bioactives, including α-lactalbumin, lactoferrin, glycomacropeptide, milk fat globule membrane, and milk oligosaccharides, have been intensively studied because of their unique bioactivity and functionality. Challenges for the application of these bioactive components in food and pharmaceutical formulations are associated with their isolation and purification on an industrial scale and also with their physical and chemical instability during processing, storage, and digestion. These challenges can be overcome by advanced separation techniques and sophisticated nano- or micro-encapsulation technologies. Current knowledge about the chemistry, separation, and encapsulation technology of major bioactives derived from bovine milk and their application in the food industry is reviewed here.
Topics: Animals; Humans; Lactalbumin; Milk; Milk Proteins; Milk, Human; Nutritional Status; Oligosaccharides; Technology
PubMed: 34879147
DOI: 10.1093/nutrit/nuab099 -
Current Protein & Peptide Science 2016This is a first part of the two-part article that continues a series of reviews on the abundance and roles of intrinsic disorder in milk proteins. We introduce here... (Review)
Review
This is a first part of the two-part article that continues a series of reviews on the abundance and roles of intrinsic disorder in milk proteins. We introduce here α-lactalbumin, a small (Mr 14 200), simple, acidic (pI 4-5), Ca(2+)-binding protein that might constitute up to 20% of total milk protein. Although function (it is one of the two components of lactose synthase that catalyzes the final step of the lactose biosynthesis in the lactating mammary gland), structure (protein has two domains, a large α -helical domain and a small β -sheet domain connected by a calcium binding loop), and folding mechanisms (α-lactalbumin is well-known as a classic example of the molten globule state) of this model globular protein are relatively well understood, α-lactalbumin continues to surprise researchers and clearly continues to have high discovery potential. The goal of this review is to summarize some recent advances in the field of α-lactalbumin research and to analyze the peculiarities of the "intrinsic disorder code" of this protein.
Topics: Amino Acid Sequence; Animals; Humans; Hydrogen-Ion Concentration; Lactalbumin; Protein Conformation; Species Specificity
PubMed: 26956441
DOI: 10.2174/138920371704160405001222 -
Food Chemistry Dec 2022Food contamination and poisoning caused by bacteria will endanger human health, and the development of natural antibacterial agents is a pressing issue. We prepared...
Food contamination and poisoning caused by bacteria will endanger human health, and the development of natural antibacterial agents is a pressing issue. We prepared ALA-Car complex and demonstrated its formation by multi-spectroscopy techniques and localized surface plasmon resonance experiments. Computer simulations have shown that van der Waals forces dominate the interaction between ALA and Car. The minimum inhibitory concentration (MIC) of Car toward Gram-negative Escherichia coli was decreased from 336 μg/mL to 224 μg/mL after binding to ALA. It had little effect on the MIC of Gram-positive Staphylococcus aureus (224 μg/mL), but further proved Car had a weaker antibacterial activity than the ALA-Car complex by the spread plate method. Overall, this work demonstrated that the ALA-Car complex had significantly higher antibacterial activities than Car, further advancing the development of natural antibacterial agents.
Topics: Anti-Bacterial Agents; Cymenes; Humans; Lactalbumin; Microbial Sensitivity Tests
PubMed: 35932687
DOI: 10.1016/j.foodchem.2022.133820 -
ACS Applied Materials & Interfaces Oct 2020Skin wound especially burn injury is a major threat for public health. One of the pursuits in the current wound healing research is to identify new promising biological...
