Presence Of Casein Research Articles

Lactobacilli counts in crop, ileum and caecum of growing broiler chickens fed on practical diets containing whole or dehulled sweet lupin (Lupinus angustifolius) seed meal

1. Four experiments with growing broiler chickens were carried out to study the effects of the inclusion in their diets of lupin (Lupinus angustifolius ) seed meal on E. coli and lactobacilli counts in crop, ileum and caeca at 3 or 4 weeks of age. 2. Diets were formulated to contain the same amounts of metabolisable energy (12.55 MJ/kg) and protein (210 g/kg). Raw whole (heat-untreated) or dehulled sweet (low in alkaloids) lupin seed meal (400 and 320 g/kg respectively) were used to prepare the lupin-based diets, whose protein content was completed with either defatted soyabean meal or casein. 3. Final body weight and food intake of chickens fed on whole lupin seed meal diets were lower than controls, but gain: food ratios were not different. However, birds given the diet with dehulled lupin seed meal had similar body weight, food intake and gain: food values as those of controls. 4. While E. coli counts were not affected, lactobacilli numbers were consistently increased compared to controls in all intestinal sections of chickens fed on the whole or dehulled lupin-based diets, irrespective of the age of the birds or the presence of soyabean meal or casein in the diet. The lactobacilli species isolated were: Lactobacillus fermentum, L. acidophilus, L. salivarius and L. brevis 5. The results suggest that the use of whole or dehulled sweet lupin seed meal in diets for growing broilers might enhance the growth of lactic acid-fermenting bacteria in the gut.

Extracellular proteases produced by the Quorn® myco-protein fungus Fusarium graminearum in batch and chemostat culture.

Fusarium graminearum was grown in batch and continuous (chemostat) culture on a glucose-mineral salts medium in the presence and absence of casein. In the absence of casein no protease activity was detected in the culture filtrate from either batch or chemostat culture. For batch cultures grown on medium containing casein, most of the proteolytic activity detected in the supernatant during exponential growth had an optimum at ca pH 5.0. However, as the cultures passed from late exponential into stationary phase, the pH profile of the protease activity broadened until most of it was in the alkaline pH region. For glucose-limited chemostat cultures grown on media containing casein, protease activity had a narrow pH optimum with maximum activity at pH 5.0. For all concentrations of casein examined, protease activity was greater in chemostat culture than in batch culture. Extracellular proteases from batch and chemostat cultures were purified by bacitracin-Sepharose affinity chromatography. At least seven proteins were purified from batch cultures but chemostat cultures contained only a single aspartic protease with a molecular mass of 40 kDa.

Milk-responsive atopic dermatitis is associated with a casein-specific lymphocyte response in adolescent and adult patients

Background: Specific T-cell responses to food antigens have been described in children with atopic dermatitis (AD). However, a subgroup of adolescent and adult patients still experiences food-responsive AD. Objective: This study was designed to evaluate lymphocyte responses to bovine casein in adult patients with AD. Methods: The stimulatory capacity of lipopolysaccharide-depleted bovine casein was tested in proliferation assays and in limiting dilution assays. Casein-specific T-cell clones (TCCs) were generated and characterized. Results: Higher proliferative responses to casein and modulation of cytokine receptors were observed in patients with milk-responsive AD compared with individuals without clinical reactions on milk ingestion. The results did not correlate with the amount of casein-specific IgE in the serum. The frequencies of T cells that grew in the presence of casein or house dust mite antigens were similar. Only 27% of CD4 + casein-specific TCCs from these patients, but the majority of house dust mite–specific TCCs, produced IL-4 on mitogen stimulation. Interferon-γ, on the other hand, was produced by the majority of TCCs with both specificities. Conclusion: A specific T-cell–mediated immune response to casein can be found in the blood of adolescent and adult patients with milk-related exacerbation of AD. In contrast to house dust mite–specific T cells, casein-specific T cells of adult patients who respond to cow's milk with worsening of AD produce little or no IL-4. (J Allergy Clin Immunol 1997;99:124-33.)

