Статті в журналах: "Protein-caseins"

1

Davies, D. Thomas, and Andrew J. R. Law. "Quantitative fractionation of casein mixtures by fast protein liquid chromatography." Journal of Dairy Research 54, no. 3 (August 1987): 369–76. http://dx.doi.org/10.1017/s0022029900025541.

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SummaryAlkylation of whole casein samples by reaction with cysteamine and cystamine in a bis-tris-propane–urea buffer (pH 7·0) followed by fast protein liquid chromatography (FPLC) at 20°C on a Mono Q HR5/5 column in the same buffer and using a NaCl gradient led to good resolution of the whole casein into fractions representing (i) γ2- plus γ3-caseins, (ii) κ-caseins, (iii) β-casein, (iv) αs2-caseins and (v) αsl-caseins, together with small amounts of unidentified materials. Quantitatively the FPLC values agreed well with those for αs1-, β-, αs2- and γ2- plus γ3-caseins obtained by ion-exchange chromatography on DEAE cellulose, Whatman DE52 and with those for º-caseins obtained by gel-permeation chromatography on Sephadex G–150.

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2

Turner, M. D., S. E. Handel, C. J. Wilde, and R. D. Burgoyne. "Differential effect of brefeldin A on phosphorylation of the caseins in lactating mouse mammary epithelial cells." Journal of Cell Science 106, no. 4 (December 1, 1993): 1221–26. http://dx.doi.org/10.1242/jcs.106.4.1221.

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The major milk proteins, the caseins, contain multiple phosphorylation sites. Phosphorylation of the caseins is necessary to allow Ca2+ binding and aggregation of the caseins to form micelles. We have followed the phosphorylation of the caseins in isolated acini from lactating mouse mammary gland. Incubation of mammary cells with [32P]orthophosphate revealed that phosphorylation of newly synthesised caseins was complete within 20 minutes of synthesis. Extensive secretion of alpha-, beta- and gamma-caseins occurred over a 2 hour period. Activation of the regulated secretory pathway using ionomycin over the last hour resulted in a preferential increase in secretion of alpha- and gamma-caseins. Brefeldin A (BFA) inhibited protein secretion and synthesis in mammary cells in prolonged incubations. An examination of short-term treatments with BFA on 32P incorporation into the caseins revealed a differential effect of BFA in which the drug inhibited phosphorylation of beta- and gamma- but not alpha-caseins. These results suggest that phosphorylation of alpha-casein normally occurs in Golgi cisternae whereas that of beta- and gamma-caseins occurs in the trans-Golgi network. Phosphorylation of specific secretory proteins may, therefore, occur in different Golgi compartments.

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3

Markoska, Tatijana, Todor Vasiljevic, and Thom Huppertz. "Unravelling Conformational Aspects of Milk Protein Structure—Contributions from Nuclear Magnetic Resonance Studies." Foods 9, no. 8 (August 16, 2020): 1128. http://dx.doi.org/10.3390/foods9081128.

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Changes in the molecular structure and association of milk proteins lead to many desirable (under controlled conditions) or undesirable characteristics of dairy products. Several methods have been used to study the structure of milk proteins and changes therein in different environments. Whey proteins are an excellent model for secondary structure studies using circular dichroism (CD), Fourier-transform infrared spectroscopy (FTIR) and tertiary structure studies using X-ray crystallography and nuclear magnetic resonance (NMR). However, caseins, the most abundant protein class in milk, are far more difficult to characterize. The tertiary structure of caseins cannot be observed by X-ray crystallography due to the inability to crystallize caseins. However, NMR is an appropriate approach for structural elucidation. Thus far, NMR was applied on specific peptides of individual caseins of the molecules including phosphoserine centers and colloidal calcium phosphate. The literature focuses on these parts of the molecule due to its importance in building the sub-unit particles involving individual caseins and calcium phosphate nanoclusters. This review focuses on present structural studies of milk proteins using NMR and their importance in dairy processing.

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4

Pepe, Giacomo, Gian Carlo Tenore, Raffaella Mastrocinque, Paola Stusio, and Pietro Campiglia. "Potential Anticarcinogenic Peptides from Bovine Milk." Journal of Amino Acids 2013 (February 26, 2013): 1–7. http://dx.doi.org/10.1155/2013/939804.

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Bovine milk possesses a protein system constituted by two major families of proteins: caseins (insoluble) and whey proteins (soluble). Caseins (αS1, αS2, β, and κ) are the predominant phosphoproteins in the milk of ruminants, accounting for about 80% of total protein, while the whey proteins, representing approximately 20% of milk protein fraction, include β-lactoglobulin, α-lactalbumin, immunoglobulins, bovine serum albumin, bovine lactoferrin, and lactoperoxidase, together with other minor components. Different bioactivities have been associated with these proteins. In many cases, caseins and whey proteins act as precursors of bioactive peptides that are released, in the body, by enzymatic proteolysis during gastrointestinal digestion or during food processing. The biologically active peptides are of particular interest in food science and nutrition because they have been shown to play physiological roles, including opioid-like features, as well as immunomodulant, antihypertensive, antimicrobial, antiviral, and antioxidant activities. In recent years, research has focused its attention on the ability of these molecules to provide a prevention against the development of cancer. This paper presents an overview of antitumor activity of caseins and whey proteins and derived peptides.

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5

Wilson, Michael, Daniel M. Mulvihill, William J. Donnelly та Brian P. Gill. "Surface active properties at the air–water interface of β-casein and its fragments derived by plasmin proteolysis". Journal of Dairy Research 56, № 3 (травень 1989): 487–94. http://dx.doi.org/10.1017/s0022029900028971.

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Summaryβ-Casein, was enzymically modified by incubation with plasmin to yield γ-caseins and proteose peptones. Whole γ-, γ1-, γ2/γ3-caseins and whole proteose peptone (pp) were isolated from the hydrolysate mixture. The time dependence of surface tension at the air-water interface of solutions of β-casein and its plasmin derived fragments, at concentrations of 10−1 to 10−4% (w/v) protein, pH 7.0, was determined, at 25 °C, using a drop volume apparatus. The ranking of the proteins with respect to rate of reduction of surface tension, during the first rate determining step, at 10-2% (w/v) protein, was γ2/γ3 ≫ pp > whole γ- > γ1- > β-casein. The ranking of the proteins with respect to surface pressures attained after 40 min (π40) was concentration dependent. γ2/γ3-Caseins were found to be very surface active, decreasing surface tension rapidly and giving a high π40. γ1 Casein decreased surface activity somewhat faster than β-casein, but generally reached a lower π40. Whole γ-casein reflected the properties of both γ1 and γ2/γ3-caseins. Proteose peptone was found to decrease surface tension rapidly during the initial rate determining step; it gave a relatively high π40 at a bulk phase concentration of 10−3% (w/v) protein, but, it was the least surface active protein at 10−1 and 10−2% (w/v) protein.

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6

Feng, Ping, Christophe Fuerer, and Adrienne McMahon. "Quantification of Whey Protein Content in Infant Formulas by Sodium Dodecyl Sulfate-Capillary Gel Electrophoresis (SDS-CGE): Single-Laboratory Validation, First Action 2016.15." Journal of AOAC INTERNATIONAL 100, no. 2 (March 1, 2017): 510–21. http://dx.doi.org/10.5740/jaoacint.16-0344.

