Interaction of beta-lactoglobulin with retinol and fatty acids and its role as a possible biological function for this protein: a review

Comparative proteomic analysis of the changes in mare milk associated with different lactation stages and management systems

Mare milk has traditionally been attributed a number of health promoting properties. However, knowledge on its composition and functionality remains scarce, with particularly limited studies on mare milk proteomics. This study deeply characterized mare milk proteome accounting for both caseins and proteins in the whey fraction, also addressing the impact of lactation stage and different management systems. Milk samples from Basque Mountain Horse breed mares belonging to three different farms and three lactation stages were analysed after in-gel and in-solution digestion using nLC-MS/MS. Among the 469 proteins identified, the content of alpha-1 antitrypsin was significantly higher in pasture-based compared to other systems. Moreover, lactation stage significantly affected the content of beta-lactoglobulin II, immunoglobulin-like domain-containing protein, interferon alpha-inducible protein 27, lactotransferrin, polypeptide N-acetylgalactosaminyltransferase, and transforming acidic coiled-coil containing protein 2. This study contributes to the deep characterization of mare milk proteome and provides new insights into the effect of different production factors.

Binding of Per- and Polyfluoroalkyl Substances to β-Lactoglobulin from Bovine Milk

Per- and polyfluoroalkyl substances (PFAS) are known for their high environmental persistence and potential toxicity. The presence of PFAS has been reported in many dairy products. However, the mechanisms underlying the accumulation of PFAS in these products remain unclear. Here, we used native mass spectrometry and molecular dynamics simulations to probe the interactions between 19 PFAS of environmental concern and two isoforms of the major bovine whey protein β-lactoglobulin (β-LG). We observed that six of these PFAS bound to both protein isoforms with low- to mid-micromolar dissociation constants. Based on quantitative, competitive binding experiments with endogenous ligands, PFAS can bind orthosterically and preferentially to β-LG's hydrophobic ligand-binding calyx. β-Cyclodextrin can also suppress binding of PFAS to β-LG owing to the ability of β-cyclodextrin to directly sequester PFAS from solution. This research sheds light on PFAS-β-LG binding, suggesting that such interactions could impact lipid-fatty acid transport in bovine mammary glands at high PFAS concentrations. Furthermore, our results highlight the potential use of β-cyclodextrin in mitigating PFAS binding, providing insights toward the development of strategies to reduce PFAS accumulation in dairy products and other biological systems.

Prior interaction of protein and lipid affects the formation of ternary complexes with starch

The effects of prior interaction between β-lactoglobulin (βLG) and lauric acid (LA) on their formation of ternary complexes with wheat starch (WS) was studied. Firstly, the interaction between βLG and LA after they were heated at different temperatures between 55 and 95 °C was characterized by fluorescence spectroscopy and molecular dynamics simulation. This showed that a greater degree of βLG-LA interaction occurred after heating at higher temperatures. The WS-LA-βLG complexes formed subsequently were analyzed by differential scanning calorimetry, X-ray diffraction, Raman and FTIR spectroscopy, which showed that as interaction of βLG and LA increased there was an inhibitory action on the formation of ternary complex with WS. Hence, we conclude that there is competition in the ternary systems between the protein and starch to interact with the lipid, and that stronger interaction of the protein and lipid may hinder the formation of ternary complexes with starch.

A novel allelic donkey β-lactogobulin I protein isoform generated by a non-AUG translation initiation codon is associated with a nonsynonymous SNP

β-Lactoglobulin I (β-LG I) is one of the most important whey proteins in donkey milk. However, to our knowledge, there has been no study focusing on the full nucleotide sequences of this gene (BLG I). Current investigation of donkey BLG I gene is very limited with only 2 variants (A and B) characterized so far at the protein level. Recently, a new β-LG I variant, with a significantly higher mass (+1,915 Da) than known variants has been detected. In this study, we report the whole nucleotide sequence of the BLG I gene from 2 donkeys, whose milk samples are characterized by the β-LG I SDS-PAGE band with a normal electrophoretic mobility (18,514.25 Da, β-LG I B1 form) the first, and by the presence of a unique β-LG I band with a higher electrophoretic mobility (20,428.5 Da, β-LG I D form) the latter. A high genetic variability was found all over the 2 sequenced BLG I alleles. In particular, 16 polymorphic sites were found in introns, one in the 5' flanking region, 3 SNPs in the 5' untranslated region and one SNP in the coding region (g.458G > A) located at the 40th nucleotide of exon 2 and responsible for the AA substitutions p.Asp28 > Asn in the mature protein. Two SNPs (g.920-922CAC > TGT and g.1871G/A) were genotyped in 93 donkeys of 2 Italian breeds (60 Ragusana and 33 Amiatina, respectively) and the overall frequencies of g.920-922CAC and g.1871A were 0.3065 and 0.043, respectively. Only the rare allele g.1871A was observed to be associated with the slower migrating β-LG I. Considering this genetic diversity and those found in the database, it was possible to deduce at least 5 different alleles (BLG I A, B, B1, C, D) responsible for 4 potential β-LG I translations. Among these alleles, B1 and D are those characterized in the present research, with the D allele of real novel identification. Haplotype data analysis suggests an evolutionary pathway of donkey BLG I gene and a possible phylogenetic map is proposed. Analyses of mRNA secondary structure showed relevant changes in the structures, as consequence of the g.1871G > A polymorphism, that might be responsible for the recognition of an alternative initiation site providing an additional signal peptide. The extension of 19 AA sequence to the mature protein, corresponding to the canonical signal peptide with an additional alanine residue, is sufficient to provide the observed molecular weight of the slower migrating β-LG I encoded by the BLG I D allele.