Determination of casein by square‐wave voltammetry using electrocatalytic reduction of nickel(II)

AbstractThe catalytic peak produced at −0.80 V (vs Ag/AgCl) by the presence of casein in the reduction of NIII on a dropping mercury electrode in sodium acetate medium was explored using square‐wave voltammetry (SWV). The effects of the electrochemical variables on SW voltammograms were studied and optimum operating conditions were established (10−2 M NiII, 1 M sodium acetate, pH 7.0 and temperature of 23° C). Good linearity between the SW voltammetric peak current and casein concentrations in the 0–128 mg L−1 range was obtained. An electrocatalytic method is proposed for the determination of casein with rapid and precise results (relative standard deviation of 5.2 %).

Biosynthesis of extracellular low-molecular-mass papain and trypsin inhibitors by Streptomyces sp. 22: effect of cultural conditions.

The production of extracellular inhibitors of papain and trypsin by Streptomyces sp. 22 was studied under different cultural conditions including complex and defined media, temperatures ranging from 18 degrees C to 37 degrees C and a variety of sole carbon and nitrogen sources. In complex nutritionally rich medium, maximal specific growth rates were obtained at 37 degrees C, whereas the highest specific production rates for both papain and trypsin inhibitors were registered at 18 degrees C. Studies on the effect of different carbon and nitrogen sources in defined media underline the importance of the nitrogen source as a strong regulator of the biosynthesis of both inhibitors. Enhanced formation of the inhibitory compounds occurred in the presence of casein. The dynamics of the formation of both inhibitors in defined media showed close association with growth. However, a partial separation of production phases for papain and trypsin inhibitors was observed in complex medium. The results imply differences in the regulation of biosynthesis of the two inhibitors.

Studies on Interactions between Phosphatidylcholine and Casein

The interactions between casein and either egg phosphatidylcholine or dipalmitoylphosphatidylcholine were studied using dynamic light scattering and fluorescence polarization. Casein was found not to adsorb to a suspension of phospholipid vesicles, but a stable complex was formed when casein and phospholipid were homogenized together to form the vesicles. The hydrodynamic thickness of the layer of casein associated with vesicles was close to twice that of the casein layer adsorbed to the surfaces of oil droplets in oil-in-water emulsions. The breakdown of incorporated casein molecules by trypsin caused aggregation or fusion of the vesicles, in contrast to the behavior of emulsions, which remain stable under such treatment. Changes in the fluorescence polarization demonstrated that the association of casein with DPPC vesicles made the lipid bilayer more rigid in its liquid crystalline state, but little difference was detected in the gel state. The topological response of the vesicles to temperature change was significantly modified by the presence of casein in the bilayer. The results suggest that the casein associated with the lipid bilayer is not simply adsorbed to the surface but penetrates deeper into the inner core of the bilayer, so that caseins appear to behave as transmembrane proteins

Isolation and characterization of plasminogen and plasmin from bovine milk

Abstract A procedure was developed for the isolation of plasminogen and plasmin from bovine milk. Pure undegraded plasminogen with N-terminal amino acid sequence and mobility in SDS-PAGE similar to plasminogen isolated from bovine blood was obtained. Additionally, the preparation contained the proteolytically modified midi-plasmin, consisting of kringle 4,5 and the light chain with an apparent molecular weight of 50 k Da in unreduced SDS-PAGE, and resulting in two bands of 30 and 26 k Da after reduction. Some 15% of the amino acid sequence of plasminogen/midi-plasmin isolated from milk was determined. The partial amino acid sequence was identical to that previously reported for plasminogen isolated from bovine blood (J. Schaller et al., (1985). Eur. J. Biochem., 149, 267–278), and to the bovine liver plasminogen cDNA sequence (L. Berglund et al., (1995). Int. Dairy J., 5, 593–603). Enzyme-linked immunosorbent assay (ELISA) and Western blotting experiments revealed that immunoreactive plasminogen was associated with acid-precipitated casein, rennet-coagulated casein and casein micelles. Some was found in acid whey and to a lesser extent in rennet whey. The amount of plasminogen associated with the milk fat globule membrane was very low and reflected the presence of casein. By Western blotting, immunoreactive plasminogen was found in zones with apparent molecular weights of 85, 80 and 50 k Da in unreduced gels. These hands may represent two plasminogen forms (85 and 80 k Da) and midi-plasmin/midi-plasminogen (50 k Da). The total concentration of plasminogen in bovine milk was estimated to 1.5 μg/mL.