Skin wound especially burn injury is a major threat for public health. One of the pursuits in the current wound healing research is to identify new promising biological materials, which can not only promote tissue repair but also reduce scar formation. In this current study, the potentials of α-lactalbumin (ALA), a tryptophan-rich dietary protein acting as a precursor of neurotransmitter serotonin, to promote the burn wound healing and reduce the scar formation were investigated. The ALA was initially electrospun with polycaprolactone (PCL) to accomplish electrospun nanofibrous mats (ENMs), subsequently assessed for their physicochemical attributes and wound healing efficiency on a burn rat model, and then their healing mechanisms at cellular and molecular levels were explored. The results showed that ALA and PCL were physicochemically compatible in ENMs. The average diameter of various nanofibers was within 183-344 nm. Their wettability and mechanical properties could be readily modulated by adjusting the mass ratios of ALA and PCL from 1/9 to 1/2. The selected ENMs exhibited negligible cytotoxicity and satisfactory adhesion to fibroblasts and promoting the proliferation of the fibroblasts. As compared to pristine PCL based ENMs, the composite scaffolds could accelerate the wound healing process and exhibit effects comparable to a marketed wound dressing over 16 days. Moreover, the ALA/PCL based ENMs could increase the synthesis of type I collagen and decrease the expression of α-smooth muscle actin, conferring that the novel wound dressings could reduce the formation of scars. Collectively, this study demonstrates that the ALA is a promising biological material and could promote the regeneration of burn skins with reduced scar formation, when being loaded on ultrafine fibrous scaffolds, mimicking the structure of the natural extra cellular matrix.
Topics: Animals; Bandages; Biocompatible Materials; Burns; Cell Adhesion; Cell Proliferation; Lactalbumin; Male; Mice; NIH 3T3 Cells; Nanofibers; Particle Size; Rats; Rats, Sprague-Dawley; Surface Properties; Tissue Scaffolds; Wound Healing
PubMed: 32667794
DOI: 10.1021/acsami.0c05175 -
The Journal of Chemical Physics Nov 2017As proteins contain both hydrophobic and hydrophilic amino acids, they will readily adsorb onto interfaces between water and hydrophobic fluids such as oil. This...
As proteins contain both hydrophobic and hydrophilic amino acids, they will readily adsorb onto interfaces between water and hydrophobic fluids such as oil. This adsorption normally causes changes in the protein structure, which can result in loss of protein function and irreversible adsorption, leading to the formation of protein interfacial films. While this can be advantageous in some applications (e.g., food technology), in most cases it limits our ability to exploit protein functionality at interfaces. To understand and control protein interfacial adsorption and function, it is necessary to understand the microscopic conformation of proteins at liquid interfaces. In this paper, molecular dynamics simulations are used to investigate the adsorption and conformation of two similar proteins, lysozyme and α-lactalbumin, at a water-octane interface. While they both adsorb onto the interface, α-lactalbumin does so in a specific orientation, mediated by two amphipathic helices, while lysozyme adsorbs in a non-specific manner. Using replica exchange simulations, both proteins are found to possess a number of distinct interfacial conformations, with compact states similar to the solution conformation being most common for both proteins. Decomposing the different contributions to the protein energy at oil-water interfaces suggests that conformational change for α-lactalbumin, unlike lysozyme, is driven by favourable protein-oil interactions. Revealing these differences between the factors that govern the conformational change at interfaces in otherwise similar proteins can give insight into the control of protein interfacial adsorption, aggregation, and function.
Topics: Adsorption; Lactalbumin; Molecular Dynamics Simulation; Muramidase; Octanes; Protein Conformation; Water
PubMed: 29166117
DOI: 10.1063/1.4994561 -
European Journal of Applied Physiology Feb 2023The neurotransmitter serotonin has a strong effect on behaviour and motor control. Regarding motor control, serotonin contributes to the development of fatigue and is... (Randomized Controlled Trial)
Randomized Controlled Trial
PURPOSE
The neurotransmitter serotonin has a strong effect on behaviour and motor control. Regarding motor control, serotonin contributes to the development of fatigue and is also involved in the ability of motor neurones to operate across a large range of forces (gain control). The consumption of tryptophan-rich supplements (such as α-lactalbumin) is of interest because this amino acid is the only precursor for brain serotonin synthesis. Therefore, the purpose of this study was to determine the effects of α-lactalbumin supplementation on neuromuscular performance.
METHODS
Using a randomised double-blind cross-over design, 16 healthy participants performed plantar flexor and handgrip maximal voluntary contractions, a 30-s submaximal handgrip contraction, and a plantar flexor fatigue protocol before and 90 min after consuming either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (corn-starch). Sleepiness, mood, and cognition were assessed to evaluate any psychological effects.
