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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 -
Nature Biomedical Engineering Jul 2020Theranostic agents should ideally be renally cleared and biodegradable. Here, we report the synthesis, characterization and theranostic applications of fluorescent...
Theranostic agents should ideally be renally cleared and biodegradable. Here, we report the synthesis, characterization and theranostic applications of fluorescent ultrasmall gold quantum clusters that are stabilized by the milk metalloprotein alpha-lactalbumin. We synthesized three types of these nanoprobes that together display fluorescence across the visible and near-infrared spectra when excited at a single wavelength through optical colour coding. In live tumour-bearing mice, the near-infrared nanoprobe generates contrast for fluorescence, X-ray computed tomography and magnetic resonance imaging, and exhibits long circulation times, low accumulation in the reticuloendothelial system, sustained tumour retention, insignificant toxicity and renal clearance. An intravenously administrated near-infrared nanoprobe with a large Stokes shift facilitated the detection and image-guided resection of breast tumours in vivo using a smartphone with modified optics. Moreover, the partially unfolded structure of alpha-lactalbumin in the nanoprobe helps with the formation of an anti-cancer lipoprotein complex with oleic acid that triggers the inhibition of the MAPK and PI3K-AKT pathways, immunogenic cell death and the recruitment of infiltrating macrophages. The biodegradability and safety profile of the nanoprobes make them suitable for the systemic detection and localized treatment of cancer.
Topics: Animals; Apoptosis; Breast Neoplasms; Cell Death; Female; Gold; Heterografts; Lactalbumin; Lipoproteins; Magnetic Resonance Imaging; Mice; Mice, Inbred BALB C; Mitogen-Activated Protein Kinase Kinases; Nanotechnology; Optical Imaging; Phosphatidylinositol 3-Kinases; Proteomics; Theranostic Nanomedicine
PubMed: 32661307
DOI: 10.1038/s41551-020-0584-z -
European Journal of Applied Physiology Feb 2023We tested two strategies that hypothetically increase serotonin availability (α-lactalbumin consumption and a remote submaximal handgrip contraction) on estimates of... (Randomized Controlled Trial)
Randomized Controlled Trial
INTRODUCTION
We tested two strategies that hypothetically increase serotonin availability (α-lactalbumin consumption and a remote submaximal handgrip contraction) on estimates of persistent inward currents (PICs) amplitude of soleus muscle in healthy participants.
METHODS
With a randomised, double-blind, and cross-over design, 13 healthy participants performed triangular-shaped ramp contractions with their plantar flexors (20% of maximal torque), followed by a 30-s handgrip sustained contraction (40% of maximal force) and consecutive repeated triangular-shaped contractions. This was performed before and after the consumption of either 40 g of α-lactalbumin, an isonitrogenous beverage (Zein) or an isocaloric beverage (Corn-starch). Soleus motor units discharge rates were analysed from high-density surface electromyography signals. PICs were estimated by calculating the delta frequency (ΔF) of motor unit train spikes using the paired motor unit technique.
RESULTS
ΔF (0.19 pps; p = 0.001; d = 0.30) and peak discharge rate (0.20 pps; p < 0.001; d = 0.37) increased after the handgrip contraction, irrespective of the consumed supplement. No effects of α-lactalbumin were observed.
CONCLUSIONS
Our results indicate that 40 g of α-lactalbumin was unable to modify intrinsic motoneuron excitability. However, performing a submaximal handgrip contraction before the plantar flexion triangular contraction was capable of increasing ΔF and discharge rates on soleus motor units. These findings highlight the diffused effects of serotonergic input, its effects on motoneuron discharge behaviour, and suggest a cross-effector effect within human motoneurons.
Topics: Humans; Lactalbumin; Hand Strength; Muscle Contraction; Muscle, Skeletal; Electromyography; Motor Neurons; Isometric Contraction
PubMed: 36443491
DOI: 10.1007/s00421-022-05101-3 -
Trends in Biochemical Sciences Jun 2016The importance of breast milk for the growing infant is undisputed; breastfeeding decreases infantile mortality by tenfold and decreases the incidence of infectious... (Review)
Review
The importance of breast milk for the growing infant is undisputed; breastfeeding decreases infantile mortality by tenfold and decreases the incidence of infectious diseases. Despite its recognized benefits, the structural richness of breast milk has also impeded the characterization of the multiple effects of milk components on infant physiology. However, the important roles of some components of breast milk are beginning to be dissected. For instance, molecules such as immunoglobulin A (IgA) and milk oligosaccharides protect from gastrointestinal infections and influence the development of the gut microbiota. Deciphering the complex composition of breast milk brings to light multifaceted contributions that combine to make breast milk the ultimate personalized medicine.