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Abstract Protein separation by sodium dodecyl sulfate-capillary gel electrophoresis, followed by UV absorption at 220 nm, allows for the quantification of major proteins in raw milk. In processed dairy samples such as skim milk powder (SMP) and infant formulas, signals from individual proteins are less resolved, but caseins still migrate as one family between two groups of whey proteins. In the first group, α-lactalbumin and β-lactoglobulin migrate as two distinct peaks. Lactosylated adducts show delayed migration times and interfere with peak separation, but both native and modified forms as well as other low-MW whey proteins still elute before the caseins. The second group contains high-MW whey proteins (including bovine serum albumin, lactoferrin, and immunoglobulins) and elutes after the caseins. Caseins and whey proteins can thus be considered two distinct nonoverlapping families whose ratio can be established based on integrated areas without the need for a calibration curve. Because mass-to-area response factors for whey proteins and caseins are different, an area correction factor was determined from experimental measurement using SMP. Method performance assessed on five infant formulas showed RSDs of 0.2–1.2% (within day) and 0.5–1.1% (multiple days), with average recoveries between 97.4 and 106.4% of added whey protein. Forty-three different infant formulas and milk powders were analyzed. Of the 41 samples with manufacturer claims, the measured whey protein content was in close agreement with declared values, falling within 5% of the declared value in 76% of samples and within 10% in 95% of samples.

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7

Singh, Harjinder, Albert Flynn, and Patrick F. Fox. "Binding of zinc to bovine and human milk proteins." Journal of Dairy Research 56, no. 2 (May 1989): 235–48. http://dx.doi.org/10.1017/s0022029900026455.

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SummaryZn binding by whole bovine and human casein and by purified bovine caseins and whey proteins was investigated by equilibrium dialysis. Bovine αs1 casein had the greatest Zn-binding capacity (˜ 11 atoms Zn/mol). Protein aggregation was observed as Zn concentration was increased and- the protein precipitated at a free Zn concentration of 1·7 mM. Zn binding increased with increasing pH in the range 5·4–7·0 and decreased with increasing ionic strength. Competition between Zn and Ca was observed for binding to αs1-casein indicating common binding sites for these two metals. Bovine β-casein bound up to 8 atoms Zn/ mol and precipitated at a free Zn concentration of ˜ 2·5 mM, while K-casein bound 1–2 atoms Zn/mol. Whole bovine and human casein bound 5–8 atoms Zn/mol and precipitated at a free Zn concentration of ˜ 2·0 mM. Scatchard plots for Zn binding to caseins showed upward convexity, possibly due to Zn-induced association of caseins. Apparent average association constants (K¯app) for all caseins were similar (log K¯app 3·0–3·2). Enzymic dephosphorylation of αs1- or whole bovine casein markedly reduced, but did not eliminate, Zn binding. Thus, phosphoserine residues appeared to be the primary Zn-binding sites in caseins. With the exception of bovine serum albumin. which bound over 8 atoms Zn/mol, the bovine whey proteins, β-lactoglobulin, α-lactalbumin and lactotransferrin, had little capacity for Zn binding.

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8

Pelmuş, Rodica Ştefania, Cristina Lazăr, M. L. Palade, Mariana Stancu, C. M. Rotar, and M. A. Gras. "Study on milk composition and milk protein distribution in Romanian Holstein cattle." Archiva Zootechnica 23, no. 1 (June 1, 2020): 13–21. http://dx.doi.org/10.2478/azibna-2020-0002.

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AbstractThe aim of this study was to determine milk quality indices as well as the milk protein composition in Romanian Holstein cattle raised under the conditions of experimental farm of INCDBNA-IBNA. The study was carried out on 22 milk samples. The types of different milk proteins were identified by SDS-PAGE technique. Sampling day and milk chemical composition were performed during the milking period of studied cattle. The quality indices were breed-specific for protein (3.38%) and higher for fat (4.39%).Milk proteins analysis of Romanian Holstein cattle separated by SDS-PAGE electrophoresis showed the presence of four major caseins (αs1-, αs2-, β- and k-casein) and two whey proteins (β-lactoglobulin, α-lactalbumin). The caseins accounted 77.28% of the total milk proteins, while the major proteins (β-lactoglobulin, α-lactalbumin) from the whey represented 22.72% of the total proteins. αs1-casein + αs2-casein had a higher expression (36.01%) followed by β-casein (31.45%), β-lactoglobulin (18.16%), k-casein (9.82%) and α-lactalbumin (4.56%). The most of milk samples was characterized by a medium expression level of both caseins and whey proteins

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9

Adechian, Solange, Michèle Balage, Didier Remond, Carole Migné, Annie Quignard-Boulangé, Agnès Marset-Baglieri, Sylvie Rousset, et al. "Protein feeding pattern, casein feeding, or milk-soluble protein feeding did not change the evolution of body composition during a short-term weight loss program." American Journal of Physiology-Endocrinology and Metabolism 303, no. 8 (October 15, 2012): E973—E982. http://dx.doi.org/10.1152/ajpendo.00285.2012.

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Studies have shown that timing of protein intake, leucine content, and speed of digestion significantly affect postprandial protein utilization. Our aim was to determine if one can spare lean body mass during energy restriction by varying the quality and the timing of protein intake. Obese volunteers followed a 6-wk restricted energy diet. Four groups were compared: casein pulse, casein spread, milk-soluble protein (MSP, = whey) pulse, and MSP spread ( n = 10–11 per group). In casein groups, caseins were the only protein source; it was MSP in MSP groups. Proteins were distributed in four meals per day in the proportion 8:80:4:8% in the pulse groups; it was 25:25:25:25% in the spread groups. We measured weight, body composition, nitrogen balance, 3-methylhistidine excretion, perception of hunger, plasma parameters, adipose tissue metabolism, and whole body protein metabolism. Volunteers lost 7.5 ± 0.4 kg of weight, 5.1 ± 0.2 kg of fat, and 2.2 ± 0.2 kg of lean mass, with no difference between groups. In adipose tissue, cell size and mRNA expression of various genes were reduced with no difference between groups. Hunger perception was also never different between groups. In the last week, due to a higher inhibition of protein degradation and despite a lower stimulation of protein synthesis, postprandial balance between whole body protein synthesis and degradation was better with caseins than with MSP. It seems likely that the positive effect of caseins on protein balance occurred only at the end of the experiment.

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10

WARD, BRENT R., SIMON J. GODDARD, MARY-ANN AUGUSTIN, and IAN R. McKINNON. "EDTA-induced dissociation of casein micelles and its effect on foaming properties of milk." Journal of Dairy Research 64, no. 4 (November 1997): 495–504. http://dx.doi.org/10.1017/s0022029997002367.

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The effects of addition of EDTA on the dissociation of caseins and foaming properties of milks (100 g solids/l) reconstituted from skim milk powders given a low-heat (72°C for 30 s) or high-heat (85°C for 30 min) treatment during powder manufacture were determined. The EDTA-induced dissociation of caseins was independent of heat treatment but in high-heat milk was accompanied by release of denatured whey proteins. EDTA changed the proportions of individual caseins in the supernatant. EDTA addition improved both foam overrun and foam stability of low- and high-heat milks. The increase in serum protein on addition of EDTA contributed to the improvement in foaming properties of milks by increasing the availability of the proteins for formation of the air–water interface.

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11

Lorient, Denis, Brigitte Closs, and Jean Luc Courthaudon. "Surface properties of the bovine casein components: relationships between structure and foaming properties." Journal of Dairy Research 56, no. 3 (May 1989): 495–502. http://dx.doi.org/10.1017/s0022029900028983.

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SummaryIn order to optimize the use of caseins as surfactants, the surface tension, foaming capacity and stability were measured as a function of pH, ionic strength, protein concentration and polarity (modified by covalent binding of carbohydrates). We found that the caseins differ in their behaviour at the air/water interface with β-casein showing the greatest ability to decrease surface tension and to produce foams, due probably to its amphipathic structure. In experiments carried out at pH values close to pI, with low ionic strength and constant solubility (optimal conditions for foam formation), we observed a high surface hydrophobicity, a good accessibility and flexibility of peptidic side chains (evaluated by proteolysis), and a high foaming capacity parallelled by increased surface pressure. Foam stability of caseins was low compared to those of globular proteins such as β lactoglobulin.