RESULTS
α-Lactalbumin decreased force steadiness by 25% during the sustained submaximal handgrip contraction (p < 0.01) and induced greater fatigue (15% reduction in total torque-time integral, p = 0.01) during the fatigue protocol. These effects were not observed for the other control beverages. No effects were found for maximal or explosive strength, or psychological measurements.
CONCLUSIONS
40 g of α-lactalbumin increased handgrip force variability and reduced performance during fatiguing muscle contractions but did not influence brief maximal contractions or psychological parameters in healthy individuals. These findings support the hypothesis that the consumption of α-lactalbumin can increase motor neurone input-output gain and exacerbate central fatigue during sustained maximal exercise.
Topics: Humans; Lactalbumin; Cross-Over Studies; Muscle Fatigue; Hand Strength; Serotonin; Muscle Contraction; Fatigue; Electromyography; Muscle, Skeletal; Isometric Contraction
PubMed: 36443490
DOI: 10.1007/s00421-022-05103-1 -
Food & Function Feb 2020Resveratrol (RES)-loaded protein-polysaccharide nanoparticles were fabricated through simple electrostatic interactions with oppositely charged α-lactalbumin (ALA) and...
Resveratrol (RES)-loaded protein-polysaccharide nanoparticles were fabricated through simple electrostatic interactions with oppositely charged α-lactalbumin (ALA) and chitosan (CHI) with a mass ratio of 5 : 1 without the addition of NaCl at pH 6.5. The Z-average diameter and zeta-potential values of RES-ALA-CHI nanoparticles were 211.0 nm and 13.23 mV, respectively. Both TEM and AFM graphs confirmed that RES-ALA-CHI nanoparticles had a spherical shape, and were dispersed homogeneously at the nanoscale. The encapsulation efficiency (EE) and loading amount (LA) of RES in RES-ALA-CHI nanoparticles were 58.86% and 196.2 μg mg-1, respectively, in the presence of 400 μg mL-1 RES. XRD results confirmed that RES was in amorphous form in ALA-CHI nanoparticles. The interaction between RES and ALA-CHI nanoparticles was mainly driven by hydrophobic interaction and hydrogen bonding. Compared to RES (free), the UV light and heat stability, in vitro bioaccessibility, and antioxidant activity of RES in RES-ALA-CHI nanoparticles were pronouncedly enhanced. The information provided in this study should be of interest to the food industry to fabricate robust nanoscale delivery systems with ALA-CHI nanoparticles for RES and other hydrophobic bioactive compounds.
Topics: Antioxidants; Biphenyl Compounds; Chitosan; Drug Carriers; Drug Stability; Hydrophobic and Hydrophilic Interactions; Lactalbumin; Nanoparticles; Particle Size; Picrates; Resveratrol
PubMed: 31995080
DOI: 10.1039/c9fo01998g -
Journal of Chromatography. A Feb 2023The phenomenon of protein-protein association on multimodal chromatography resins was described for two different case study examples. The adsorption pattern of...
The phenomenon of protein-protein association on multimodal chromatography resins was described for two different case study examples. The adsorption pattern of single-component solutions of calcium-rich alpha-lactalbumin (aLaCa) and calcium-depleted alpha-lactalbumin (aLa) and their mixtures with bovine serum albumin was determined on a multimodal anion-exchange chromatography medium. In single-component solutions, both aLaCa and aLa exhibited identical adsorption behavior at low resin loadings, whereas at high loadings the adsorption strength of aLa markedly exceeded that of alaCa. In binary mixtures, the adsorption of BSA enhanced at high concentrations of aLa or aLaCa in the adsorbed phase. The unusual adsorption patterns observed were attributed to the tendency of the proteins for molecular association in the adsorbed phase in single and binary solutions. The phenomena was examined for different pH of the solution: pH 6, 7, 8, and different solvent environments: phosphate buffer (PB), bis tris buffer (BT), 100 mM NaCl in BT and bis tris propane buffer (BTP). The strongest effect was observed for PB and for 100 mM NaCl in BT. Its occurrence was also evidenced for other case study example, i.e., adsorption of single-component solutions and binary mixtures of a monoclonal antibody (mAb) and lysozyme (LYZ) on a multimodal cation-exchange chromatography medium. The enhancement of adsorption of mAb was observed at high concentrations of LYZ in the adsorbed phase. To quantify the underlying effects, a mechanistic model was used, which accounted for both protein association and exclusion resulting from attractive and repulsive protein-protein iterations in the adsorbed phase.