A Comparative Study between A Protein Based Amorphous Formulation and Other Dissolution Rate Enhancing Approaches: A Case Study with Rifaximin

Amorphous solid dispersions (ASDs) based on proteins as co-formers have previously shown promising potential to improve the solubility and bioavailability of poorly water-soluble drugs. In particular, whey proteins have shown to be promising co-formers and amorphous stabilizers in ASD formulations, including at high drug loading. In this study, the feasibility of the whey protein β-lactoglobulin (BLG) as a co-former in ASDs was compared to the more traditional ASD co-formers based on synthetic polymers (hydroxypropyl methylcellulose acetate succinate and Eudragit^® L) as well as to a nanocrystalline formulation. The poorly water-soluble drug rifaximin (RFX) was chosen as the model drug. All drug/co-former formulations were prepared as fully amorphous ASDs by spray drying at 50% (w/w) drug loading. The BLG-based ASD had the highest glass transition temperature and showed a faster dissolution rate and higher drug solubility in three release media with different pH values (1.2, 4.5, and 6.5) compared to the polymer-based ASDs and the nanocrystalline RFX. In conclusion, BLG is a promising co-former and amorphous stabilizer of RFX in ASD formulations, superior to the selected polymer-based ASD systems or the nanocrystalline formulation.

Influence of Proteins on the Absorption of Lipophilic Vitamins, Carotenoids and Curcumin - A Review

While proteins have been widely used to encapsulate, protect, and regulate the release of bioactive food compounds, little is known about the influence of co-consumed proteins on the absorption of lipophilic constituents following digestion, such as vitamins (A, D, E, K), carotenoids, and curcumin. Their bioavailability is often low and very variable, depending on the food matrix and host factors. Some proteins can act as emulsifiers during digestion. Their liberated peptides have amphiphilic properties that can facilitate the absorption of microconstituents, by improving their transition from lipid droplets into mixed micelles. Contrarily, the less well digested proteins could negatively impinge on enzymatic accessibility to the lipid droplets, slowing down their processing into mixed micelles and entrapping apolar food compounds. Interactions with mixed micelles and proteins are also plausible, as shown earlier for drugs. This review focuses on the ability of proteins to act as effective emulsifiers of lipophilic vitamins, carotenoids, and curcumin during digestion. The functional properties of proteins, their chemical interactions with enzymes and food constituents during gastro-intestinal digestion, potentials and limitations for their use as emulsifiers are emphasized and data from human, animal, and in vitro trials are summarized.

Antioxidant Activity of Milk and Dairy Products

The aim of the study was to present a review of literature data on the antioxidant potential of raw milk and dairy products (milk, fermented products, and cheese) and the possibility to modify its level at the milk production and processing stage. Based on the available reports, it can be concluded that the consumption of products that are a rich source of bioactive components improves the antioxidant status of the organism and reduces the risk of development of many civilization diseases. Milk and dairy products are undoubtedly rich sources of antioxidant compounds. Various methods, in particular, ABTS, FRAP, and DPPH assays, are used for the measurement of the overall antioxidant activity of milk and dairy products. Research indicates differences in the total antioxidant capacity of milk between animal species, which result from the differences in the chemical compositions of their milk. The content of antioxidant components in milk and the antioxidant potential can be modified through animal nutrition (e.g., supplementation of animal diets with various natural additives (herbal mixtures, waste from fruit and vegetable processing)). The antioxidant potential of dairy products is associated with the quality of the raw material as well as the bacterial cultures and natural plant additives used. Antioxidant peptides released during milk fermentation increase the antioxidant capacity of dairy products, and the use of probiotic strains contributes its enhancement. Investigations have shown that the antioxidant activity of dairy products can be enhanced by the addition of plant raw materials or their extracts in the production process. Natural plant additives should therefore be widely used in animal nutrition or as functional additives to dairy products.

Dietary lutein supplementation improves immunity and antioxidant status of captive Indian leopards (Panthera fusca)

Indian leopards kept in zoos are fed solely on carabeef on bone (CBB) diets. Carabeef contains lesser or no carotenoids. Hence, the captive Indian leopard diets are suspected to be deficient in carotenoids while their wild counterparts acquire these pigments from their natural prey. Lutein is a vital carotenoid that plays its role as an antioxidant and immunomodulator. This experiment investigates the effect of lutein supplementation on antioxidant status, immunity, and stress in captive Panthera fusca fed CBB diets. Nine leopards were used based on 3 × 3 replicated Latin square designs in the experiment. Groups CON, LUT20, and LUT40 were supplemented with 0, 20, and 40 ppm of lutein, respectively. Each experiment comprised of 10 days of wash-out period, 11 days of adaptation, and 4 days of collection. Digestibility of crude protein (CP) was higher (p < .01) in groups LUT20 and LUT40. Serum concentration of protein, globulin, urea (p < .05), total carotenoids, total antioxidant capacity (TAC), catalase (CAT) activity, and lymphocyte transformation test (LTT) index were higher (p < .001) in groups LUT20 and LUT40. Activity of superoxide dismutase (SOD) and serum concentration of immunoglobulin were higher (p < .001) in group LUT20. Serum concentration of malonaldehyde (MDA) and fecal concentration of cortisol decreased (p < .001) in groups LUT20 and LUT40. Serum concentration of total immunoglobulin (µg/ml) and LTT were higher in group LUT20. Fecal concentration of cortisol (ng/g) was lower in LUT20 and LUT40. The study concludes that supplementation of lutein at 20 ppm would improve antioxidant status and immunity and alleviate stress in captive Indian leopards.