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12

Duanis-Assaf, Danielle, Eli Kenan, Ronit Sionov, Doron Steinberg та Moshe Shemesh. "Proteolytic Activity of Bacillus subtilis upon κ-Casein Undermines Its “Caries-Safe” Effect". Microorganisms 8, № 2 (6 лютого 2020): 221. http://dx.doi.org/10.3390/microorganisms8020221.

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Milk is believed to be a relatively “caries-safe” food. This belief relies on the fact that caseins, which constitute around 80% of milk’s protein content, were found to inhibit the adhesion of Streptococcus mutans to enamel and, therefore, decrease biofilm formation. While S. mutans is considered a leading cause of dental disorders, Bacillus subtilis is a non-pathogenic foodborne bacterium, frequently contaminating milk and its products. This study aimed to investigate the effects of dairy-associated foodborne bacteria such as B. subtilis on biofilm formation by S. mutans in the presence of casein proteins. Our results indicate that there is a significant decrease in total biofilm formation by S. mutans exposed to a casein protein mixture in a mono-species culture, whereas, in the co-culture with B. subtilis, an inhibitory effect of the caseins mixture on S. mutans biofilm formation was observed. Proteolytic activity analysis suggested that B. subtilis is capable of breaking down milk proteins, especially κ-casein, which enables biofilm formation by S. mutans in the presence of milk caseins. Therefore, these findings may challenge the assumption that milk is “caries-safe”, especially in a complex microbial environment.

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13

Díaz-Carrillo, E., A. Muñoz-Serrano, A. Alonso-Moraga та J. M. Serradilla-Manrique. "Near Infrared Calibrations for Goat's Milk Components: Protein, Total Casein, αs-, β- and k-caseins, Fat and Lactose". Journal of Near Infrared Spectroscopy 1, № 3 (червень 1993): 141–46. http://dx.doi.org/10.1255/jnirs.17.

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A fast and inexpensive method to quantify the main constituents of goat's milk using near infrared (NIR) spectroscopy, is proposed. Since the efficiency of milk-to-cheese transformation depends on the total amount of casein, as well as on the relative proportions of the different types of caseins, it is desirable to quantify not only protein, fat and lactose, as is normally done routinely in the cheese industry and milk recording schemes, but also total casein, αs-, β- and k-caseins. Quantities of these main components have been measured in milk samples of three Spanish breeds of goats, using traditional chemical, electrophoretical and densitometric laboratory methods in order to produce NIR calibrations for total protein, total casein, casein fractions (αs-, β- and k-caseins), fat and lactose. Low standard errors and high coefficients of determinations have been obtained for the calibrations and validations. Goat's milk spectra are described, and the contribution of different components to the observed pattern is discussed. Due to the low cost, facility and rapidity of the analyses after the spectrophotometer has been calibrated for each milk component, the use of near infrared spectroscopy becomes a suitable tool to analyse large numbers of samples and, therefore, very suitable for dairy goat recording schemes.

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14

Salelles, Léa, Juliane Floury, and Steven Le Feunteun. "Pepsin activity as a function of pH and digestion time on caseins and egg white proteins under static in vitro conditions." Food & Function 12, no. 24 (2021): 12468–78. http://dx.doi.org/10.1039/d1fo02453a.

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15

Candreva, Angela María, Paola Lorena Smaldini, Renata Curciarello, Ana Cauerhff, Carlos Alberto Fossati, Guillermo Horacio Docena, and Silvana Petruccelli. "Cross-Reactivity Between the Soybean Protein P34 and Bovine Caseins." Allergy, Asthma & Immunology Research 7, no. 1 (2015): 60. http://dx.doi.org/10.4168/aair.2015.7.1.60.

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16

Green, M. R. "Identification of human milk kappa-casein on polyacrylamide gels by differential staining with Ethyl-Stains-all and chymosin sensitivity." Journal of Histochemistry & Cytochemistry 34, no. 2 (February 1986): 147–50. http://dx.doi.org/10.1177/34.2.2418097.

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Ethyl-Stains-all (ESA), a cationic carbocyanine dye that stains phosphorylated, sialylated, and unmodified proteins differentially, was used to stain a human casein fraction enriched for its kappa-casein-like characteristics. The staining properties and chymosin sensitivity of this fraction were compared with those of human milk and bovine casein proteins. Phosphorylated human and bovine beta caseins stained blue with ESA. The sialic acid-containing bovine kappa-casein stained blue-green. The human kappa-like fraction was enriched for a protein that stained blue-green with ESA. Both bovine kappa-casein and the human blue-green-staining protein were susceptible to chymosin digestion at lower concentrations of chymosin than that required for digestion of beta-caseins. In each case, following chymosin digestion, a green-staining peptide of lower molecular weight replaced the original protein and para-kappa-casein was formed. Identification of human kappa-casein on SDS-polyacrylamide gels was based on its differential staining with ESA and chymosin sensitivity with respect to beta-casein.

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17

Brown, Joanna R., Andrew J. R. Law, and Christopher H. Knight. "Changes in casein composition of goats' milk during the course of lactation: physiological inferences and technological implications." Journal of Dairy Research 62, no. 3 (August 1995): 431–39. http://dx.doi.org/10.1017/s0022029900031137.

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SummaryFive British Saanen goats were milk sampled during the first 39 weeks of lactation to determine changes in casein composition. Caseins were separated by anion- and cation-exchange FPLC to determine the relative amounts of the individual caseins. Acid, alkaline and SDS-PAGE were used to determine possible genetic polymorphisms and observe any lactational changes. Total casein nitrogen was determined using a micro-Kjeldahl method and this allowed the concentrations of individual caseins to be calculated. The milk of one animal, which had the deduced genotype αs1-CnAB, showed higher concentrations of both total and αs1-casein. The remainder of the group were either heterozygous αs1-CnBE or, more probably, homozygous αs1-CnE and produced milk of a generally lower protein concentration. Both FPLC and PAGE results showed that the relative amounts and concentrations of αs2-casein decreased with stage of lactation, consistent with its susceptibility to proteolysis. The relative amounts of the breakdown products of plasmin attack on β-casein, γ-caseins, were highly negatively correlated with milk yield (r = –0·942, P < 0·001) in the declining phase of lactation, reflecting the gradual involution of the gland at this time. The relative amount of κ-casein increased by ∼ 50% after peak lactation and its concentration almost doubled near the end of lactation. These compositional changes may alter the processing qualities of goats' milk in relation to cheese production.

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18

Cichy, Aleksandra, Alicja Dratwa-Chałupnik, Weronika Medeńska, and Małgorzata Ożgo. "Preparing mare milk sample for proteomic analysis using two-dimensional electrophoresis." ANIMAL SCIENCE AND GENETICS 18, no. 3 (September 30, 2022): 11–24. http://dx.doi.org/10.5604/01.3001.0015.9831.

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There is no universal method to prepare physiological fluids for 2-DE proteomic analysis. Furthermore, interspecies differences in milk composition require the formulation of a species-specific sample preparation procedure. The study was carried out on mare's milk which was prepared for 2-DE in four different methods: the first sample (M1) was defatted, sample M2 was defatted and after casein precipitation, sample M3 was sample M2 after reduction of high molecular proteins and sample M4 was desalted sample M3. The milk samples prepared in different methods were separated by 1-DE and 2-DE. The obtained gels were analysed qualitatively and quantitatively. Furthermore, selected protein spots were identified by MALDI-TOF MS. Analysis of 1-DE and 2-DE gel images indicated that the optimal procedure for preparing mare milk samples for 2-DE and identification of proteins by MS is a method based on defatting and precipitation of caseins. The preparation of mare's milk samples by defatting and then precipitation of caseins is enough to obtain an optimal 2-DE separation for identification of proteins of this body fluid. The method of caseins precipitation should be improved in order to reduce the proportion of these high-abundance protein in milk samples which could increase in the identification of low-abundance proteins in mare's milk.