Purification and characterization of casein kinase II from lactating rabbit mammary gland

1. 1. Highly purified 200 kDa casein kinase II from rabbit lactating mammary gland (MG-CK II) was obtained by means of a new purification procedure consisting of one phosphocellulose and three Mono Q steps. 2. 2. Its K m for ATP was 2.22 μM and 0.57 mg/ml and 0.13 mg/ml for partially dephosphorylated casein and phosvitin respectively. Stathmine was also suitable as substrate. 2-aminopurine and 6-dimethylaminopurine inhibited efficiently MG-CK II K i = 5 and 1 mM respectively). 3. 3. MG-CK II autophosphorylated on its α-, α '- and β-subunits. The β-subunit auto-phosporylation was enhanced in presence of exogenous substrate. Its modulation was highly dependent on ATP concentration. 4. 4. The effects of basic compounds which affected dramatically the phosphorylation of dephosphorylated casein in presence of various ATP concentrations were reported.

Casein and tyrosine kinase activities of developing chick embryo liver. Effect of triiodothyronine

Cytosol cAMP-independent quercetin-inhibited protein kinase of developing chick embryo liver was measured at three embryonic ages (days 12, 14 and 18) in the presence of casein and poly (Glu-Na, Tyr) 4:1 as substrates. In the early embryonic stages the tyrosine kinase was almost as active as casein kinase, but on day 18 the tyrosine phosphorylation was only 25% of the casein phosphorylation. Both kinase activities strongly increased by the end of embryonic development: 7-fold with casein and 2.6-fold with poly (Glu-Na, Tyr) 4:1. Triiodothyronine caused twice the stimulation of casein and tyrosine phosphorylation on day 12, but had no effect on day 18.

NMR relaxation measurements of sucrose in aqueous ethanol solutions

The molecular motion of sucrose in water/alcohol/sucrose/casein solutions was studied by 13C-NMR spin-lattice relaxation measurements. The results suggest that the conformation of sucrose is unaffected by concentration, temperature, or the presence of alcohol or casein. There is no evidence for the interaction of sucrose with either alcohol or protein. Changes in the hydrodynamic radius of sucrose from relaxation measurement using solution or water viscosities were inconclusive.

Casein, a powerful enhancer of the rate of plasminogen activation

Casein was found to be a potent accelerator of the rate of plasminogen activation by both tissue plasminogen activator (t-PA) and urokinase plasminogen activator (u-PA). The effect is measured by the increase in the rate of hydrolysis of the synthetic plasmin substrate, Spectrozyme PL, when the activating mixture contains casein. The effect on two chain human urokinase was studied in detail. Both bovine and human casein are effective; of the three principal fractions of bovine casein, α, β, and κ, the α fraction was found to be most effective. α-casein, immobilized on agarose, bound both u-PA and plasminogen to a significantly greater extent than did plain agarose, or agarose conjugated to irrelevant proteins. The enhancement of the rate of activation by u-PA was much larger when Glu-plasminogen, rather than Lys-plasminogen, was used. In the presence of casein, Glu-plasminogen was activated at the fast rate characteristic of Lys-plasminogen. Since the presence of casein did not result in the proteolytic conversion of the Glu to the Lys form, the effect is interpreted as a change in the conformation of Glu-plasminogen to that of the Lys form, by interaction with casein. Kinetic analysis of the time course of activation at varying Glu-plasminogen concentrations gave a 23-fold decrease in Km in the presence of casein. This, coupled with a 3.45-fold increase in kcat, resulted in an 80-fold increase in kcat/Km, i.e. in the overall efficiency of activation. Indirect evidence suggests that the effect may be related to the micellar structure of casein.