Topics: Breast Feeding; Carbohydrate Sequence; Cytokines; Female; Galactosyltransferases; Gastrointestinal Microbiome; Gene Expression Regulation; Humans; Immunity; Immunoglobulin A; Infant; Lactalbumin; Lipopolysaccharide Receptors; Milk, Human; Oligosaccharides; Sodium-Glucose Transporter 1
PubMed: 27093946
DOI: 10.1016/j.tibs.2016.02.008 -
Journal of Biological Inorganic... Oct 2022There is limited knowledge regarding α-lactalbumin amyloid aggregation and its mechanism. We examined the formation of α-lactalbumin amyloid fibrils (α-LAF) in the...
There is limited knowledge regarding α-lactalbumin amyloid aggregation and its mechanism. We examined the formation of α-lactalbumin amyloid fibrils (α-LAF) in the presence of cations (Mg<sup>2+</sup>, Ca<sup>2+</sup>, Na<sup>+</sup>, K<sup>+</sup>, NH<sub>4</sub><sup>+</sup>, and Cs<sup>+</sup>) in the form of chloride salts at two concentrations. We have shown that studied cations affect the conformation of α-lactalbumin, the kinetics of its amyloid formation, morphology, and secondary structure of α-LAF in a different manner. The higher salts concentration significantly accelerated the aggregation process. Both salt concentrations stabilized α-lactalbumin's secondary structure. However, the presence of divalent cations resulted in shorter fibrils with less β-sheet content. Moreover, strongly hydrated Mg<sup>2+</sup> significantly altered α-lactalbumin's tertiary structure, followed by Na<sup>+</sup>, NH<sub>4</sub><sup>+</sup>, K<sup>+</sup>, and weakly hydrated Cs<sup>+</sup>. On the other hand, Ca<sup>2+</sup>, despite being also strongly hydrated, stabilized the tertiary structure, supposedly due to its high affinity towards α-lactalbumin. Yet, Ca<sup>2+</sup> was not able to inhibit α-lactalbumin amyloid aggregation.
Topics: Amyloid; Amyloidogenic Proteins; Amyloidosis; Cations; Cations, Divalent; Chlorides; Humans; Lactalbumin; Salts
PubMed: 36151481
DOI: 10.1007/s00775-022-01962-3 -
Journal of Food Science Jul 2023Protein nanostructures can be used in food applications to improve the techno-functional properties of a food formulation. This study aims to find the best conditions...
Protein nanostructures can be used in food applications to improve the techno-functional properties of a food formulation. This study aims to find the best conditions for the production and conformational change of α-lactalbumin nanostructured aggregates. The criteria to determine the best operating conditions to produce α-lactalbumin nanostructured aggregates were intensification of foaming and emulsification, techno-functional proprieties, cytotoxic, and antibacterial activity of nanostructures compared with native α-lactalbumin. Conformational alterations occurred in the α-helix and sheet-β protein structures. The size obtained by dynamic light scattering was 163.84 nm with a polydispersity index of 0.29. The nano protein improved the techno-functional property compared to the native protein. Additionally, nanostructures had no cytotoxic effect and were innocuous to bacterial activity. Thus, this study presents the best conditions to produce α-lactalbumin nanostructured aggregates with improved properties that allow new food industry applications.