Effect of a novel shell material-Starch-protein-fatty acid ternary nanoparticles on loading levels and in vitro release of curcumin

Preparation of ternary nanoparticles using high amylose complex, stearic acid, and soy protein isolate as shell materials and their encapsulation of curcumin were studied. The effect of curcumin in ternary nanostructures, loading capacity of the nanoparticles, its solubility and sustained release behavior in vitro are discussed. The encapsulation efficiency of the ternary nanoparticles was 87.14 ± 0.70%, and the loading rate was 16.81 μg/g. Qualitative analysis showed that curcumin addition increases the long-range and short-range ordered structure of ternary starch (TS) by changing its crystallinity. Fourier transform infrared spectroscopy showed that curcumin-TS is formed via hydrogen bonds and hydrophobic properties of the protein. An in vitro release test showed that TS particles can control the stable release of curcumin in simulated intestinal fluid. Our study provided a novel approach to high biomass encapsulation and sustained release of polyphenols.

Binding interaction of a potential statin with β-lactoglobulin: An in silico approach

This article reports the interaction between a synthetic statin, fluvastatin with bovine milk protein, β-lactoglobulin (BLG) through docking, constant pH molecular dynamics simulation (cpHMD) and binding free energy calculations. Docking provides the best fitted binding mode of the ligand with the receptor. We have carried out MD simulations of the protein and protein-ligand complex at two different pH viz. 7.0 and 1.5. We have found that the protein shows more compact behavior at pH 1.5 and this behavior is more prominent on complexation with the ligand. In support of this we have utilized the properties viz. root mean square deviations, root mean square fluctuations, radius of gyration, protein-ligand hydrogen bond and binding free energy calculations. Calculation of radius of gyration shows that the value decreases from 14.51 Å to 14.03 Å on complexation at pH 1.5. Calculations of hydrogen bonds at pH 1.5 confirms that hydrogen bonding interactions of the binding residues of the protein with the ligand provides stability to the complex. We have used molecular mechanics-generalized Born surface area (MMGBSA) method to estimate binding free energies of the protein with the ligand. MMGBSA calculations suggest that there is favorable binding interactions between the protein and the ligand with major contributions from Van der Waals interactions. We have found that the net average binding free energy is -29.394 kcal/mol that reveals a favorable binding interactions of BLG with the ligand. This study suggests that in spite of the acidic environment in the stomach BLG can act as a carrier for the acid-sensitive drug molecules such as fluvastatin because of its highly stable conformational behavior in the acidic pH.

Bulk phase behaviour vs interface adsorption: Effects of anions and isotopes on β-lactoglobulin (BLG) interactions

HYPOTHESIS

Protein adsorption is highly relevant in numerous applications ranging from food processing to medical implants. In this context, it is important to gain a deeper understanding of protein-protein and protein-surface interactions. Thus, the focus of this investigation is on the interplay of bulk properties and surface properties on protein adsorption. It was hypothesised that the type of solvent and ions in solution should significantly influence the protein's bulk and interface behaviour, which has been observed in literature and previous work for other net negatively charged, globular proteins such as bovine serum albumin (BSA).

EXPERIMENTS

The phase behaviour of β-lactoglobulin (BLG) with lanthanum chloride (LaCl₃) and iodide (LaI₃) in normal water H₂O(l) and heavy water (D₂O(l)) was established via optical microscopy and ultraviolet-visible spectroscopy. The formation of an adsorption layer and its properties such as thickness, density, structure, and hydration was investigated via neutron reflectivity, quartz-crystal microbalance with dissipation, and infra-red measurements.

FINDINGS

β-lactoglobulin does not show significant anion-induced or isotope-induced effects - neither in bulk nor at the solid-liquid interface, which deviates strongly from the behaviour of bovine serum albumin. We also provide a comprehensive discussion and comparison of protein-specific bulk and interface behaviour between bovine serum albumin and β-lactoglobulin dependent on anion, cation, solvent, and substrate properties. These findings pave the way for understanding the transition from adsorption to crystallisation.

Using the Relationship between Concentrations of Selected Whey Proteins and BHBA to Characterize the Metabolism of Dairy Cows in Early Lactation

Simple Summary

A negative energy balance alters the concentration of various fractions of cows’ milk. Moreover, key changes are observed in the fat and protein content. Therefore, by analyzing the concentration of individual proteins in milk, it is possible to indirectly monitor the health of the animal. Subclinical ruminal acidosis and ketosis are the primary economic issues in dairy farming due to non-specific symptoms, difficulty in obtaining a diagnosis and reduced milk production. The aim of the present study was to identify the relationship between the concentrations of blood β-hydroxybutyric (BHBA) and whey proteins in milk as a marker for the diagnosis of metabolic diseases. Whey proteins were significantly influenced by both the lactation phase and BHBA. Therefore, it can be concluded that whey proteins can be used as non-invasive markers for diagnosing metabolic diseases. A high concentration of β-lactoglobulin can be a marker for diagnosing ketosis. Conversely, elevated levels of α-lactalbumin may indicate the occurrence of a metabolic disorder, such as acidosis.

