Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Casein

  • milk casein

  • Terms modified by Casein

  • casein diet
  • casein fraction
  • casein kinase
  • casein kinase i
  • casein micelle
  • casein zymography

  • Selected Abstracts


    The encapsulation in lipospheres and in liposomes was used with the aim of masking the bitterness of casein hydrolysates for dietetic of pharmaceutical purposes. Papain was used for preparing three casein hydrolysates, employing different temperatures and E:S ratios. The percentage of encapsulation of these preparations was measured by second derivative spectrophotometry (SDS). Lipid oxidation over a period of 60 days, was followed by quantifying the 2-thiobarbituric acid reactive substances (TBARS). Other analysis were performed for characterizing these vesicles, including the sensory evaluation and the measure of hydrophobicity. The results showed that these two encapsulation systems were equally efficient in reducing the hydrophobicity and the bitterness of casein hydrolysates. SDS was a useful tool in the characterization of these preparations. It is a quick and relatively low-cost method, and indicated that the encapsulation rate in lipospheres (65%) was higher than in liposomes (59%). The TBARS method revealed the chemical stability of these preparations over the period of study (60 days). [source]

    Inhibition of hydroxyapatite dissolution by whole casein: the effects of pH, protein concentration, calcium, and ionic strength

    Michele E. Barbour
    Formulating drinks with reduced erosive potential is one approach for reducing dental erosion. In this study, whole casein was added to citric acid solutions representative of soft drinks, and the hydroxyapatite dissolution rate was assessed. Adding 0.02% (w/v) casein to acid solutions significantly reduced the hydroxyapatite dissolution rate by 51 4% at pH values of 2.80, 3.00, 3.20, 3.40, and 3.60, although the baseline dissolution rates of course varied as a function of pH. The protein concentration [0.002, 0.02, and 0.2% (w/v) casein] had no significant effect on dissolution inhibition. Adding both casein and calcium to citric acid resulted in a further reduction in the dissolution rate at low and intermediate calcium concentrations (5 and 10 mM) but not at higher calcium concentrations (20 and 50 mM). Ionic strength had no significant impact on the efficacy of casein. Casein also significantly reduced the hydroxyapatite dissolution rate when the hydroxyapatite was coated with a salivary pellicle. The reduction in dissolution rate is ascribed to firmly adsorbed casein on the hydroxyapatite surface, which stabilizes the crystal surface and inhibits ion detachment. [source]

    The Effect of Protein Particle Size Reduction on the Physical Properties of CO2 -Precipitated Casein Films

    Kirsten L. Dangaran
    ABSTRACT:, Casein precipitated with high pressure-CO2 (CO2CAS) has unique properties compared to commercial acid-precipitated casein. CO2CAS is less water-soluble and films made from it are less susceptible to high humidity environments; however, the films are also opaque and hazy. The appearance of CO2CAS films is important especially if applied as a food coating. To improve the appearance properties, the particle size of CO2CAS film plasticized with glycerol was reduced. The effect of protein particle size reduction on tensile properties, water vapor permeability (WVP), and gloss was studied using ASTM methodology. As particle size of the CO2CAS was reduced from 126 ,m to 111 ,m, tensile strength and modulus of the films increased, while WVP decreased. With the same particle reduction, gloss increased from 55.3 gloss units on average to 73 gloss units, but films were still hazy. With a particle size less than 86 ,m, CO2CAS films were glossy and transparent, however, tensile strength decreased and WVP increased. Depending on desired application, the properties of CO2CAS films can be optimized by changing particle size. [source]

    Effect of Ultra-high Temperature Treatment on the Enzymatic Cross-linking of Micellar Casein and Sodium Caseinate by Transglutaminase

