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The FEBS Journal Apr 2013Thirteen years ago, α-lactalbumin (α-LA) was first reported to form a complex with oleic acid (OA). This complex, called HAMLET (human α-lactalbumin made lethal to... (Review)
Review
Thirteen years ago, α-lactalbumin (α-LA) was first reported to form a complex with oleic acid (OA). This complex, called HAMLET (human α-lactalbumin made lethal to tumour cells), was found to be cytotoxic to cancer cells. In HAMLET, α-LA assumes a partially unfolded conformation and can bind OA in various stoichiometries. Subsequently, different groups have been able to prepare HAMLET-like cytotoxic complexes in different ways, which all involve the destabilization of α-LA, and a number of different proteins have been able to form similar complexes. This suggests that the ability to form stable complexes with lipids may be a generic feature of the polypeptide chain, although the precise structural and functional details may vary from protein to protein. We review the biophysical and biochemical properties of this class of complexes, focusing on different methods of preparation, complex structure and the role of the protein and the lipid within these complexes. The cellular effects of these complexes are multifaceted and depend on the cell types. There are strong indications that OA has an essential role, whereas the protein component, rather than having a toxic effect on its own, functions as a vehicle for transporting the toxic OA to the cells and keeping the OA in solution. Fatty acids alone can affect numerous cellular signalling and metabolic pathways, in addition to playing important roles in immune responses and inflammatory processes. Further studies will aim to determine how the molecular properties of the different protein-lipid complexes correlate with their biological efficacy.
Topics: Animals; Fatty Acids; Humans; Lactalbumin; Oleic Acid; Oleic Acids; Protein Folding; Proteins
PubMed: 23441831
DOI: 10.1111/febs.12204 -
International Immunopharmacology Dec 2022Cardiovascular aging is the most important factor leading to cardiovascular disease (CVD), and the incidence and severity of cardiovascular events increase with age....
Cardiovascular aging is the most important factor leading to cardiovascular disease (CVD), and the incidence and severity of cardiovascular events increase with age. Cardiovascular disease is one of the leading causes of death in the aging population. Therefore, it is extremely urgent to develop and explore effective drugs or bioactive molecules to prevent cardiovascular aging and related diseases. In the current work, the effect of bovine α-lactalbumin (α-lactalbumin is one of the major bioactive protein molecules in milk) on cardiovascular aging was investigated in vitro and in vivo. First, a cellular model of cardiovascular aging was established using HO-induced in vitro cellular models. It was found that α-lactalbumin could alleviate cardiovascular senescence by assessing Sa-β-gal and senescence-related markers (such as p16/p21/p53) in in vitro cellular models. Bovine α-lactalbumin attenuated aging-related inflammation and oxidative stress. Furthermore, aged mice were used as an in vivo cardiovascular aging model. We explored the effect of α-lactalbumin on cardiovascular aging and found that cardiovascular aging was significantly attenuated by evaluating Sa-β-gal staining and aging-related marker molecules. Mechanistically, we found that α-lactalbumin may alleviate cardiovascular aging by regulating the expression of Sirt1 (Sirtuin 1). In summary, in the current work, we systematically explored the potential biological activity of α-lactalbumin against cardiovascular aging and found that α-lactalbumin has good anti-aging potential in vitro and in vivo, suggesting that α-lactalbumin could be used as an antiaging functional food in the future.
Topics: Mice; Cattle; Animals; Lactalbumin; Cellular Senescence; Hydrogen Peroxide; Cardiovascular Diseases; Aging; Sirtuin 1
PubMed: 36252495
DOI: 10.1016/j.intimp.2022.109291 -
Ultrasonics Sonochemistry Mar 2021α-lactalbumin was modified by ultrasound (US, 20 kHz, 43 ± 3.4 W/cm) pre-treatments (0, 15, 30 and 60 min) and laccase cross-linking of sonicated α-lactalbumin...