Abstract

A negative energy balance alters the concentration of various fractions of cows’ milk. Therefore, by analyzing the concentration of individual proteins in milk, it is possible to indirectly monitor the health of the animal. The aim of the present study was to identify the relationship between the concentrations of blood β-hydroxybutyric acid (BHBA) and whey proteins in milk as a marker for the diagnosis of metabolic diseases. The analysis included milk and blood samples from 95 Holstein-Friesian cows, which were divided into three groups that were differentiated in terms of serum BHBA levels 5–7 days post-calving: LBHBA, low level of BHBA: 0.200–0.500 mmol/L; NBHBA, optimal level of BHBA- control group: 0.500–1.200 mmol/L; HBHBA, high level of BHBA: >1.200 mmol/L. Concentrations of α-lactoalbumin in the milk after 7 days of lactation proceeded in accordance with the concentration of β-hydroxybutyric acid, as follows: LBHBA > NBHBA > HBHBA. Concentrations of β-lactoglobulin in milk after 14 days of lactation proceeded in accordance with the concentration of β-hydroxybutyric acid, as follows: LBHBA < NBHBA < HBHBA. Therefore, it can be concluded that whey proteins can be used as non-invasive markers for diagnosing metabolic diseases. A high concentration of β-lactoglobulin can be a marker for diagnosing ketosis. Conversely, elevated levels of α-lactalbumin may indicate the occurrence of a metabolic disorder, such as acidosis.

β-Lactoglobulin and Glycodelin: Two Sides of the Same Coin?

The two lipocalins, β-lactoglobulin (βLg) and glycodelin (Gd), are possibly the most closely related members of the large and widely distributed lipocalin family, yet their functions appear to be substantially different. Indeed, the function of β-lactoglobulin, a major component of ruminant milk, is still unclear although neonatal nutrition is clearly important. On the other hand, glycodelin has several specific functions in reproduction conferred through distinct, tissue specific glycosylation of the polypeptide backbone. It is also associated with some cancer outcomes. The glycodelin gene, PAEP, reflecting one of its names, progestagen-associated endometrial protein, is expressed in many though not all primates, but the name has now also been adopted for the β-lactoglobulin gene (HGNC, www.genenames.org). After a general overview of the two proteins in the context of the lipocalin family, this review considers the properties of each in the light of their physiological functional significance, supplementing earlier reviews to include studies from the past decade. While the biological function of glycodelin is reasonably well defined, that of β-lactoglobulin remains elusive.

Starch-lipid interaction alters the molecular structure and ultimate starch bioavailability: A comprehensive review

Starch bioavailability which results in eliciting postprandial glycaemic response, is a trait of great significance and is majorly influenced by the physical interaction among the matrix components governed by their molecular structure as well as dynamics. Among physical interactions limiting starch bioavailability, starch and any guest molecules like lipid interact together to alter the molecular structure into a compact V-type arrangement endorsing the processed crystallinity, thus limiting carbolytic enzymatic digestion and further bioavailability. Considering the importance of starch-lipid dynamics affecting bioavailability, intensive research based on endogenous (internal lipids which are embedded into the food matrix) as well as exogenous (those are added from outside into the food matrix during processing like cooking) lipids have been carried out, endorsing physical interactions at colloidal and microstructural levels. The shared insights on such binary (starch-lipid) interactions revealed the evolution of characterization techniques as well as their role on altering the functional and nutritional value. It is very much vital to have a thorough understanding about the mechanisms on the molecular level to make use of these matrix interactions in the most efficient way, while certain basic questions are still remaining unaddressed. Do starch - lipid complexation affects the ultimate starch bioavailability? If so, then whether such complexation ability depends on amylose - fatty acid/lipid content? Whether the complexation is influenced further by fatty acid type/concentration/chain length or saturation? Further comprehending this, whether the altered bioavailability by binary (starch-lipid) could further be affected by ternary (starch-lipid-protein) and quaternary (starch-lipid-protein-phenolics) interactions are also discussed in this comprehensive review.

Physicochemical Composition, Antioxidant Status, Fatty Acid Profile, and Volatile Compounds of Milk and Fresh and Ripened Ewes' Cheese from a Sustainable Part-Time Grazing System

We conducted the first nutritional analysis of dairy products from the traditional Roja Mallorquina sheep breed. Samples of bulk raw milk were taken twice a month from December 2015 to March 2016 from sheep fed using a part-time grazing system, and fresh soft (FC, n = 8) and ripened (RC, n = 8) cheeses were made. The variability in vitamins, total phenolic compounds (TPC), total antioxidant capacity (TAC), and fatty acid (FA) content was influenced by the cheese-making process (differences between the cheese and the original milk) and by the type of cheese-making technology (mainly related to heating, the use of starter culture, and ripening). The most notable physicochemical characteristic of the cheeses was low fat content (24.1 and 29.6 g/100 g for FC and RC). Milk and RC were characterised by major concentrations of retinol (211.4 and 233.6 μg/100 g dry matter (DM), respectively) and TPC (18.7 and 54.6 μg/100 g DM, respectively), while FC was characterised by major concentrations of retinol (376.4 μg) and α-tocopherol (361.7 μg). The fat-soluble components of the FC generally exhibited better nutritional value for human health than those of the milk and RC, with a higher level of retinol and α-tocopherol; lower values for saturated FA, atherogenic, and thrombogenic indices; and higher levels of monounsaturated FA, polyunsaturated FA, n-3, and n-6. Acids, alcohols, and ketones comprised almost 95% of the volatile compounds detected. Acetoin and products of lactose and citrate metabolism played an important role in the development of the aromatic attributes of both kinds of cheese. This preliminary study can contribute to add value to these traditional products according to healthy nutritional criteria and supports the implementation of strategies to promote their commercialisation and obtain product labelling as “pasture-fed” or specific marks.