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19

Yong, Yie Hui, and E. Allen Foegeding. "Caseins: Utilizing Molecular Chaperone Properties to Control Protein Aggregation in Foods." Journal of Agricultural and Food Chemistry 58, no. 2 (January 27, 2010): 685–93. http://dx.doi.org/10.1021/jf903072g.

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20

BELLOQUE, JOSEFINA, and MERCEDES RAMOS. "Determination of the casein content in bovine milk by 31P-NMR." Journal of Dairy Research 69, no. 3 (August 2002): 411–18. http://dx.doi.org/10.1017/s0022029902005630.

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The relative proportion of caseins to total protein is a parameter that can be used to control the protein quality in standardised milk, an increasing tendency in dairy industries. 31P-NMR was used to analyse the casein content of milk, by the quantitation of the area under the resonances belonging to SerP, and using methylenediphosphonic acid as internal standard. This procedure yielded good results, as similar values of caseins were obtained from N Kjeldahl and NMR analysis for slightly heated milk samples. Heating at 95 °C for 15 min did not alter the casein content results. Casein content of raw, pasteurised and UHT milks (25·6±1·4, 26·4±1·8, 25·5±1·6 g casein/l milk, respectively), obtained by NMR, were not significantly different, giving an average of 25·8±1·6 g casein/l for bulk liquid milk. This work concluded that 31P-NMR could be used as an alternative method to determine casein in raw, pasteurised, dry and UHT milks.

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21

Lefèvre, Christophe M., Julie A. Sharp, and Kevin R. Nicholas. "Characterisation of monotreme caseins reveals lineage-specific expansion of an ancestral casein locus in mammals." Reproduction, Fertility and Development 21, no. 8 (2009): 1015. http://dx.doi.org/10.1071/rd09083.

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Using a milk-cell cDNA sequencing approach we characterised milk-protein sequences from two monotreme species, platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus) and found a full set of caseins and casein variants. The genomic organisation of the platypus casein locus is compared with other mammalian genomes, including the marsupial opossum and several eutherians. Physical linkage of casein genes has been seen in the casein loci of all mammalian genomes examined and we confirm that this is also observed in platypus. However, we show that a recent duplication of β-casein occurred in the monotreme lineage, as opposed to more ancient duplications of α-casein in the eutherian lineage, while marsupials possess only single copies of α- and β-caseins. Despite this variability, the close proximity of the main α- and β-casein genes in an inverted tail–tail orientation and the relative orientation of the more distant kappa-casein genes are similar in all mammalian genome sequences so far available. Overall, the conservation of the genomic organisation of the caseins indicates the early, pre-monotreme development of the fundamental role of caseins during lactation. In contrast, the lineage-specific gene duplications that have occurred within the casein locus of monotremes and eutherians but not marsupials, which may have lost part of the ancestral casein locus, emphasises the independent selection on milk provision strategies to the young, most likely linked to different developmental strategies. The monotremes therefore provide insight into the ancestral drivers for lactation and how these have adapted in different lineages.

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22

Macedo Mota, Lucio Flavio, Sara Pegolo, Vittoria Bisutti, Giovanni Bittante, and Alessio Cecchinato. "Genomic Analysis of Milk Protein Fractions in Brown Swiss Cattle." Animals 10, no. 2 (February 20, 2020): 336. http://dx.doi.org/10.3390/ani10020336.

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Depending on whether milk protein fractions are evaluated qualitatively or quantitatively, different genetic outcomes may emerge. In this study, we compared the genetic parameters for the major milk protein fractions—caseins (αS1-, αS2-, β-, and к-CN), and whey proteins (β-lactoglobulin, β-LG; α-lactalbumin, α-LA)—estimated using the multi-trait genomic best linear unbiased prediction method and expressed variously as milk content (g/100g milk), percentage of milk nitrogen (%N) and daily yield per cow (g/d). The results showed that the genetic parameter estimates varied according to how the milk protein fractions were expressed. Heritability estimates for the caseins and whey protein fractions expressed as daily yields were lower than when they were expressed as proportions and contents, revealing important differences in genetic outcomes. The proportion and the content of β-CN were negatively correlated with the proportions and contents of αS1-CN, αS2-CN, and к-CN, while the daily yield of β–CN was negatively correlated with the daily yields of αS1-CN and αS2-CN. The Spearman’s rank correlations and the coincidence rates between the various predicted genomic breeding values (GEBV) for the milk protein fractions expressed in different ways indicated that these differences had a significant effect on the ranking of the animals. The results suggest that the way milk protein fractions are expressed has implications for breeding programs aimed at improving milk nutritional and technological characteristics.

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23

Panthi, Ram R., Francesca Bot, and James A. O’Mahony. "Influence of Glycomacropeptide on Rehydration Characteristics of Micellar Casein Concentrate Powder." Foods 10, no. 8 (August 23, 2021): 1960. http://dx.doi.org/10.3390/foods10081960.

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Glycomacropeptide (GMP) shows potential for enhancing the rehydration properties of high-protein dairy powders due to its hydrophilic nature. This study involved formulating micellar casein concentrate (MCC) solutions (8.6% final protein content) with 0, 10, and 20% GMP as a percentage of total protein, and investigated the physicochemical and rehydration properties of the resultant freeze-dried powders (P-MCC-0G, P-MCC-10G, and P-MCC-20G, respectively). The surface charges of caseins in the control MCC and 10 or 20% GMP blended solutions were −25.8, −29.6, and −31.5 mV, respectively. Tablets prepared from P-MCC-10G or P-MCC-20G powders displayed enhanced wettability with contact angle values of 80.6° and 79.5°, respectively, compared with 85.5° for P-MCC-0G. Moreover, blending of GMP with MCC resulted in faster disintegration of powder particles during rehydration (i.e., dispersibility) compared to P-MCC-0G. Faster and more extensive release of caseins from powder particles into solution was evident with the increasing proportion of GMP, with the majority of GMP released within the first 15 min of rehydration. The results of this study will contribute to further development of formulation science for achieving enhanced solubility characteristics of high-protein dairy powder ingredients, such as MCC.

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24

DUNCAN, Jennifer S., and Robert D. BURGOYNE. "Characterization of the effects of Ca2+ depletion on the synthesis, phosphorylation and secretion of caseins in lactating mammary epithelial cells." Biochemical Journal 317, no. 2 (July 15, 1996): 487–93. http://dx.doi.org/10.1042/bj3170487.

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We have examined the effects of depleting lumenal Ca2+ on the synthesis, phosphorylation and secretion of caseins in lactating mouse mammary cells by using inhibitors of the endoplasmic reticulum Ca2+-ATPase or the ionophore ionomycin in the absence of external Ca2+. Treatment with these drugs resulted in a transient increase in the cytosolic Ca2+ concentration due to Ca2+ mobilization. Protein synthesis over a 1 h period was substantially inhibited by Ca2+ depletion, but in a pulse–chase protocol secretion of pre-synthesized proteins was unaffected by Ca2+ depletion. Analysis of polysome profiles showed that Ca2+ depletion resulted in a loss in polysomes, consistent with an inhibition of initiation of protein synthesis. Neither treatment with Ca2+-ATPase inhibitors to deplete endoplasmic reticulum Ca2+ nor treatment with ionomycin/EGTA had any effect on an early phase of phosphorylation of α- or β/γ-caseins, but Ca2+ depletion resulted in a decrease in a late phase of casein phosphorylation. These results indicate that lumenal Ca2+ is required to maintain protein synthesis in lactating mammary cells but is not required for protein secretion, and that Ca2+ accumulation in the Golgi cisternae is required for a late but not for an early phase of casein phosphorylation.