Topics: Lactalbumin; Nanostructures
PubMed: 37248720
DOI: 10.1111/1750-3841.16622 -
European Review For Medical and... Jun 2023The present review focuses on the side effects that ex-obese patients face following bariatric surgery. We searched through the principal medical indexes (SCOPUS, Web of... (Review)
Review
The present review focuses on the side effects that ex-obese patients face following bariatric surgery. We searched through the principal medical indexes (SCOPUS, Web of Science, PubMed, MEDLINE) using the following words, both alone and in combinations: bariatrics; bariatric surgery; anemia; vitamin B12; cobalamin; folate; folic acid; iron; iron supplements; gut microbiota; lactalbumin; α-lactalbumin. To perform exhaustive research, we considered articles published since 1985. Bariatric surgery induces states of nutritional deficiencies. In particular, the surgery results in a drastic fall in the levels of iron, cobalamin, and folate. Despite the dietary supplements which can counteract such decrease, some limitations exist in the nutraceutical approach. Indeed, the gastrointestinal side effects of supplements, the alterations in the microbiota, and the reduced absorption induced by the surgery may impair the effect of dietary supplements, exposing the patients to the risk of developing nutritional deficiencies. Recent literature reports the effect of promising molecules to counteract such limitations, which include α-lactalbumin, a whey protein with prebiotic activities, and new pharmaceutical forms of iron supplements, namely micronized ferric pyrophosphate. If on the one hand, α-lactalbumin enhances intestinal absorption and helps in restoring a physiological microbiota, micronized ferric pyrophosphate has a high tolerability and low or null risk of gastrointestinal side effects. Bariatric surgery represents a valid solution to obesity and obesity-related disease. However, the procedure may induce deficiencies in micronutrients. Data exists on the promising activities of α-lactalbumin and micronized ferric pyrophosphate, which may help in preventing bariatric-induced anemia.
Topics: Humans; Lactalbumin; Iron; Bariatric Surgery; Obesity; Folic Acid; Dietary Supplements; Anemia; Vitamin B 12; Malnutrition; Obesity, Morbid
PubMed: 37401320
DOI: 10.26355/eurrev_202306_32822 -
Nutrients May 2023Immunoglobulin-E(IgE)-mediated hypersensitivity to cow's milk allergens is a frequent cause of severe and life-threatening anaphylactic reactions. Besides case histories...
BACKGROUND
Immunoglobulin-E(IgE)-mediated hypersensitivity to cow's milk allergens is a frequent cause of severe and life-threatening anaphylactic reactions. Besides case histories and controlled food challenges, the detection of the IgE antibodies specific to cow's milk allergens is important for the diagnosis of cow-milk-specific IgE sensitization. Cow´s milk allergen molecules provide useful information for the refined detection of cow-milk-specific IgE sensitization.
METHODS
A micro-array based on ImmunoCAP ISAC technology was developed and designated milk allergen micro-array (MAMA), containing a complete panel of purified natural and recombinant cow's milk allergens (caseins, α-lactalbumin, β-lactoglobulin, bovine serum albumin-BSA and lactoferrin), recombinant BSA fragments, and α-casein-, α-lactalbumin- and β-lactoglobulin-derived synthetic peptides. Sera from 80 children with confirmed symptoms related to cow's milk intake (without anaphylaxis: = 39; anaphylaxis with a Sampson grade of 1-3: = 21; and anaphylaxis with a Sampson grade of 4-5: = 20) were studied. The alterations in the specific IgE levels were analyzed in a subgroup of eleven patients, i.e., five who did not and six who did acquire natural tolerance.
RESULTS
The use of MAMA allowed a component-resolved diagnosis of IgE sensitization in each of the children suffering from cow's-milk-related anaphylaxis according to Sampson grades 1-5 requiring only 20-30 microliters of serum. IgE sensitization to caseins and casein-derived peptides was found in each of the children with Sampson grades of 4-5. Among the grade 1-3 patients, nine patients showed negative reactivity to caseins but showed IgE reactivity to alpha-lactalbumin ( = 7) or beta-lactoglobulin ( = 2). For certain children, an IgE sensitization to cryptic peptide epitopes without detectable allergen-specific IgE was found. Twenty-four children with cow-milk-specific anaphylaxis showed additional IgE sensitizations to BSA, but they were all sensitized to either caseins, alpha-lactalbumin, or beta-lactoglobulin. A total of 17 of the 39 children without anaphylaxis lacked specific IgE reactivity to any of the tested components. The children developing tolerance showed a reduction in allergen and/or peptide-specific IgE levels, whereas those remaining sensitive did not.