α-lactalbumin was modified by ultrasound (US, 20 kHz, 43 ± 3.4 W/cm) pre-treatments (0, 15, 30 and 60 min) and laccase cross-linking of sonicated α-lactalbumin was used to evaluate the physical and oxidative stability of conjugated linoleic acid (CLA) emulsions. The emulsions prepared with laccase cross-linking US-α-lactalbumin (α-lactalbumin treated with US pre-treatment) and US-α-lactalbumin were scrutinized for oxidative and physical stability at room temperature for two weeks of storage. Laccase cross-linking US-α-lactalbumin (Lac-US-α-lactalbumin) revealed improved physical stability in comparison with US-α-lactalbumin, specified by droplet size, structural morphology, adsorbed protein, emulsifying properties and creaming index. SDS-PAGE analysis showed that there was formation of polymers in Lac-US-α-lactalbumin emulsion. Surface hydrophobicity of Lac-US-α-lactalbumin was higher than that of US-α-lactalbumin, and gradually enhanced with the increase of ultrasound time. More importantly, the measurements of peroxide values and conjugated dienes were used to study the oxidative stability of the CLA emulsions. The Lac-US-α-lactalbumin emulsion proved to be reducing the synthesis of fatty acid hydroperoxides and less conjugated dienes compared to the native and US-α-lactalbumin emulsions. This study revealed that the combination of US pre-treatment and laccase cross-linking might be an effective technique for the modification of CLA emulsions.
Topics: Adsorption; Electric Conductivity; Emulsions; Hydrogen-Ion Concentration; Laccase; Lactalbumin; Linoleic Acids, Conjugated; Oils; Oxidation-Reduction; Sonication; Temperature; Water
PubMed: 33125963
DOI: 10.1016/j.ultsonch.2020.105365 -
Journal of Dairy Science Sep 2020Despite extensive research on the topic, valorization of dairy by-products remains challenging. Cheese whey is of particular interest because it contains valuable...
Despite extensive research on the topic, valorization of dairy by-products remains challenging. Cheese whey is of particular interest because it contains valuable proteins such as α-lactalbumin (α-LA) and β-lactoglobulin (β-LG). However, selective fractionation of these 2 proteins into pure fractions is complex because of their similar molecular weights. In this study, we proposed an innovative protein separation strategy based on coupling high hydrostatic pressure (HHP) with acidification of whey at pH 4.6. We investigated the effect of single-cycle HHP (600 MPa) for 5, 10, and 15 min and multiple-cycle HHP (1-3 cycles of 5 min at 600 MPa) on α-LA and β-LG fractionation from cheese whey at initial pH (control, pH 6.66) and acidified to pH 4.6. All pressurization conditions with acidified whey induced a drastic aggregation of β-LG compared with control whey. The highest degrees of purification (75 and 98%, respectively) and yields (95 and 88%, respectively) of α-LA and β-LG were obtained with the application of single-cycle HHP treatment of acidified whey at pH 4.6 at 600 MPa for 5 min. Our results showed the strong potential of using HHP as an innovative tool for the fractionation of valuable proteins such as α-LA from cheese whey.
Topics: Cheese; Chemical Fractionation; Hydrostatic Pressure; Lactalbumin; Lactoglobulins; Whey
PubMed: 32622608
DOI: 10.3168/jds.2019-17817 -
Journal of Dairy Science May 2014To study the feasibility of promoting iron absorption by peptides derived from α-lactalbumin and β-lactoglobulin, the present work examined the transport of iron...