Topics: Lactalbumin; Calcium; Sodium Chloride; Chromatography; Serum Albumin, Bovine; Adsorption
PubMed: 36731331
DOI: 10.1016/j.chroma.2023.463827 -
Nutrients Nov 2021Frozen storage is necessary to preserve expressed human milk for critically ill and very preterm infants. Milk pasteurization is essential for donor milk given to this... (Review)
Review
Frozen storage is necessary to preserve expressed human milk for critically ill and very preterm infants. Milk pasteurization is essential for donor milk given to this special population. Due to these storage and processing conditions, subtle changes occur in milk nutrients. These changes may have clinical implications. Potentially, bioactive complexes of unknown significance could be found in human milk given to preterm infants. One such complex, a cytotoxic α-lactalbumin-oleic acid complex named "HAMLET," (Human Alpha-Lactalbumin Made Lethal to Tumor cells) is a folding variant of alpha-lactalbumin that is bound to oleic acid. This complex, isolated from human milk casein, has specific toxicity to both carcinogenic cell lines and immature non-transformed cells. Both HAMLET and free oleic acid trigger similar apoptotic mechanisms in tissue and stimulate inflammation via the NF-κB and MAPK p38 signaling pathways. This protein-lipid complex could potentially trigger various inflammatory pathways with unknown consequences, especially in immature intestinal tissues. The very preterm population is dependent on human milk as a medicinal and broadly bioactive nutriment. Therefore, HAMLET's possible presence and bioactive role in milk should be addressed in neonatal research. Through a pediatric lens, HAMLET's discovery, formation and bioactive benefits will be reviewed.
Topics: Caseins; Cytotoxins; Diet; Food Handling; Food Storage; Humans; Infant, Newborn; Infant, Premature; Lactalbumin; Milk, Human; Oleic Acids
PubMed: 34959888
DOI: 10.3390/nu13124336 -
Nutrients Aug 2022To date, the involvement of α-Lactalbumin (α-LA) in the management of polycystic ovary syndrome (PCOS) refers to its ability to improve intestinal absorption of... (Review)
Review
To date, the involvement of α-Lactalbumin (α-LA) in the management of polycystic ovary syndrome (PCOS) refers to its ability to improve intestinal absorption of natural molecules like inositols, overcoming the inositol resistance. However, due to its own aminoacidic building blocks, α-LA is involved in various biological processes that can open new additional applications. A great portion of women with PCOS exhibit gastrointestinal dysbiosis, which is in turn one of the triggering mechanisms of the syndrome. Due to its prebiotic effect, α-LA can recover dysbiosis, also improving the insulin resistance, obesity and intestinal inflammation frequently associated with PCOS. Further observations suggest that altered gut microbiota negatively influence mental wellbeing. Depressive mood and low serotonin levels are indeed common features of women with PCOS. Thanks to its content of tryptophan, which is the precursor of serotonin, and considering the strict link between gut and brain, using α-LA contributes to preserving mental well-being by maintaining high levels of serotonin. In addition, considering women with PCOS seeking pregnancy, both altered microbiota and serotonin levels can induce later consequences in the offspring. Therefore, a deeper knowledge of potential applications of α-LA is required to transition to preclinical and clinical studies extending its therapeutic advantages in PCOS.
Topics: Dysbiosis; Female; Humans; Inositol; Insulin Resistance; Lactalbumin; Polycystic Ovary Syndrome; Pregnancy; Serotonin
PubMed: 35956395
DOI: 10.3390/nu14153220