Effect of fermentation by lactic acid bacteria from soybean seeds on trypsin inhibitor (TI) activity

Lactobacillus plantarum, Streptococcus lactis, Leuconostoc lactis and Pediococcus halophilus constituted the lactic flora of soy-bean ( Glycine max ) seeds. Fermentation of soy-flour mixed with bengal gram ( Cicer arietinum ) flour for 18 h at 30°C resulted in a decrease in activity and yielded a fermented food ‘soy-dhokla’. L. plantarum from soybean showed potential in decreasing TI activity from soy-flour and nutrient medium amended with tripsin inhibitor (TI) during fermentation at 30°C for 18 h. All the lactic isolates from soybean showed hydrolysis of casein in presence of TI indicating presence of protease in them different from trypsin.

Characterization of the alpha and beta subunits of casein kinase 2 by far-UV CD spectroscopy.

Although Chou-Fasman calculations of the secondary structure of recombinant casein kinase 2 subunits alpha and beta suggest they have a similar overall conformation, circular dichroism (CD) studies show that substantial differences in the conformation of the two subunits exist. In addition, comparison of the far-UV CD spectrum of reconstituted CK-2 with the spectra of the subunits indicates that conformational changes occur in the backbone region upon association. Such changes may explain the increased enzyme activity of the holoenzyme relative to that of the alpha subunit itself. In contrast, no changes in the far-UV CD spectrum of the alpha subunit are observed in the presence of casein or the synthetic decapeptide substrate RRRDDDSDDD. Furthermore, the alpha-helical structure of the alpha subunit (but not the beta subunit) can be increased in the presence of stoichiometric amounts of heparin, presumably by its binding to the polylysine stretch at amino acid positions 74-77. Heat denaturation experiments (25-90 degrees C) support the notion that heparin may provide a local protective function. A similar but much larger effect was also observed in the presence of the beta subunit only, which supports previous suggestions of a protective function for this subunit. These results indicate that the protection provided by the beta subunit and the increased enzyme activity of the holoenzyme may arise, in part, from a stabilization of the conformation of the enzyme complex and an increase in alpha-helical content.

Benzaldehyde, Citral, and d-Limonene Flavor Perception in the Presence of Casein and Whey Proteins

The effect of sodium caseinate and whey protein concentrate on benzaldehyde, d-limonene, and citral flavor intensity was determined by quantitative descriptive analysis deviation from reference using a 12-member trained panel. The concentrations for the benzaldehyde, d-limonene, and citral flavor intensity references were 17.8, 53.0, and 19.8ppm, respectively. The concentration for both protein references was .25%. Flavored protein solutions were held for 17h at 6°C and contained benzaldehyde (17.8ppm), d-limonene (53ppm), or citral (19.8ppm) and 2.5% sucrose with 0, .125, .25, or .5% protein. Benzaldehyde flavor intensity declined as the whey protein concentrate concentration increased from 0 to .5%. There was no significant difference in benzaldehyde flavor intensity with casein compared with the reference. The d-limonene flavor intensity declined as the protein concentration increased. Panelists found no significant drop in citral flavor intensity with casein or whey protein. Decreased benzaldehyde and d-limonene flavor intensity in the presence of whey protein concentrate or casein may be due to nonpolar interactions (casein), interaction with nonpolar binding sites, cysteine-aldehyde condensation, or Schiff base formation (whey protein concentrate).

