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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 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 -
Methods in Molecular Biology (Clifton,... 2002
Topics: Aminoquinolines; Animals; Binding Sites; Binding, Competitive; Calcium; Chromatography, High Pressure Liquid; Fluorescent Dyes; Humans; In Vitro Techniques; Kinetics; Lactalbumin; Milk; Muramidase; Spectroscopy, Fourier Transform Infrared
PubMed: 11833349
DOI: 10.1385/1-59259-183-3:211 -
Food Chemistry Aug 2021Numerous human conditions can benefit from diets rich in proteins and bioactives, such as capsaicin (CAP), yet their effective delivery is a sensorial, scientific and...
Numerous human conditions can benefit from diets rich in proteins and bioactives, such as capsaicin (CAP), yet their effective delivery is a sensorial, scientific and technological challenge. This study hypothesized that CAP can form various complexes with native bovine alpha-lactalbumin (holo-ALA) and decalcified-ALA (apo-ALA). Calorimetric and spectroscopic techniques reveals ALA-CAP molecular complexation is spontaneous, exothermic and accompanied by various conformational changes. ITC shows the interaction stoichiometry (n) and binding constant (K) for holo-ALA to be 0.87 ± 0.03, 1.54 ± 0.23 × 10 M and for apo-ALA to be 0.64 ± 0.09, 9.41 ± 2.16 × 10 M. Molecular docking further elucidates that hydrogen bonds govern CAP binding to holo-ALA while hydrophobic interactions dominate binding to apo-ALA in a structural cleft. Finally, this work shows these interactions along with controlled aggregation can be utilized to form CAP-loaded colloids with encapsulation efficiency of 47.1 ± 1.0%. Thus, this study shows great promise in the prospective use of ALA as an edible delivery vehicle for CAP.
Topics: Animals; Capsaicin; Cattle; Chemical Phenomena; Humans; Hydrophobic and Hydrophilic Interactions; Lactalbumin; Molecular Docking Simulation; Protein Binding
PubMed: 33677213
DOI: 10.1016/j.foodchem.2021.129306 -
Archivos Latinoamericanos de Nutricion Mar 2012Alpha-Lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in... (Review)
Review
Alpha-Lactalbumin is the main whey protein in human milk rising 2,44 g/L in mature milk. It has a key function in the synthesis of lactose from glucose and galactose in the mammary gland although this compound has also other beneficial effects on the infant health due to the high proportion of essential aminoacids (tryptophan and cysteine). It seems also to increase iron absorption in the digestive track, and in in vitro experiments, linked to oleic acid (HAMLET complex), has shown anticarcinogenic effects against cellular tumor such as human papilloma. In addition, this complex has been reported to exhibit antimicrobial properties against Streptococcus pneumoniae, Haemophilus influenzae, enteropathogenic strains of Escherichia coli and Salmonella thypimurium. However, the in vivo synthesis of HAMLET complex during milk digestion has not been proved yet. Infant formula have been improved considerably during the last decades not only adapting nutrient concentrations to infants requirements but also by the addition of new bioactive ingredients such as alpha-lactalbumin, to have the same functional effect as in breast fed babies.
Topics: Female; Humans; Infant; Infant Formula; Infant Nutritional Physiological Phenomena; Intestinal Absorption; Lactalbumin
PubMed: 23477202
DOI: No ID Found -
The FEBS Journal Nov 2010Human α-lactalbumin made lethal to tumor cells (HAMLET) and equine lysozyme with oleic acid (ELOA) are complexes consisting of protein and fatty acid that exhibit... (Review)
Review
Human α-lactalbumin made lethal to tumor cells (HAMLET) and equine lysozyme with oleic acid (ELOA) are complexes consisting of protein and fatty acid that exhibit cytotoxic activities, drastically differing from the activity of their respective proteinaceous compounds. Since the discovery of HAMLET in the 1990s, a wealth of information has been accumulated, illuminating the structural, functional and therapeutic properties of protein complexes with oleic acid, which is summarized in this review. In vitro, both HAMLET and ELOA are produced by using ion-exchange columns preconditioned with oleic acid. However, the complex of human α-lactalbumin with oleic acid with the antitumor activity of HAMLET was found to be naturally present in the acidic fraction of human milk, where it was discovered by serendipity. Structural studies have shown that α-lactalbumin in HAMLET and lysozyme in ELOA are partially unfolded, 'molten-globule'-like, thereby rendering the complexes dynamic and in conformational exchange. HAMLET exists in the monomeric form, whereas ELOA mostly exists as oligomers and the fatty acid stoichiometry varies, with HAMLET holding an average of approximately five oleic acid molecules, whereas ELOA contains a considerably larger number (11- 48). Potent tumoricidal activity is found in both HAMLET and ELOA, and HAMLET has also shown strong potential as an antitumor drug in different in vivo animal models and clinical studies. The gain of new, beneficial function upon partial protein unfolding and fatty acid binding is a remarkable phenomenon, and may reflect a significant generic route of functional diversification of proteins via varying their conformational states and associated ligands.