    M.P. Bnisch
    ABSTRACT: It was found that ultra-high temperature (UHT) treatment of sodium caseinate and native whey protein-depleted micellar casein drastically increases the protein polymerization effect of an enzymatic treatment by microbial transglutaminase (TG). As a result the concentration of the isopeptide ,-(,-glutamyl)lysine was increased significantly in UHT-treated micellar casein solutions after TG incubation compared with the unheated casein solution. Sodium caseinate was more susceptible to the cross-linking reaction as compared with the native casein micelles. The results demonstrate that the protein structure significantly affects the TG cross-linking reaction. The effect of an UHT treatment was considered to be related to a better TG accessibility due to a more open casein micelle structure and to the inactivation of a TG inhibitor substance. The results demonstrate that an unidentified component in the natural milk serum inhibits the TG reaction. The thermal inactivation of a TG inhibitor is the dominant effect explaining the improved cross-linking of UHT-treated casein micelles as well as sodium caseinate. [source]

    Casein Hydrolysate Fractions Act as Emulsifiers in Process Cheese

    H.S. Kwak
    ABSTRACT: Degrees of hydrolysis and emulsifying activity of casein hydrolysates were the highest at 4 h hydrolysis. The oil-off values of the mixture of hydrolysate (H) or supernatant (S) and traditional emulsifier (T) were not significantly different from the control made with traditional emulsifier, except for S + T = 3:1. Two other samples made with hydrolysate or supernatant only (H or S) showed higher oil-off value than the others (p < 0.05). In flavor property, no difference was found between samples made with traditional emulsifier and those made with the mixture of hydrolysate or supernatant at the ratio of 3 to 1. Therefore, these results indicated that a mixture of the hydrolysate or supernatant and traditional emulsifier might replace a traditional emulsifier in process cheese manufacturing. [source]

    Determination of the phosphorylation level and deamidation susceptibility of equine ,-casein

    Jean-Michel Girardet Dr.
    Abstract ,-Casein was isolated from Haflinger mare's milk by RP-HPLC, and displayed microheterogeneity by urea-electrophoresis and 2-DE probably due to a variable degree of phosphorylation. To investigate the degree of phosphorylation, the primary structure of equine ,-casein was determined by tryptic hydrolysis and MS of peptides released and by MS of the protein treated by alkaline phosphatase. The molecular mass found for the apo-form of Haflinger mare's ,-casein (25,514 3,Da) was close to the theoretical mass of the reported sequence (GenBank,AAG43954) modified by insertion of a region (residues,27,34) encoded by an exon sometimes out-spliced (25,511.40,Da). Hence, the ,-casein isolated from Haflinger mare's milk corresponded to a variant of 226,amino acid residues. The latter was composed by highly multi-phosphorylated isoforms with three to seven phosphate groups, and pIs, determined by 2-DE, ranging from 4.74 to 5.30. Moreover, the equine ,-casein was able to deamidate spontaneously, at the level of Asn in the potential deamidation motif 135Asn-Gly136. Approximately 80% of the protein was deamidated after 96,h of incubation under physiological conditions. [source]

    Micellization of casein- graft -dextran copolymer prepared through Maillard reaction

    BIOPOLYMERS, Issue 1 2006
    Xiaoyun Pan
    Abstract Casein is almost insoluble at around pH 4.6, which is its isoelectric point (pI). Grafting copolymer, casein- g -dextran, was prepared through the Amadori rearrangement of the Maillard reaction. The copolymer has a reversible pH sensitive property: micellization at the pI of casein forming a casein core and dextran shell structure and dissociation when pH differs from the pI. The micelles produced at pH 4.6 have a spherical shape and their size is dependent on the Maillard reaction: reaction time, molar ratio of casein to dextran, and molecular weight of dextran used. Typically, the hydrodynamic diameter of the micelles is about 100 nm and the critical micelle concentration is about 10 mg/L. The micelles are very stable in aqueous solution and can be stored as lyophiled powder. The micelles are able to encapsulate hydrophobic compounds such as pyrene. 2005 Wiley Periodicals, Inc. Biopolymers 81: 29,38, 2006 This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at [source]

    Fractionation of Caseins by Anion-exchange Chromatography Using Food-grade Buffers