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25

Ledesma-Martínez, Edgar, Itzen Aguíñiga-Sánchez, Benny Weiss-Steider, Ana Rocío Rivera-Martínez, and Edelmiro Santiago-Osorio. "Casein and Peptides Derived from Casein as Antileukaemic Agents." Journal of Oncology 2019 (September 8, 2019): 1–14. http://dx.doi.org/10.1155/2019/8150967.

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Milk is a heterogeneous lacteal secretion mixture of numerous components that exhibit a wide variety of chemical and functional activities. Casein, the main protein in milk, is composed of α-, β-, and κ-caseins, each of which is important for nutritional value and for promoting the release of cytokines, also are linked to the regulation of haematopoiesis and immune response and inhibit the proliferation and induce the differentiation of leukaemia cells. It has been shown that the digestive process of caseins leads to the release of bioactive peptides that are involved in the regulation of blood pressure and the inhibition or activation of the immune response by serving as agonists or antagonists of opioid receptors, thus controlling the expression of genes that exert epigenetic control. Later, they bind to opioid receptor, block nuclear factor κ-beta, increase the redox potential, and reduce oxidative stress and the pro-inflammatory agents that favour an antioxidant and anti-inflammatory environment. Therefore, the bioactive peptides of casein could be compounds with antileukaemia potential. This review provides a summary of current knowledge about caseins and casein peptides on the immune system as well as their roles in the natural defence against the development of leukaemia and as relevant epigenetic regulators that can help eradicate leukaemia.

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26

Markoska, Tatijana. "Influence of pH and solids content on heat-induced changes in structural arrangements of proteins in milk." Mljekarstvo 71, no. 2 (March 16, 2021): 95–102. http://dx.doi.org/10.15567/mljekarstvo.2021.0202.

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Concentrated milk systems can be unstable during heat treatment. In this work, we studied the structural changes in the proteins in skim milk (9, 17 and 25 % solids) as a result of pH adjustment to pH 7.5 and heating at 75, 85, 95 100, 110 and 121 °C by Fourier transform infrared spectroscopy (FTIR) and SDS-PAGE. The pH adjustment to 7.5 resulted in some dissociation of caseins to serum, predominately in the 9 % total solids samples. Furthermore, pH adjustment resulted in an increase in random structures at all concentration levels, due to protein unfolding. Heat treatment affected greatly the protein composition in the serum phase and induced structural modifications. All milk samples when heated to 110 °C exhibited loss of serum β-LG, α-LA and caseins (mainly κ-casein) as a result of heat induced aggregation. The intensity of aggregation increased with concentration factor. The trend appeared similar at 121 °C but with larger aggregates. As a concentration factor increased, covalent bonds among newly formed structures appeared to prevail.

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27

Pitois, Emmanuelle, Thierry Chardot, and Jean Claude Meunier. "Overphosphorylation of Milk Caseins by a Recombinant Protein Kinase CK2 Catalytic Subunit." Journal of Agricultural and Food Chemistry 47, no. 10 (October 1999): 3996–4002. http://dx.doi.org/10.1021/jf990145t.

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28

Ma, Fengtao, Jingya Wei, Liyuan Hao, Qiang Shan, Hongyang Li, Duo Gao, Yuhang Jin, and Peng Sun. "Bioactive Proteins and their Physiological Functions in Milk." Current Protein & Peptide Science 20, no. 7 (June 27, 2019): 759–65. http://dx.doi.org/10.2174/1389203720666190125104532.

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Milk is the basic food for infants and newborn animals, providing a rich source of proteins, carbohydrates, minerals, and vitamins. Milk also provides nourishment for people of all ages due to its abundant nutrients, and it is used in the manufacture of numerous health-related products. Milk contains caseins and whey proteins as the two major protein classes. Caseins fall into four major types known as αs1-, αs2-, β- and κ-casein, whereas whey proteins comprise a mixture of globular proteins including β-lactoglobulin, α-lactalbumin, serum albumin, lactoferrin, and other bioactivators. The various biological activities of these proteins are involved in preventing and treating numerous nutritional, physiological and metabolic diseases. This article reviews the bioactivities and functions of milk proteins, which may shed light on future application of milk bioactive substances.

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29

Yamaguchi, Shotaro, and Masaaki Yokoe. "A Novel Protein-Deamidating Enzyme fromChryseobacterium proteolyticum sp. nov., a Newly Isolated Bacterium from Soil." Applied and Environmental Microbiology 66, no. 8 (August 1, 2000): 3337–43. http://dx.doi.org/10.1128/aem.66.8.3337-3343.2000.

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ABSTRACT A novel protein-deamidating enzyme, which has potential for industrial applications, was purified from the culture supernatant ofChryseobacterium proteolyticum strain 9670Tisolated from rice field soil in Tsukuba, Japan. The deamidating activities on carboxybenzoxy (Cbz)-Gln-Gly and caseins and protease activity were produced synchronously by the isolate. Both deamidating activities were eluted as identical peaks separated from several proteases by phenyl-Sepharose chromatography of the culture supernatant. The enzyme catalyzed the deamidation of native caseins with no protease and transglutaminase activities. Phenotypic characterization and DNA analyses of the isolate were performed to determine its taxonomy. Physiological and biochemical characteristics, 16S rRNA gene sequence analysis, and DNA-DNA relatedness data indicated that the isolate should be placed as a new species belonging to the genus Chryseobacterium. The isolate showed no growth on MacConkey agar and produced acid from sucrose. The levels of DNA-DNA relatedness between the isolate and other related strains were less than 17%. The name Chryseobacterium proteolyticum is proposed for the new species; strain 9670 is the type strain (=FERM P-17664).

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30

SORENSEN, ANNETTE, D. DONALD MUIR, and CHRISTOPHER H. KNIGHT. "Thrice-daily milking throughout lactation maintains epithelial integrity and thereby improves milk protein quality." Journal of Dairy Research 68, no. 1 (February 2001): 15–25. http://dx.doi.org/10.1017/s0022029900004593.

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Cows managed for extended lactations of 16 months duration were milked on a half-udder basis twice or thrice daily, commencing in lactation week 9. Mammary epithelial integrity (assessed by milk sodium[ratio ]potassium ratio) was greater in the half-udder which was milked thrice daily. This difference was evident throughout the lactation but became greater after week 41. Milk protein composition was assessed during late lactation (52±3 weeks). Casein number (casein as a proportion of total protein) was significantly higher in half-udders milked thrice daily, as were the relative amounts of α- and β-caseins, whilst those of κ- and γ-caseins were reduced. Two days of inverted milking frequency (i.e. thrice-milked udder halves now milked twice, and vice versa) only partly reversed these differences. We concluded that thrice-daily milking will help to prevent or ameliorate the usual decline in milk processing quality associated with late lactation. Part of this effect is due simply to reduced exposure to proteolytic enzymes as a result of decreased storage time in the udder, but part is due to a better maintenance of epithelial tight junction integrity as lactation advances, which restricts leakage of proteolytic enzymes from serum into milk.

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31

Hellebois, Thierry, Jennyfer Fortuin, Claire Gaiani, and Christos Soukoulis. "Impact of Flaxseed Gums on the Colloidal Changes and In Vitro Digestibility of Milk Proteins." Foods 11, no. 24 (December 18, 2022): 4096. http://dx.doi.org/10.3390/foods11244096.