Effects of culture conditions on amylase production by some soil fungi

Twenty-one species of soil fungi have been screened for amylolytic activity. Six species designated as active enzyme producers were used in the experiments: Aspergillus flavus, Cladosporium herbarum, Cunninghamella echinulata, Fusarium culmorum, Paecilomyces divaricata, and Penicillium notatum. The results obtained revealed that, in most cases, enzyme production and dry weight yield of mycelium were not positively correlated. An incubation period of 8 days at 27°C and an initial pH range of 4–6 were most favourable for enzyme production by all fungi studied. A 1.5% concentration of soluble starch was the most suitable substrate for all the studied fungi although rice and corn flours appeared to be preferred by A. flavus, F. culmorum, P. divaricata and P. notatum. Ammonium nitrate at 0.5% concentration provided a suitable nitrogen source for all fungi although productivity by A. flavus and P. divaricata was enhanced by the presence of casein and urea. A C: N ratio of 3:1 was the most favourable for all fungi investigated. A concentration of 10 μg/L SrCl2 favoured productivity by all fungi. Preferential utilization of nutrients caused changes in pH towards alkalinity which repressed productivity. 21 Bodenpilz-Arten wurden auf ihre amylolytische Aktivität untersucht. 6 Arten waren aktive Enzymproduzenten und wurden weiter optimiert: Aspergillus flavus, Cladosporium herbarum, Cunninghamella echinulata, Fusarium culmorum, Paecilomyces divaricata und Penicillium notatum. Die Ergebnisse offenbarten, daß in der Mehrzahl der Fälle die Enzymproduktion und der Trockengewichtsertrag des Myzels nicht positiv korrelierten. Bei allen untersuchten Pilzen war für die Enzymproduktion eine Inkubationszeit von 8 Tagen bei 27°C und ein Start-pH-Wert von 4–6 am günstigsten. Eine Konzentration von 1,5% löslicher Stärke war am geeignetsten, Reis und Korngetreidemehl wurden von A. flavus, F. culmorum, P. divaricata und P. notatum vorgezogen. Ammoniumnitrat (0,5%) ist die günstigste N-Quelle, allerdings wurde bei A. flavus und P. divaricata durch Anwesenheit von Casein und Harnstoff die Produktivität erhöht. Ein C : N-Verhältnis von 3:1 war für alle Pilze am günstigsten. Bevorzugte Verwertung von Nährsubstrat verursacht eine pH-Veränderung zur Alkalität, welche die Produktivität erniedrigt.

Interactions between volatile and non-volatile compounds in the presence of water

The interactions between volatile aromas and non-volatile compounds were studied by two techniques coupled with gas chromatography. These two techniques (head-space analysis and sorption) show that there exist interactions which depend on the nature of the volatile and non-volatile compounds and on the water content: for instance, the activity coefficient (measured by head-space analysis) of acetone and ethyl acetate in solution at infinite dilution increases in the presence of glucose. The sorption of a mixture of six aroma substances (acetone, ethyl acetate, diacetyl, 2-propanol, n-hexanol and benzaldehyde) on carbohydrates (glucose, maltodextrin, starch and β-cyclodextrin) and on caseinate at pH 3, 7 and 9 varies with the water content. The quantity of pure acetone sorbed on the carbohydrate substrates is greater than the total quantity of the mixture of six volatile compounds sorbed. The carbohydrate substrates sorb a lower quantity of volatile compounds than caseinate. It can be supposed that hydrogen bonds exist between carbohydrates, water and aroma substances, and also that hydrophobic interactions occur in the presence of casein.