CONCLUSIONS
The use of MAMA allows for the detection, using only a few microliters of serum, of IgE sensitization to multiple cow's milk allergens and allergen-derived peptides in cow-milk-allergic children with cow-milk-related anaphylaxis.
Topics: Animals; Female; Cattle; Milk; Allergens; Caseins; Lactalbumin; Anaphylaxis; Milk Hypersensitivity; Immunoglobulin E; Peptides; Lactoglobulins; Milk Proteins
PubMed: 37242284
DOI: 10.3390/nu15102401 -
Food and Chemical Toxicology : An... Jul 2021As a dietary polyphenol, kaempferol exhibits numerous biological activities such as antioxidant and anticancer properties. However, its application is limited because of...
As a dietary polyphenol, kaempferol exhibits numerous biological activities such as antioxidant and anticancer properties. However, its application is limited because of its poor solubility and low permeability. This work aims to investigate the interaction of kaempferol with α-lactalbumin. Multiple-spectroscopic techniques were used to prove the interaction between kaempferol and α-lactalbumin. UV-vis absorption spectra suggested that the conformation of α-lactalbumin could be changed via binding with kaempferol. The fluorescence quenching test showed that kaempferol significantly quenched the intrinsic fluorescence of α-lactalbumin. Circular dichroism spectroscopy showed that the percent helicity of α-lactalbumin secondary structure increased when combined with kaempferol. In addition, the α-lactalbumin-kaempferol complex showed stronger inhibition ability on the growth of HeLa cells compared with kaempferol alone. The complex also showed higher antioxidant capacity than kaempferol alone. Molecular docking provided three predicted binding sites of α-lactalbumin for kaempferol, as well as five predicted binding poses of kaempferol. The weak intermolecular interactions were the main forces to stabilize the α-lactalbumin-kaempferol complex. Besides, the binding stability between α-lactalbumin and kaempferol was explored by molecular dynamics simulation. In conclusion, this work provides a basis for the potential application of α-lactalbumin as a delivery carrier for kaempferol owing to its nontoxic and biocompatible properties.
Topics: Animals; Antineoplastic Agents; Antioxidants; Cattle; Drug Carriers; HeLa Cells; Humans; Kaempferols; Lactalbumin; Molecular Docking Simulation; Molecular Dynamics Simulation; Protein Binding
PubMed: 34004225
DOI: 10.1016/j.fct.2021.112265 -
Food Research International (Ottawa,... Feb 2023Calcium bioaccessibility depends on the amount of soluble calcium under intestinal digestion. The changes in calcium during in vitro static digestion of α-lactalbumin...
Calcium bioaccessibility depends on the amount of soluble calcium under intestinal digestion. The changes in calcium during in vitro static digestion of α-lactalbumin and β-lactoglobulin in presence of calcium chloride (0 mM, 20 mM and 50 mM) were followed by combining electrochemical determination of free calcium with the determination of soluble calcium by inductively coupled plasma optical emission spectroscopy. α-Lactalbumin and, more evident, β-lactoglobulin were found to increase calcium bioaccessibility with increasing intestinal digestion time by around 5% and 10%, respectively, due to the complex binding of calcium to peptides formed from protein hydrolysis by gastrointestinal enzymes. In vitro digested samples of β-lactoglobulin in presence of CaCl had nearly twice as much complex bound calcium as α-lactalbumin samples. The calcium bioaccessibility decreased significantly with the increasing concentration of added calcium chloride, although the amount of calcium chloride had little effect on the extension of digestion of α-lactalbumin and β-lactoglobulin. Simulated digestion fluids were found to have a negative effect on calcium bioaccessibility, especially the presence of hydrogen phosphate, and the amount of precipitated calcium increased significantly with increasing amount of added calcium chloride. Based on analysis and visualization by sequences of the peptides formed during digestion of α-lactalbumin and β-lactoglobulin, it was observed that peptides containing aspartic acid and glutamic acid acting as calcium chelators, may prevent precipitation of calcium in the intestines and increase calcium bioaccessibility. These results provide knowledge for the design of new dairy based functional foods to prevent calcium deficiency.
Topics: Lactalbumin; Lactoglobulins; Calcium; Calcium Chloride; Calcium, Dietary; Peptides; Digestion
PubMed: 36737996
DOI: 10.1016/j.foodres.2022.112415