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Flaxseed (Linum usitatissimum L.) mucilage is one of the most studied plant seed gums in terms of its techno-functional and health-promoting properties. Nonetheless, the interplay of flaxseed gum (FG) with other food biopolymers, such as milk proteins, under in vitro digestion conditions remains underexplored. The aim of the present work was to investigate the colloidal interplay between flaxseed gum (golden or brown) and milk proteins (sodium caseinate or whey protein isolate) under simulated in vitro digestion conditions and its relationship with the attained in vitro protein digestibility. The presence of flaxseed gum in the milk protein food models and in the oral food boluses obtained was associated with the occurrence of segregative microphase separation. Flaxseed gum exhibited a prominent role in controlling the acid-mediated protein aggregation phenomena, particularly in the sodium caseinate gastric chymes. The addition of FG in the food models was associated with a higher amount of intact total caseins and β-lactoglobulin at the end of the gastric processing step. Monitoring of the intestinal processing step revealed a very advanced cleavage of the whey proteins (>98%) and caseins (>90%). The degree of the milk protein hydrolysis achieved at the end of the intestinal processing was significantly higher in the systems containing flaxseed gum (i.e., 59–62%) than their gum-free protein counterparts (i.e., 46–47%). It was postulated that the electrostatic milk protein complexation capacity and, to a lesser extent, the thickening effect of flaxseed gum influenced the in vitro digestibility of the milk proteins.

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32

Chen, Chun-Chi, Liang-Yu Chen, Der-Sheng Chan, Bang-Yuan Chen, Hsien-Wei Tseng, and Jung-Feng Hsieh. "Influence of Microbial Transglutaminase on Physicochemical and Cross-Linking Characteristics of Individual Caseins." Molecules 25, no. 17 (September 2, 2020): 3992. http://dx.doi.org/10.3390/molecules25173992.

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The effects of microbial transglutaminase (MTGase) cross-linking on the physicochemical characteristics of individual caseins were investigated. MTGase was used to modify three major individual caseins, namely, κ-casein (κ-CN), αS-casein (αS-CN) and β-casein (β-CN). The SDS-PAGE analysis revealed that MTGase-induced cross-linking occurred during the reaction and that some components with high molecular weights (>130 kDa) were formed from the individual proteins κ-CN, αS-CN and β-CN. Scanning electron microscopy (SEM) and particle size analysis respectively demonstrated that the κ-CN, αS-CN and β-CN particle diameters and protein microstructures were larger and polymerized after MTGase cross-linking. The polymerized κ-CN (~749.9 nm) was smaller than that of β-CN (~7909.3 nm) and αS-CN (~7909.3 nm). The enzyme kinetics results showed KM values of 3.04 × 10−6, 2.37 × 10−4 and 8.90 × 10−3 M for κ-CN, αS-CN and β-CN, respectively, and, furthermore, kcat values of 5.17 × 10−4, 1.92 × 10−3 and 4.76 × 10−2 1/s, for κ-CN, αS-CN and β-CN, respectively. Our results revealed that the cross-linking of β-CN catalyzed by MTGase was faster than that of αS-CN or κ-CN. Overall, the polymers that formed in the individual caseins in the presence of MTGase presented a higher molecular weight and larger particles.

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33

RÄIHÄ, NIELS C. R. "Protein Quality in Feeding the Normal Infant: Do Whey-Predominant Formulas Offer Nutritional Advantages?" Pediatrics 76, no. 2 (August 1, 1985): 329. http://dx.doi.org/10.1542/peds.76.2.329.

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To the Editor.— In a recently published paper, I have discussed milk proteins and the question of protein requirement of the normal infant.1 This paper was reviewed in a summary in the same supplement of Pediatrics.2 Because this summary contains some statements that are not in complete agreement with those in the original paper, I would like to clarify a few points concerning the quality of protein in infant formula. The whey proteins make up the majority, about 70% of proteins in human milk whereas caseins are the primary proteins of bovine milk.

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34

Bayat-Sarmadi, Mahasti, Rachel Maliénou-Ngassa, Claudine Puissant, and Louis-Marie Houdebine. "6-Dimethyl amino purine and 2-amino purine inhibit the induction of expresion of milk protein genes by prolactin." Bioscience Reports 12, no. 3 (June 1, 1992): 189–97. http://dx.doi.org/10.1007/bf01121788.

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Two protein kinase-inhibitors, 6-dimethyl amino purine and 2-amino purine inhibited induction of β-casein synthesis by prolactin when added to the culture medium of rabbit mammary explant and cells. The accumulation of the mRNA for αs1- and β-caseins and for whey acidic protein did not take place in the presence of the inhibitors whereas β-actin mRNA concentration was not altered. In the same experimental conditions, H7, an inhibitor of protein kinase C and, to a lower extent, of protein kinase A did not prevent prolactin from acting. These data suggest for the first time that specific protein kinases are involved in the transduction of the prolactin signal to milk protein genes.

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35

Daher, Dahlia, Barbara Deracinois, Philippe Courcoux, Alain Baniel, Sylvie Chollet, Rénato Froidevaux, and Christophe Flahaut. "Sensopeptidomic Kinetic Approach Combined with Decision Trees and Random Forests to Study the Bitterness during Enzymatic Hydrolysis Kinetics of Micellar Caseins." Foods 10, no. 6 (June 7, 2021): 1312. http://dx.doi.org/10.3390/foods10061312.

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Protein hydrolysates are, in general, mixtures of amino acids and small peptides able to supply the body with the constituent elements of proteins in a directly assimilable form. They are therefore characterised as products with high nutritional value. However, hydrolysed proteins display an unpleasant bitter taste and possible off-flavours which limit the field of their nutrition applications. The successful identification and characterisation of bitter protein hydrolysates and, more precisely, the peptides responsible for this unpleasant taste are essential for nutritional research. Due to the large number of peptides generated during hydrolysis, there is an urgent need to develop methods in order to rapidly characterise the bitterness of protein hydrolysates. In this article, two enzymatic hydrolysis kinetics of micellar milk caseins were performed for 9 h. For both kinetics, the optimal time to obtain a hydrolysate with appreciable organoleptic qualities is 5 h. Then, the influence of the presence or absence of peptides and their intensity over time compared to the different sensory characteristics of hydrolysates was studied using heat maps, random forests and regression trees. A total of 22 peptides formed during the enzymatic proteolysis of micellar caseins and influencing the bitterness the most were identified. These methods represent simple and efficient tools to identify the peptides susceptibly responsible for bitterness intensity and predict the main sensory feature of micellar casein enzymatic hydrolysates.

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36

Kern, Loïc, Olivier Fabre, Joël Scher та Jeremy Petit. "Chemical fractionation of caseins by differential precipitation: influence of pH, calcium addition, protein concentration and temperature on the depletion in α‐ and β‐caseins". International Journal of Food Science & Technology 55, № 2 (4 серпня 2019): 542–52. http://dx.doi.org/10.1111/ijfs.14283.

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37

Li, Nan, and Qixin Zhong. "Improving rehydration properties of spray-dried milk protein isolates by supplementing soluble caseins." Food Research International 150 (December 2021): 110770. http://dx.doi.org/10.1016/j.foodres.2021.110770.

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38

GALAZKA, VANDA B., and ERIC DICKINSON. "SURFACE PROPERTIES OF PROTEIN LAYERS ADSORBED FROM MIXTURES OF GELATIN WITH VARIOUS CASEINS." Journal of Texture Studies 26, no. 4 (November 1995): 401–9. http://dx.doi.org/10.1111/j.1745-4603.1995.tb00980.x.

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39

Power, Orla M., Mark A. Fenelon, James A. O'Mahony, and Noel A. McCarthy. "Dephosphorylation of caseins in milk protein concentrate alters their interactions with sodium hexametaphosphate." Food Chemistry 271 (January 2019): 136–41. http://dx.doi.org/10.1016/j.foodchem.2018.07.086.

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40

Dubert-Ferrandon, Alix, Keshaven Niranjan, and Alistair S. Grandison. "A novel technique for differentiation of proteins in the development of acid gel structure from control and heat treated milk using confocal scanning laser microscopy." Journal of Dairy Research 73, no. 4 (July 12, 2006): 423–30. http://dx.doi.org/10.1017/s0022029906001907.