Topics: Animals; Apoptosis; Autophagy; Chromatin; Cytoplasmic Vesicles; Fatty Acids; Humans; Lactalbumin; Models, Molecular; Muramidase; Neoplasms; Oleic Acids; Proteasome Endopeptidase Complex; Proteasome Inhibitors; Protein Binding; Protein Conformation; Protein Folding
PubMed: 20977665
DOI: 10.1111/j.1742-4658.2010.07890.x -
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 -
Molecules (Basel, Switzerland) Mar 2021Undirected modifications between food proteins and secondary plant metabolites can occur during food processing. The results of covalent interactions can alter the...
Undirected modifications between food proteins and secondary plant metabolites can occur during food processing. The results of covalent interactions can alter the functional and biological properties of the proteins. The present work studied the extent of which covalent conjugation of the bioactive metabolite benzyl isothiocyanate (BITC; a glucosinolate breakdown product) to the whey protein α-lactalbumin affects the protein's allergenicity. Additional to the immunological analysis of native untreated and BITC-modified α-lactalbumin, the analysis of antigenic properties of proteolytically digested protein derivatives was also performed by high performance thin layer chromatography and immunostaining. As a result of the chemical modifications, structural changes in the protein molecule affected the allergenic properties. In this process, epitopes are destroyed or inactivated, but at the same time, buried epitopes can be exposed or newly formed, so that the net effect was an increase in allergenicity, in this case. Results from the tryptic hydrolysis suggest that BITC conjugation sterically hindered the cleavage sites for the enzyme, resulting in reduced digestibility and allergenicity. Residual antigenicity can be still present as short peptide fragments that provide epitopes. The desire to make food safer for allergy sufferers and to protect sensitized individuals from an allergenic reaction makes it clear that the detection of food antigens is mandatory; especially by considering protein interactions.
Topics: Chromatography, Thin Layer; Humans; Isothiocyanates; Lactalbumin
PubMed: 33805932
DOI: 10.3390/molecules26071842 -
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 -
Proteins Jan 2001A mutant of alpha-lactalbumin was expressed and purified, in which His32, Thr33, Glu49, Ile59, Val99, and Tyr103 were substituted by Leu32, Glu33, Asp49, Trp59, Asn99,... (Comparative Study)
Comparative Study
A mutant of alpha-lactalbumin was expressed and purified, in which His32, Thr33, Glu49, Ile59, Val99, and Tyr103 were substituted by Leu32, Glu33, Asp49, Trp59, Asn99, and Ala103, respectively, to create a catalytic site of lysozyme in alpha-lactalbumin. The mutant catalyzed hydrolysis of the synthetic substrate, pNP-(NAcGlc)(3), with a K(M) and k(cat) of 0.160 +/- 0.00986 mmol/L and 3.39 +/- 0. 0456 x10(-5) min(-1), respectively, which was comparable with those of chicken lysozyme of 0.137 +/- 0.0153 mmol/L and 5.25 +/- 0.115 x10(-4) min(-1). By using the Isothermal Titration Calorimetre (ITC), the average binding enthalpy of the mutant or chicken lysozyme with the substrate (chitopentaose) was measured, which was 49.22 KJ/mol for the mutant and 105.47 KJ/mol for chicken lysozyme. In conclusion, the six point mutations occurring in alpha-lactalbumin could be converted into an enzyme that was 17.5-fold less efficient than chicken lysozyme but nevertheless capable of hydrolyzing the glycosidic bond.
Topics: Amino Acid Sequence; Amino Acid Substitution; Animals; Calorimetry, Differential Scanning; Catalytic Domain; Cattle; Chickens; Evolution, Molecular; Hydrolysis; Kinetics; Lactalbumin; Molecular Sequence Data; Muramidase; Mutagenesis, Site-Directed; Protein Binding; Sequence Alignment; Substrate Specificity; Thermodynamics; Trisaccharides
PubMed: 11093257
DOI: 10.1002/1097-0134(20010101)42:1<17::aid-prot30>3.0.co;2-a