Crocin inhibits urea-induced amyloid formation by bovine β-lactoglobulin

Crocin stabilizes the native structure of β-lactoglobulin and attenuates urea-induced unfolding and loss of β-sheet structure during amyloidogenesis.

Investigation of beta-lactoglobulin derived bioactive peptides against SARS-CoV-2 (COVID-19): In silico analysis

The coronavirus disease of 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which started in late 2019 in Wuhan, China spread to the whole world in a short period of time, and thousands of people have died due to this epidemic. Although scientists have been searching for methods to manage SARS-CoV-2, there is no specific medication against COVID-19 as of yet. Two main approaches should be followed in the treatment of SARS-CoV-2; one of which is to neutralize the virus, and the other is to inhibit the host cell membrane receptors, where SARS-CoV-2 will bind. In this study, peptides derived from beta-lactoglobulin, which inactivates both the virus and its receptors in the host cell, were identified using computer-based in silico analysis. The beta-lactoglobulin derived peptides used in this study were obtained by the treatment of goat milk whey fraction with trypsin. The structure of the peptides was characterized by the liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS), and six beta-lactoglobulin derived peptides were selected as candidate peptides. Subsequently, the effects of peptides on SARS-CoV-2 and host cells were identified using virtual screening. According to the results of this in silico analysis, Ala-Leu-Pro-Met-His-Ile-Arg (ALMPHIR) and Ile-Pro-Ala-Val-Phe-Lys (IPAVFK) peptides were evaluated as potential candidates to be used in the treatment of SARS-CoV-2 after the future in vitro and in vivo studies.

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This in silico study used a hypothesis-driven peptidomics strategy.

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The beta-lactoglobulin derived peptides have potential effects against SARS-CoV-2.

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ALMPHIR and IPAVFK are potential candidates among these peptides.

Interaction of vitamin B12 with β-lactoglobulin: a computational study

The β-Lactoglobulin (βLG) is a major whey protein that has the potential to bind various ligands; hence it is used as a model protein in protein-ligand interaction studies. Vitamin B12 is an essential nutrient for the human body, which helps in the synthesis of DNA, proteins, and the production of red blood cells. Binding interaction of vitamin B12 with βLG will help to understand the potency of βLG as a transporter for vitamin B12. Our experimental findings already showed that βLG binds with vitamin B12 successfully (Swain et al., 2020). Nevertheless, to further support our experimental results firmly, here, we have employed computational tools such as molecular docking and molecular dynamics (MD) simulation. The molecular docking technique was used to elucidate the probable binding sites and binding affinity of vitamin B12 on βLG. The docked complex of vitamin B12 with βLG was subjected to MD simulation to investigate its stability and other interaction properties over a time frame. The study revealed that the compound is stable, and vitamin B12 imposes no change to the secondary structure of the βLG. The computational results agree reasonably well with our experimental study.

On the utility of fluorescence-detection analytical ultracentrifugation in probing biomolecular interactions in complex solutions: a case study in milk

β-Lactoglobulin is the most abundant protein in the whey fraction of ruminant milks, yet is absent in human milk. It has been studied intensively due to its impact on the processing and allergenic properties of ruminant milk products. However, the physiological function of β-lactoglobulin remains unclear. Using the fluorescence-detection system within the analytical ultracentrifuge, we observed an interaction involving fluorescently labelled β-lactoglobulin in its native environment, i.e. cow and goat milk, for the first time. Co-elution experiments support that these β-lactoglobulin interactions occur naturally in milk and provide evidence that the interacting partners are immunoglobulins, while further sedimentation velocity experiments confirm that an interaction occurs between these molecules. The identification of these interactions, made possible through the use of fluorescence-detected analytical ultracentrifugation, provides possible clues to the long debated physiological function of this abundant milk protein.

Kinetic interactions of nanocomplexes between astaxanthin esters with different molecular structures and β-lactoglobulin

The influence of different fatty acid carbon chains on the kinetic interactions of nanocomplexes between esterified astaxanthin (E-Asta) and β-lactoglobulin (β-Lg) were investigated by multi-spectroscopy and molecular modeling techniques. We synthesized ten different E-Asta bound to β-Lg and formed nanocomplexes (< 300 nm). Fluorescence spectroscopy showed moderate affinities (binding constants Ka = 10³-10⁴ M^-1). Docosahexaenoic acid astaxanthin monoester (Asta-C22:6) had the strongest binding affinity towards β-Lg (Ka = 3.77 × 10⁴ M^-1). The fluorescence quenching of β-Lg upon binding of E-Asta displayed a static mechanism, with binding sites (n) equal to 1. Fourier transform infrared spectroscopy and ultraviolet-visible absorption spectroscopy revealed that E-Asta might enter the β-Lg hydrophobic cavity, leading to unfolding of the peptide chain skeleton. In summary, β-Lg and E-Asta can form stable nanocomplex emulsions to achieve an effective delivery process for E-Asta.