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The incorporation of caseins and whey proteins into acid gels produced from unheated and heat treated skimmed milk was studied by confocal scanning laser microscopy (CSLM) using fluorescent labelled proteins. Bovine casein micelles were labelled using Alexa Fluor 594, while whey proteins were labelled using Alexa Fluor 488. Samples of the labelled protein solutions were introduced into aliquots of pasteurised skim milk, and skim milk heated to 90 °C for 2 min and 95 °C for 8 min. The milk was acidified at 40 °C to a final pH of 4·4 using 20 g glucono-delta-lactone/l (GDL). The formation of gels was observed with CSLM at two wavelengths (488 nm and 594 nm), and also by visual and rheological methods. In the control milk, as pH decreased distinct casein aggregates appeared, and as further pH reduction occurred, the whey proteins could be seen to coat the casein aggregates. With the heated milks, the gel structure was formed of continuous strands consisting of both casein and whey protein. The formation of the gel network was correlated with an increase in the elastic modulus for all three treatments, in relation to the severity of heat treatment. This model system allows the separate observation of the caseins and whey proteins, and the study of the interactions between the two protein fractions during the formation of the acid gel structure, on a real-time basis. The system could therefore be a valuable tool in the study of structure formation in yoghurt and other dairy protein systems.

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41

Torres, Isabel Celigueta, Gema Nieto, Tommy Nylander, Adam Cohen Simonsen, Alexander Tolkach, and Richard Ipsen. "Effect of homogenisation in formation of thermally induced aggregates in a non- and low- fat milk model system with microparticulated whey proteins." Journal of Dairy Research 84, no. 2 (May 2017): 229–38. http://dx.doi.org/10.1017/s002202991700019x.

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The objective of the research presented in this paper was to investigate how different characteristics of whey protein microparticles (MWP) added to milk as fat replacers influence intermolecular interactions occurring with other milk proteins during homogenisation and heating. These interactions are responsible for the formation of heat-induced aggregates that influence the texture and sensory characteristics of the final product. The formation of heat-induced complexes was studied in non- and low-fat milk model systems, where microparticulated whey protein (MWP) was used as fat replacer. Five MWP types with different particle characteristics were utilised and three heat treatments used: 85 °C for 15 min, 90 °C for 5 min and 95 °C for 2 min. Surface characteristics of the protein aggregates were expressed as the number of available thiol groups and the surface net charge. Intermolecular interactions involved in the formation of protein aggregates were studied by polyacrylamide gel electrophoresis and the final complexes visualised by darkfield microscopy. Homogenisation of non-fat milk systems led to partial adsorption of caseins onto microparticles, independently of the type of microparticle. On the contrary, homogenisation of low-fat milk resulted in preferential adsorption of caseins onto fat globules, rather than onto microparticles. Further heating of the milk, led to the formation of heat induced complexes with different sizes and characteristics depending on the type of MWP and the presence or not of fat. The results highlight the importance of controlling homogenisation and heat processing in yoghurt manufacture in order to induce desired changes in the surface reactivity of the microparticles and thereby promote effective protein interactions.

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42

Manson, William, Thomas Carolan, and W. Douglas Annan. "Products of the heat-promoted reaction between urea and the protein fraction of bovine milk." Journal of Dairy Research 52, no. 3 (August 1985): 401–7. http://dx.doi.org/10.1017/s0022029900024304.

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SUMMARYEnzymic digests of samples of heated skimmed milk were found to contain small amounts of S-carbamyl-L-cysteine. This material was concluded to have arisen from reaction of a cysteinyl residue in βlactoglobulin (β-lg) with cyanate derived from the native urea of bovine milk. After heating at 75 or 90 °C for 20 min skimmed milk contained 0·009 and 0·029 μmol/ml respectively of protein-bound S-carbamyl-cysteine. Evaporated milk contained 0·058 μmol/ml. The S-carbamylcysteine contents of samples of β-lg heated under similar conditions in equimolar 0·17 mM-KCNO at pH 6·6 were 0·016 and 0·062 μmol/ml respectively. At 60 °C no formation of S-carbamyl-cysteine was detected. Samples of evaporated milk and skimmed milk which had been heated for 20 min at 60, 75 or 90 °C were examined, after acid hydrolysis, for the presence of homocitrulline. None was found. Similarly αs1- and β-caseins heated at 60 and 75 °C in 4 mM-urea at pH 6·6 yielded no homocitrulline, but after treatment at 90 °C for 20 min αs1-casein contained 68 μg/g and β-casein contained 73 μg/g protein-bound homocitrulline. This was concluded to have been the product of reaction of cyanate and ε-amino groupings of lysyl residues of the caseins. The relative importance of carbamylation involving ε-amino groups or sulphydryl groups in milk is discussed.

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43

LEE, SUNG JE, and JOHN W. SHERBON. "Chemical changes in bovine milk fat globule membrane caused by heat treatment and homogenization of whole milk." Journal of Dairy Research 69, no. 4 (November 2002): 555–67. http://dx.doi.org/10.1017/s002202990200571x.

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The effects of heat treatment and homogenization of whole milk on chemical changes in the milk fat globule membrane (MFGM) were investigated. Heating at 80 °C for 3–18 min caused an incorporation of whey proteins, especially β-lactoglobulin (β-lg), into MFGM, thus increasing the protein content of the membrane and decreasing the lipid. SDS-PAGE showed that membrane glycoproteins, such as PAS-6 and PAS-7, had disappeared or were weakly stained in the gel due to heating of the milk. Heating also decreased free sulphydryl (SH) groups in the MFGM and increased disulphide (SS) groups, suggesting that incorporation of β-lg might be due to association with membrane proteins via disulphide bonds. In contrast, homogenization caused an adsorption of caseins to the MFGM but no binding of whey proteins to the MFGM without heating. Binding of caseins and whey proteins and loss of membrane proteins were not significantly different between milk samples that were homogenized before and after heating. Viscosity of whole milk was increased when milk was treated with both homogenization and heating.

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44

Jensen, Hanne B., Nina A. Poulsen, Hanne S. Møller, Allan Stensballe, and Lotte B. Larsen. "Comparative proteomic analysis of casein and whey as prepared by chymosin-induced separation, isoelectric precipitation or ultracentrifugation." Journal of Dairy Research 79, no. 4 (September 24, 2012): 451–58. http://dx.doi.org/10.1017/s0022029912000404.

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Fractionation of bovine milk was performed using chymosin-induced separation, isoelectric precipitation or ultracentrifugation as separation techniques prior to gel-based proteomic analysis. This approach allowed for comparative display and identification of proteins partitioned into casein and whey, respectively. Initially, three different staining methods (silver staining, colloidal Coomassie Blue G-250 or fluorescent Flamingo Pink staining) for two-dimensional gel electrophoresis (2-DGE) analysis were compared for their suitability as staining agent, especially in relation to their suitability to reveal differences in the casein fractions. Fluorescent staining proved to be the most appropriate for this purpose, giving a high sensitivity, and using this staining method, characteristic 2-DGE fingerprints were obtained for each casein and whey fraction from each separation method. A number of protein spots in both casein and whey fractions varied with separation method and these spots were subsequently identified using tandem mass spectrometry (MS). In rennet casein, proteolytic fragmentation of caseins (αs1-, αs2,-, β- and κ-) was identified as a result of chymosin hydrolysis, whereas the 2-DGE profile of acid and ultracentrifuged casein was dominated by the presence of multiple isoforms of κ-caseins. Furthermore, casein remnants were identified in milk serum after ultracentrifugation. This study shows that gel-based proteomic analysis is suitable for characterisation of subtle variations in protein composition of milk fractions that occur as a consequence of different milk fractionation strategies.

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45

Panteli, Maria, Evangelia Zoidou, and Golfo Moatsou. "Comparative study of the paracasein fraction of two ewe's milk cheese varieties." Journal of Dairy Research 82, no. 4 (June 19, 2015): 491–98. http://dx.doi.org/10.1017/s0022029915000254.