Bile acid activity in the presence of dietary fibres, casein, calcium, phospholipid, fatty acid and cholesterol: factorial experiments in vitro

Binding of 14C-deoxycholic acid (DCA) in the presence of all combinations of digested wheat bran, casein tryptic peptides, Ca 2+, lecithin, cholesterol and stearate, and of 14C-glycocholic acid in the presence of all combinations of pectin, Ca 2+ and casein tryptic peptides has been studied in vitro using membrane microseparation. The level of free DCA was significantly lowered by all components individually, except for cholesterol. Large first-order interactions involving DCA-bran were obtained with casein peptide and lecithin, and a number of higher-order interactions were significant. Greatest significant binding involving wheat bran was observed with DCA-bran-casein peptide-lecithin (51.7%), DCA-bran-Ca 2+-lecithin-stearate (45%), and DCA-bran-Ca 2+-lecithin (42.5%), compared with DCA-bran (27.5%). Glycocholic acid was significantly bound by casein peptide with a small significant interaction with Ca 2+, but was not bound by pectin. These results suggest that possible health benefits, which arise through binding of secondary bile acids by cereal fibre, may be enhanced by other dietary components.

Allergenicity of bovine casein. II: Casein and Its digestive enzyme hydrolysate‐induced lymphocyte proliferation and Mastocyte histamine accumulation in casein‐free mice

First generations of milk protein exempted mice (6–8 weeks old) were fed with casein at 100 mg per day. At 0, 2, 4, 6, 8, 12 and 20 weeks of feeding, a group of eight mice was sacrificed to recover spleen lymphocytes and intraperitoneal mastocytes. In vitro lymphocyte 3H‐thymidine incorporation in the presence of intact casein, peptic or peptic‐tryptic‐chymotryptic hydrolysate was significantly higher at eight and 12 weeks of feeding (p<0.05). The number of the sensitized mice increased from 39% in the control group to 61% in the experimental groups. The three antigens possessed a statistically equal capacity to stimulate lymphocyte proliferation. Measurements of plasma and culture supernatant IgG antibody production exhibited an elevated enzyme‐linked immunosorbent assay value starting from the eight week of casein feeding. Casein feeding also provoked histamine accumulation in the mastocytes which occured significantly after four weeks of feeding (p<0.001). The fact that the lymphocytes recognized not o...

Allergenicity of bovine casein. I: Specific lymphocyte proliferation and histamine accumulation in the mastocyte as a result of casein feeding in mice

The effects of feeding cow milk casein (100 mg per day) on allergic responses in mice were studied by observing 3H‐thymidine incorporation in lymphocytes and histamine release from peritoneal mastocytes. Lymphocytes cultured in the presence of casein showed proliferative activities as early as two weeks feeding up to the eighth week. This activity was not in agreement with either the positive cutaneous test or the antigenic histamine liberation. The total histamine contents in the mastocytes were found to increase from 3.2±1.9 nmol per 105 cells for the control group to 7.1 ±3.2; 6.2 ± 1.3; 6.7 ± 1.6 after four, six and eight weeks of feeding, respectively. These findings leads us to postulate that there were lymphocyte activations and mastocyte histamine accumulations as the results of intestinal permeability to casein‐derived molecules.

Decrease of Vanillin Flavor Perception in the Presence of Casein and Whey Proteins

The effect of sodium caseinate and whey protein concentrate on vanillin flavor intensity was determined by quantitative descriptive analysis deviation from reference. A 12-member trained panel marked a horizontal line to rate vanillin, sodium caseinate, and whey protein concentrate flavor intensities in vanillin-sodium caseinate or vanillin-whey protein concentrate solutions using vanillin (78.5ppm), sodium caseinate (.25%), or whey protein concentrate (.25%) references. The vanillin-sodium caseinate and vanillin-whey protein concentrate solutions contained 78.5ppm vanillin, 2.5% sucrose, and .125, .25, and .5% sodium caseinate or whey protein concentrate, which were held 17h at 6°C. The panel evaluated samples at room temperature and found that vanillin flavor intensity was moderately less than the reference for all sodium caseinate levels. As whey protein concentrate concentration increased from .125 to .5%, vanillin flavor decreased from moderately less than vanillin reference to much less than vanillin reference. This decrease in vanillin flavor intensity in the presence of sodium caseinate or whey protein concentrate may be due to cysteine-aldehyde condensation or Schiff base formation.