Locating the binding sites of citric acid and gallic acid on milk β-lactoglobulin

β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic and hydrophilic molecules. We located the binding sites of citric acid and gallic acid on β-lactoglobulin (β-LG) in aqueous solution at physiological conditions, using spectroscopic methods, thermodynamic analysis and molecular modeling. Thermodynamic parameters ΔH⁰ -9.5 to -6.9 (kJ mol^-1), ΔS⁰ 23.9 to 13.6 (J mol^-1K^-1) and ΔG⁰ -14.5 to -13.6 (kJ mol^-1) showed that acid binds protein via ionic contacts with gallic acid forming stronger protein conjugates consistent with theoretical modeling. Different amino acids are involved in gallic acid and citric acid complexation. Protein conformation was altered with reduction of β-sheet from 58% (free protein) to 46-43% and a major increase in α-helix from 11% (free protein) to 29-23% and random coil structure in the acid-protein, indicating a partial protein destabilization. Communicated by Ramaswamy H. Sarma.

Differences in Bioactive Protein and Vitamin Status of Milk Obtained from Polish Local Breeds of Cows

The aim of the study was to compare the content of selected bioactive whey proteins and lipophilic vitamins, which largely determine the bioactive status of milk, in milk obtained from local breeds of cows raised in Poland (Polish Red, White-Backed and Simmental) and Polish Holstein-Friesian cows. Basic chemical composition and content of selected bioactive compounds (β-lactoglobulin, α-lactalbumin, lactoferrin, bovine serum albumin, and vitamins: E, A, D3 and β-carotene) in 550 milk samples were analysed. The milk produced by local breeds proved to be a more valuable source of whey proteins and lipophilic vitamins than that of the Polish Holstein-Friesians. It was distinguished by its content of all bioactive compounds, including those with antioxidant properties, i.e. vitamins E, A and D3 and β-lactoglobulin, and antimicrobial properties, mainly lactoferrin. Therefore, the milk of cows of local breeds should be considered a valuable material for processing, especially at the level of the farm or small local processing plant, to produce products that are richer in health-promoting compounds. The promotion of milk from local breeds can therefore be an opportunity for the farms that raise them.

Tracking of β-Lactoglobulin Binding Compounds with Biofingerprinting Chromatogram Analysis of Natural Products

The addition of milk to tea has been shown to prevent the vascular protective effects of the tea. Thus we had an interest in evaluating the possible binding of compounds in extracts of black tea, Camellia sinensis (L.) O. Kunze, and nettle, Urtica dioica L, to β-lactoglobulin (βLG), which is the main proteinaceous component of whey. Since our previously miniaturised 96-well plate method based on fluorescence quenching is suitable only for pure compounds, we have developed a method of ultrafiltration sampling combined with HPLC to study the βLG-binding property of the extracts. The method development was made with extract of Piper nigrum L. (black pepper), because its major component is piperine, which has been earlier shown to bind to βLG. The results showed that piperine from P. nigrum was highly and rutin from U. dioica slightly bound to βLG. No components from C. sinensis were bound to βLG. We showed for the first time, that the ultrafiltration/HPLC system can be used in βLG-binding studies with plant extracts. Furthermore, we demonstrated that βLG could bind compounds from extracts and in this way either enhance, or decrease, their health benefits, for example in food preparations.

The Identification of Novel Single-Nucleotide Polymorphisms of Equine Beta-Lactoglobulin and Lactotransferrin Genes

Lactoferrin (LTF), also called lactotransferrin, is an iron-binding protein and member of transferrin family, whereas β-LG is an important milk protein and belongs to the ligand-binding protein family of lipocalins and binds retinol. Beta-lactoglobulin (β-LG) is a major whey protein and it is a member of lipocalins family. β-LG is also known as a major allergen reason of cow milk protein allergy. Yet, no information has been reported about β-LG and LTF genes in donkeys. In this study, the genetic variation of β-LG and LTF genes were analyzed via DNA sequencing in 77 donkeys, which were individuals reared in Thrace region of Turkey. Four novel SNPs are identified as g.12887G>A, g.12973G>A, g.12654G>A, and g.13057T>C in the third intron region of β-LG gene and a genetic variant g.272719G>A in the 14th intron of LTF gene. The DNA sequences of β-LG and LTF genes in donkeys are reported for the first time in this study and these sequences were deposited to NCBI GenBank database, with the accession number MK125015 and MK211165, respectively. These variations may have an effect on milk yield and content in donkeys, so further investigations are needed to prove this hypothesis and these may be candidate SNPs for donkey breeding.