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The aim of the present work was to assess the characteristics of the paracasein of two ewe's milk cheese varieties using various concentrations of urea and EDTA to solubilise caseins and calcium. The solubilised paracasein elements were evaluated by means of RP-HPLC and AAS. For this purpose cheeses with different physical and biochemical characteristics, i.e. Feta (53·1% moisture and pH 4·32) and Graviera Kritis (33·2% moisture and pH 5·54) were analysed. Soluble calcium of Feta was 71% of total calcium much higher than the 25% in Graviera. Treatment with 4 m urea fully solubilised Feta paracasein, whereas 6 m urea was needed to solubilise caseins from Graviera. Caseins were released from both cheeses by 100 mm EDTA. Solubilisation of paracasein induced by urea or EDTA was not significantly affected (P < 0·05) by the type of cheese. Similarly to urea, EDTA induced significantly (P < 0·05) lower solubilisation of αs1-casein in Graviera than in Feta, based on αs1-cn/β-cn ratio. A great part of calcium in both cheeses was solubilised by 50 mm EDTA while the release of casein was poor, confirming the important role of types of interactions other than protein-calcium bonds in the paracasein network. Hydrophobic interactions, hydrogen bonds and electrostatic attractions, contributed substantially to the paracasein stability of both cheese types. The interactions of αs1-casein with calcium played a more significant role in Graviera cheese than in Feta. Finally, the present study demonstrated that the profile of bonds and interactions within the cheese paracasein network was dynamicly configured by the conditions of cheese manufacture.

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46

LÉONARD, M., H. T. HUNG, G. ROBITAILLE, and E. BLOCK. "EFFECT OF A SUSTAINED-RELEASE FORM OF SOMATOTROPIN ON THE PROFILE OF MILK PROTEINS AND FATTY ACIDS DURING A FULL LACTATION." Canadian Journal of Animal Science 70, no. 3 (September 1, 1990): 811–19. http://dx.doi.org/10.4141/cjas90-100.

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Twenty-three Holstein cows received one injection of recombinant bovine somatotropin (bST) every 28 d at one of four doses: 0, 320, 640, or 960 mg 28 d−1. All injections started in early lactation and continued until the cows were dried-off. Composites of AM and PM milkings were analyzed for fatty acids by gas-liquid chromatography, for percent milk protein by infrared analysis and for casein by electrophoresis. For the 0, 320, 640, 960 mg cow−1 28 d−1 bST treatment groups, average ± SE milk protein percents for the entire lactation were 3.24 ± 0.08%, 3.25 ± 0.07%, 3.31 ± 0.08% and 3.24 ± 0.07%, respectively (P > 0.05); average milk caseins were 2.59 ± 0.07%, 2.61 ± 0.06%, 2.60 ± 0.07% and 2.57 ± 0.06%, respectively (P > 0.05), and average whey proteins were 0.65 ± 0.03%, 0.64 ± 0.03%, 0.71 ± 0.03% and 0.67 ± 0.03%, respectively (P > 0.05). No effect of bST was observed on milk fatty acids and protein at any dose or stage of lactation. Concentrations of αs-, β- and K-casein were not affected by bST treatment (P > 0.05). Fat percentages were 3.78 ± 0.21%, 3.91 ± 0.19%, 3.76 ± 0.19% and 4.02 ± 0.16% for the 0, 320, 640 and 960 mg 28 d−1 treatment (P > 0.05). Milk fatty acids were not affected by bST treatment (P > 0.05). Short chain fatty acids and medium chain fatty acids were decreased (P < 0.05) with progressing lactation while long chain fatty acids were increased in late lactation (P < 0.05). Key words: Somatotropin, composition of milk, caseins, milk fatty acids

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47

Lamure, Alain, Jean-François Pommert, Alain Klaebe, Colette Lacabanne, and Jean-Jacques Perie. "Effect of polyphosphate binding on the chain dynamic of caseins: investigation by differential scanning calorimetry and thermally stimulated currents." Journal of Dairy Research 55, no. 3 (August 1988): 401–12. http://dx.doi.org/10.1017/s002202990002865x.

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SummarySamples of caseins having different Ca contents as used in cheese processing were analysed by techniques using differential scanning calorimetry and thermally stimulated currents (TSC) before and after treatment with Na poly-phosphate, a food additive used in the manufacture of processed cheese. These techniques revealed structural changes induced by the salt, and the different types of water molecules associated with the protein are evident. This characterization is in agreement with results obtained by other techniques, particularly X-ray diffraction of proteins. Transmission electron microscopy of the same samples confirmed that the changes observed by TSC were associated with an unravelling of the protein.

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48

Ménard, Olivia, Marie-Hélène Famelart, Amélie Deglaire, Yann Le Gouar, Sylvie Guérin, Charles-Henri Malbert, and Didier Dupont. "Gastric Emptying and Dynamic In Vitro Digestion of Drinkable Yogurts: Effect of Viscosity and Composition." Nutrients 10, no. 9 (September 14, 2018): 1308. http://dx.doi.org/10.3390/nu10091308.

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Gastric emptying of food is mainly driven by the caloric concentration, the rheological properties of the chyme, and the physical state (liquid/solid) of food once in the stomach. The present work investigated: (1) The effect of the composition and the viscosity of drinkable yogurts on gastric emptying in pigs, and (2) the behavior of yogurts during dynamic in vitro digestion. Three isocaloric liquid yogurts were manufactured: Two enriched in protein and fiber showing either a low (LV) or high (HV) viscosity, one control enriched in sugar and starch (CT). They were labelled with 99mTc-sulfur colloid and given to pigs (n = 11) to determine gastric emptying pattern by gamma scintigraphy. Then dynamic in vitro digestion of the yogurts was done using the parameters of gastric emptying determined in vivo. Gastric emptying half-times were significantly longer for LV than CT, whereas HV exhibited an intermediate behavior. In vitro gastric digestion showed a quick hydrolysis of caseins, whereas whey proteins were more resistant in the stomach particularly for LV and HV. During the intestinal phase, both whey proteins and caseins were almost fully hydrolyzed. Viscosity was shown to affect the behavior of yogurt in the small intestine.

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49

Gasparini, Alessandra, Sofie Buhler, Andrea Faccini, Stefano Sforza та Tullia Tedeschi. "Thermally-Induced Lactosylation of Whey Proteins: Identification and Synthesis of Lactosylated β-lactoglobulin Epitope". Molecules 25, № 6 (12 березня 2020): 1294. http://dx.doi.org/10.3390/molecules25061294.

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The high temperatures used in the production of milk may induce modifications in proteins structure. Due to occurrence of the Maillard reaction, lactose binds lysine residues in proteins, affecting the nutritional value. Milk is also an important source of allergenic proteins (i.e., caseins, β-lactoglobulin and α-lactalbumin). Thus, this modification may also affect the allergenicity of these proteins. Focusing on milk whey proteins, a screening on different Ultra High Temperatures (UHT) and pasteurized milk samples was performed to identify lactosylation sites, in particular in protein known epitopes, and to verify the correlation between lactosylation and the harshness of the treatment. Whey proteins were extracted from milk samples after caseins precipitations at pH 4.6 and, after chymotryptic and tryptic in solution digestion, peptides were analysed by UPLC-MS and LTQ-Orbitrap. Results show the presence of lactosylated lysine residues in several known epitopes. Then, a β-lactoglobulin epitope was selected and synthesized by solid phase synthesis followed by in solution lactosylation, obtaining high reaction yields and purities. The synthesis of lactosylated allergenic epitopes, described here for the first time, is a useful tool for further studies on the technological impacts on food allergenicity.

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50

Gazi, Inge, and Thom Huppertz. "Influence of protein content and storage conditions on the solubility of caseins and whey proteins in milk protein concentrates." International Dairy Journal 46 (July 2015): 22–30. http://dx.doi.org/10.1016/j.idairyj.2014.09.009.

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