To study the feasibility of promoting iron absorption by peptides derived from α-lactalbumin and β-lactoglobulin, the present work examined the transport of iron across Caco-2 monolayer cell as in vitro model. Caco-2 cells were seeded in bicameral chambers with α-lactalbumin hydrolysate-Fe (α-LAH-Fe) complex and β-lactoglobulin hydrolysate-Fe (β-LGH-Fe) complex, α-LAH and iron mixture, β-LGH and iron mixture, FeSO4 and ascorbic acid mixture, and FeSO4. In addition, the cytotoxicity of α-LAH-Fe and β-LGH-Fe complexes were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The iron absorption and ferritin content were assessed using the coupled in vitro digestion/Caco-2 cell model. Results support that peptide-iron complexes can promote ferritin formation and it is possible to apply β-LGH-Fe complexes as iron-fortified supplements with high iron absorbability.
Topics: Biological Transport; Caco-2 Cells; Ferritins; Humans; Iron; Lactalbumin; Lactoglobulins; Protein Hydrolysates
PubMed: 24612808
DOI: 10.3168/jds.2013-7461 -
FASEB Journal : Official Publication of... Jan 1996The molten globule state of alpha-lactalbumin is the best-characterized folding intermediate of globular proteins and has been studied intensively by various... (Review)
Review
The molten globule state of alpha-lactalbumin is the best-characterized folding intermediate of globular proteins and has been studied intensively by various spectroscopic and physiochemical techniques, including stopped-flow CD and fluorescence spectroscopies, a hydrogen-exchange technique, 1H-NMR spectroscopy, disulfide-exchange chemistry, site-directed mutagenesis, and calorimetric techniques. This review summarizes recent studies. Major findings about the structure of the molten globule state are: 1) It is highly heterogeneous, having a highly structured alpha-helical domain with the beta-sheet domain being significantly unfolded; and 2) it is not a nonspecific, collapsed polypeptide but already has a native-like tertiary fold. These structural characteristics are essential to fully understand the thermodynamic properties of the molten globule state which are described in connection with a recently proposed computational approach to predict the structure of the molten globule state of a protein. Mutant proteins in which the stability of the molten globule state was changed were constructed. Studies of the equilibrium unfolding and kinetic refolding of the mutant proteins will provide further insight into the molten globule state as a folding intermediate. In spite of an initial expectation that the structure recognized by an Escherichia coli chaperone, GroEL, is the molten globule, the interaction of GroEL with alpha-lactalbumin in the molten globule state is much weaker than the interaction with more unfolded states of alpha-lactalbumin, a disulfide-reduced form, and disulfide rearranged species.
Topics: Animals; Lactalbumin; Molecular Chaperones; Protein Folding; Protein Structure, Secondary; Protein Structure, Tertiary; Thermodynamics
PubMed: 8566530
DOI: 10.1096/fasebj.10.1.8566530 -
Scientific Reports Apr 2021To verify whether myo-inositol plus α-lactalbumin may reduce insulin resistance and excessive fetal growth in women with gestational diabetes mellitus. In a 12-month... (Randomized Controlled Trial)
Randomized Controlled Trial
To verify whether myo-inositol plus α-lactalbumin may reduce insulin resistance and excessive fetal growth in women with gestational diabetes mellitus. In a 12-month period, 120 women with a diagnosis of gestational diabetes mellitus were consecutively enrolled with an allocation of 1:1 in each group and randomly treated with myo-inositol plus α-lactalbumin plus folic acid (treated group) or folic acid (control group) for 2 months. Primary outcome was the variation of insulin resistance through the study evaluated by HOMA-IR. Secondary outcome was the evaluation, through the study, of fetal growth by ultrasound measurements of abdominal circumference centiles and estimated fat thickness. Some clinical outcomes were also considered. After 2 months, in the treated group, a significant reduction in insulin resistance (HOMA values 3.1 ± 1.4 vs 6.1 ± 3.4, p = 0.0002) and fetal growth was shown (Abdominal circumference centiles 54.9 ± 23.5 vs 67.5 ± 22.6, P = 0.006). Among clinical outcomes, a significant decrease in the rate of women who needed insulin (6.7% vs 20.3%, p = 0.03) and of pre-term birth (0 vs 15.2%, p = 0.007) was evidenced. A combination of myo-inositol and α-lactalbumin may reduce insulin resistance and excessive fetal growth.Clinical trial registration: ClinicalTrials.gov, http://www.clinicaltrials.gov , NCT03763669, first posted date 04/12/2018; last posted date December 06/12/2018.