Toward a Better Understanding of Starch-Monoglyceride-Protein Interactions

The aim of the present study was to investigate the interactions between maize starch (MS), β-lactoglobulin (βLG), and monoglycerides (MG) containing different fatty acids in a model system. Results from the Rapid Visco Analyzer (RVA) showed that MS-MG_C14:0 and MS-MG_C16:0 systems presented a viscosity peak during the RVA cooling and/or holding stage, while MS-MG_C18:0, MS-MG_C18:1, and MS-MG_C18:2 systems did not show obvious changes in the pasting profile. Addition of βLG altered significantly the pasting profiles of MS-MG systems in different ways, with the most obvious change observed for the MS-MG_C18:0 system. Results from differential scanning calorimetry (DSC), Raman spectroscopy, and X-ray diffraction showed that the complexes in ternary systems were more ordered than those in binary systems. The thermal transition temperatures of complexes in binary and ternary systems were similar, although the enthalpy changes were greater for ternary than for binary systems. From the above results, we concluded that addition of βLG promoted the formation of MS-MG complexes rather than the involvement of formation of ternary MS-MG-βLG complexes.

Concentration of Bioactive Components in the Milk of Simmental Cows Depending on the Feeding System

The aim of the study was to determine the yield and chemical composition of milk from TMR-(group I) and pasture-fed Simmental cows (group II). The study was conducted with second and third lactation Simmental cows between 30 and 200 days of lactation. The present research showed that compared to TMR feeding, the use of summer pasture feeding and proper supplementation with high-energy feeds allow for higher milk yield and higher nutritive value of the milk. Compared to TMR-fed cows (group I), milk from pastured cows (group II) was characterized by a more beneficial composition of protein fractions, and a higher content of α-lactalbumin, β-lactoglobulin and lactoferrin. It also contained more vitamins A and E, calcium, magnesium and iodine, and had a significantly (P≤0.05) lower cholesterol content. The milk of cows from group II contained over twice as much CLA (1.59% of all acids) and 35% more n-3 PUFA, which resulted in a more beneficial n-6/n-3 fatty acids ratio of 2.88. In addition, this milk contained significantly (P≤0.05) less saturated fatty acids (SFA) and significantly more (P≤0.05) mono-(MUFA) and polyunsaturated fatty acids (PUFA). Consequently, the MUFA:SFA and PUFA:SFA ratios in this group were more favourable at 0.448 and 0.066, respectively. Also the content of desirable fatty acids (DFA) with hypocholesterolemic effects was higher in group II, which resulted in a more beneficial DFA:OFA ratio of 0.8 in this group. In conclusion, the use of summer pasture feeding and a proper supplemented feeding ration in Simmental cows with high-energy feeds allow for high milk yield and high nutritive value of the milk.

Enhancement of Tryptic Digestibility of Milk β-Lactoglobulin Through Treatment with Recombinant Rice Glutathione/Thioredoxin and NADPH Thioredoxin Reductase/Thioredoxin Systems

β-Lactoglobulin (BLG), a member of lipocalin family, is one of the major bovine milk allergens. This protein exists as a dimer of two identical subunits and contains two intramolecular disulfide bonds that are responsible for its resistance to trypsin digestion and allergenicity. This study aimed to evaluate the effect of reduction of disulfide bonds of BLG with different rice thioredoxins (Trxs) on its digestibility and allergenicity. Therefore, the active recombinant forms of three rice Trx isoforms (OsTrx1, OsTrx20, and OsTrx23) and one rice NADPH-dependent Trx reductase isoform (OsNTRB) were expressed in Escherichia coli. Based on SDS-PAGE, HPLC analysis, and competitive ELISA, the reduction of disulfide bonds of BLG with OsNTRB/OsTrx23, OsNTRB/OsTrx1, GSH/OsTrx1, or GSH/OsTrx20 increased its trypsin digestibility and reduced its immunoreactivity. The finding of this study opens new insights for application of plant Trxs in the improvement of food protein digestibility. Especially, the use of OsTrx20 and OsTrx1 are more cost-effective than E. coli and animal Trxs due to their reduction by GSH and no need to NADPH and Trx reductase as mediator enzyme.

Reducing the allergenic capacity of β-lactoglobulin by covalent conjugation with dietary polyphenols

To help produce hypoallergenic food, this study investigated reducing the allergenicity and improving the functional properties of bovine β-lactoglobulin (βLG) by covalent conjugation with (-)-epigallo-catechin 3-gallate (EGCG) and chlorogenic acid (CA). The covalent bond between the polyphenols and the amino acid side-chains in βLG was confirmed by MALDI-TOF-MS and SDS-PAGE. Structural analysis by fluorescence spectroscopy, circular dichroism (CD) and Fourier transform infrared (FTIR) indicated that the covalent conjugate of EGCG and CA led to the changed protein structure of βLG. Western blot analysis and enzyme-linked immunosorbent assay indicated that conjugation of βLG with these polyphenols was effective in reducing the IgE-binding capacity of βLG. The conjugates maintained the retinol-binding activity without denaturation the protein and enhanced the thermal stability with high antioxidant activity. The study provides an innovative approach to producing hypoallergenic food.