Topics: Adult; Birth Weight; Case-Control Studies; Diabetes, Gestational; Dietary Supplements; Female; Folic Acid; Humans; Inositol; Insulin Resistance; Lactalbumin; Pregnancy; Pregnancy Outcome
PubMed: 33893377
DOI: 10.1038/s41598-021-88329-x -
Food Chemistry Jan 2022We used computational molecular dynamics (MD) to assess molecular conformations of apo- and holo-forms (respectively without and with Ca) of bovine α-lactalbumin...
We used computational molecular dynamics (MD) to assess molecular conformations of apo- and holo-forms (respectively without and with Ca) of bovine α-lactalbumin (α-La) at different temperatures, and to correlate them with the protein's foaming properties. At 4 °C and 25 °C no major protein conformation changes occurred. At 75 °C, lots of changes were evidenced: the Ca depletion triggered the complete loss of h2b, h3c helices and S1, S2 and S3 β-sheets, and partial losses of H1, H2 and H3 α-helices. The absence of Ca in apo-α-La and its leaving from holo-α-La triggered electrostatic repulsion among Asp82, Asp84 and Asp87, leading to the formation of a hydrophobic cluster involving Phe9, Phe31, Ile1, Va42, Ile55, Phe80 and Leu81. These conformational changes were related to an interfacial tension decrease and to a foaming capacity increase, for both apo-α-La and holo-α-La. This study exemplifies how powerful MD is as a tool to provide a better understanding of the molecular origins of food proteins' techno-functionalities.
Topics: Animals; Cations; Cattle; Lactalbumin; Molecular Dynamics Simulation; Protein Structure, Secondary; Temperature
PubMed: 34375890
DOI: 10.1016/j.foodchem.2021.130733 -
Journal of Dairy Science Jun 2020The objective of this study was to evaluate the protection conferred by lactoferrin, α-lactalbumin, and β-lactoglobulin in cerebral ischemia reperfusion (I/R) injury....
Investigation and comparison of the protective activities of three functional proteins-lactoferrin, α-lactalbumin, and β-lactoglobulin-in cerebral ischemia reperfusion injury.
The objective of this study was to evaluate the protection conferred by lactoferrin, α-lactalbumin, and β-lactoglobulin in cerebral ischemia reperfusion (I/R) injury. Rat pheochromocytoma (PC12) cells were used to construct an oxygen and glucose deprivation model in vitro, and ICR mice underwent carotid artery "ligation-relaxation" to construct a cerebral I/R injury model in vivo. The levels of toll-like receptor 4 (TLR4) and downstream factors including nuclear factor-κB, tumor necrosis factor-α, and IL-1β were measured. Metabonomics detection and data mining were conducted to identify the specific metabolic sponsor of the 3 proteins. The results showed that lactoferrin, α-lactalbumin, and β-lactoglobulin protected neurons from cerebral I/R injury by increasing the level of bopindolol and subsequently inhibiting the TLR4-related pathway to different degrees; β-lactoglobulin had the strongest activity of the 3 proteins. In summary, this study is the first to investigate and compare the protective effects of lactoferrin, α-lactalbumin, and β-lactoglobulin in a cerebral stroke model. The results implicate TLR4 as a novel target of the 3 bioactive proteins to prevent cerebral I/R injury.
Topics: Animals; Glucose; Interleukin-1beta; Lactalbumin; Lactoferrin; Lactoglobulins; Male; Mice; Mice, Inbred ICR; NF-kappa B; Oxygen; PC12 Cells; Rats; Reperfusion Injury; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha
PubMed: 32229112
DOI: 10.3168/jds.2019-17725 -
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