Detailed fatty acid profile of milk, cheese, ricotta and by products, from cows grazing summer highland pastures

In this research two-dimensional GC was used to analyse, for the first time, the detailed fatty acid (FA) profiles of 11 dairy matrices: raw milk (evening whole, evening partially skimmed, morning whole, and vat milk), cream, fresh cheese, whey, ricotta, scotta, 6- and 12-month-ripened cheeses, obtained across artisanal cheese- and ricotta-making trials carried out during the summer period while cows were on highland pastures. Samples were collected during 7 cheese- and ricotta-making procedures carried out at 2-week intervals from bulk milk to study possible differences in the transfer and modification of FA. Compared with morning milk, evening milk had fewer de novo synthetised FA. The detailed FA profile of partially skimmed milk differed little from that of evening whole milk before skimming, but the cream obtained differed from partially skimmed milk and from fresh cheese in about half the FA, due mainly to higher contents of all de novo FA, and lower contents of n-3 and n-6 FA. Fresh cheese and whey had similar FA profiles. The ricotta manufacturing process affected the partition of FA between ricotta and scotta, the FA profile of the latter differing in terms of groups and individual FA from the former, whereas ricotta and fresh cheese had similar composition of FA. In general, there was an increase in medium-chain saturated FA, and a decrease in many polyunsaturated FA during the first 6 months of ripening, but not during the second 6 months. Two-dimensional GC yielded a very detailed and informative FA profile on all the 11 dairy products and by-products analysed.

Antivirals against animal viruses

Antivirals are compounds used since the 1960s that can interfere with viral development. Some of these antivirals can be isolated from a variety of sources, such as animals, plants, bacteria or fungi, while others must be obtained by chemical synthesis, either designed or random. Antivirals display a variety of mechanisms of action, and while some of them enhance the animal immune system, others block a specific enzyme or a particular step in the viral replication cycle. As viruses are mandatory intracellular parasites that use the host's cellular machinery to survive and multiply, it is essential that antivirals do not harm the host. In addition, viruses are continually developing new antiviral resistant strains, due to their high mutation rate, which makes it mandatory to continually search for, or develop, new antiviral compounds. This review describes natural and synthetic antivirals in chronological order, with an emphasis on natural compounds, even when their mechanisms of action are not completely understood, that could serve as the basis for future development of novel and/or complementary antiviral treatments.

Impact of the environmental conditions and substrate pre-treatment on whey protein hydrolysis: A review

Proteins in solution are subject to myriad forces stemming from interactions with each other as well as with the solvent media. The role of the environmental conditions, namely pH, temperature, ionic strength remains under-estimated yet it impacts protein conformations and consequently its interaction with, and susceptibility to, the enzyme. Enzymes, being proteins are also amenable to the environmental conditions because they are either activated or denatured depending on the choice of the conditions. Furthermore, enzyme specificity is restricted to a narrow regime of optimal conditions while opportunities outside the optimum conditions remain untapped. In addition, the composition of protein substrate (whether mixed or single purified) have been underestimated in previous studies. In addition, protein pre-treatment methods like heat denaturation prior to hydrolysis is a complex phenomenon whose progression is influenced by the environmental conditions including the presence or absence of sugars like lactose, ionic strength, purity of the protein, and the molecular structure of the mixed proteins particularly presence of free thiol groups. In this review, we revisit protein hydrolysis with a focus on the impact of the hydrolysis environment and show that preference of peptide bonds and/or one protein over another during hydrolysis is driven by the environmental conditions. Likewise, heat-denaturing is a process which is dependent on not only the environment but the presence or absence of other proteins.

Differential Expression of the Alpha S1 Casein and Beta-Lactoglobulin Genes in Different Physiological Stages of the Adani Goats Mammary Glands

Background

Milk proteins genes have been the focus of the researches as the candidate target genes that play a decisive role when animal breeding is desired.

Objectives

In the present study, the transcriptional levels of Beta-lactoglobulin (BLG) and Alpha S1 casein (CSN1S1) genes were investigated during prenatal, milking and drying times in mammary glands of the Adani goats which showed high and low breeding values.

Materials and Methods

The breeding values of the animals were estimated first by applying multi-trait random regression model. Using the biopsy gun, the mammary gland samples were taken and real-time PCR was applied to search the expression of the genes. Fixed factors of the model were the breeding value groups, sampling times and their interactions.

Results

The interactions were significant for both genes. At milking time, the high breeding value group exhibited more transcriptional levels for BLG and less transcriptional levels for CSN1S1 gene compared with the low breeding value group. The expression patterns of these genes were also different between the two breeding value groups. The maximum level of BLG and CSN1S1 transcriptions were found to occur at drying time.

Conclusions

A difference in the gene expression was observed between the two groups which indicate the change in the nucleotide sequence for transcription factor binding sites, or miRNA binding sites, otherwise in the coding regions. Therefore, the variations in the coding and promoter regions of this gene should be investigated in the further studies.

β-Lactoglobulin Influences Human Immunity and Promotes Cell Proliferation

β-Lactoglobulin (LG) is suspected to enhance or modulate human immune responses. Moreover, LG is also hypothesized to increase human cell proliferation. However, these potential functions of LG have not been directly or thoroughly addressed. In this study, we demonstrated that LG is a potent stimulator of cell proliferation using a hybridoma cell (a splenocyte fused with a myeloma cell) model. LG's ability to promote cell proliferation was lost when the protein is denatured. To further investigate the influence of LG's conformation on cell proliferation, we chemically modified LG by either carboxymethylation (CM) or acetylation and observed significantly reduced cell proliferation when the protein structure was altered. Furthermore, we proved that LG enhances cell proliferation via receptor-mediated membrane IgM receptor. These data indicated that nondenatured LG is the major component in milk that modulates cell proliferation. Collectively, our study showed that LG plays a key role in enhancing immune responses by promoting cell proliferation through IgM receptor.