    K.N. Turhan
    ABSTRACT : Caseins prepared by microfiltration of bovine skim milk were fractionated using anion-exchange chromatography. Laser densitometry of electrophoresis gels was shown to be sufficiently quantitative to perform accurate mass balance calculations detailing the fate of each casein fraction. L-cysteine was successfully used as a reducing agent instead of traditional toxic agents, such as dithiothreitol or ,-mercaptoethanol, enabling development of the first food-grade buffer system for casein fractionation. More salt was required for elution of the casein fractions having a greater charge: ,s -casein > ,-casein > ,-casein. Increasing flow rate decreased the extent of separation. Use of smaller beads was suggested as a method to maintain separation at increased flow rate. [source]

    Novel MRI and fluorescent probes responsive to the Factor XIII transglutaminase activity

    Lorenzo Tei
    Abstract Transglutaminases, including factor XIII and tissue transglutaminase, participate in multiple extracellular processes associated with remodeling of the extracellular matrix during wound repair, blood clotting, tumor progression and fibrosis of ischemic injuries. The aim of this work was to evaluate a novel substrate analog for transglutaminase optimized by molecular modeling calculations (DCCP16), which can serve for molecular imaging of transglutaminase activity by magnetic resonance imaging and by near-infrared imaging. Experimental data showed covalent binding of Gd,DCCP16 and DCCP16-IRIS Blue to human clots, to basement membrane components and to casein in purified systems as well as in three-dimensional multicellular spheroids. In vivo, DCCP16 showed enhancement with a prolonged retention in clots and tumors, demonstrating the ability to detect both factor XIII and tissue transglutaminase mediated covalent binding of the contrast material. Copyright 2010 John Wiley & Sons, Ltd. [source]

    Microchip isoelectric focusing with monolithic immobilized pH gradient materials for proteins separation

    ELECTROPHORESIS, Issue 23 2009
    Yu Liang
    Abstract Monolithic immobilized pH gradient (M-IPG) materials were prepared in microchannles by photoinitiated polymerization of acrylamide, glycidylmethacrylate and Bis, followed by the attachment of focused Ampholine onto the surface of porous monoliths via epoxide groups. With M-IPG materials as matrix, FITC-labeled ribonuclease B, myoglobin and ,-casein were well separated by microchip isoelectric focusing (,CIEF) without carrier amphocytes (CAs) added in the buffer. Both chemical and pressure mobilization were applied to drive focused zones for LIF detection. Our experimental results showed that pressure mobilization was preferable with neglectable band broadening, and good peak shape and high detection sensitivity were obtained. All these results demonstrate that ,CIEF with M-IPG materials is not only an efficient mode for protein enrichment and separation but also attractive to couple with other CE modes to achieve multi-dimensional separation or MS for further identification, without the interference of mobile CAs. [source]

    Reproducible protein analysis by CE using linear polyacrylamide-coated capillaries and hydrochloric acid rinsing

    ELECTROPHORESIS, Issue 13 2007
    Adhitasari Suratman
    Abstract Hydrochloric acid was investigated as a rinsing reagent to remove adsorbed proteins from linear polyacrylamide-coated capillaries for electrophoresis. Three model proteins were used, namely cytochrome c as a basic protein, ,-lactoglobulin as an acidic protein, and ,-casein as a more easily denaturing protein. In order to regenerate capillary surfaces, they have been rinsed for 5,min with 2,M hydrochloric acid, 5,min with water, and then 30,min with buffer after every tenth run. It was found important to perform this regeneration procedure on time. The obtained results show good repeatability of the apparent EOF mobility with percentage RSDs below 3% (n,=,60) in various cases. These good results were mainly confirmed in long-term series with more than 200 runs each. Only very high concentrations (175,,M) of ,-lactoglobulin and ,-casein at pH,3.5 gave RSD% values above 5%. For these conditions, the further test of 85% m/m phosphoric acid as rinsing reagent showed a good repeatability of the apparent EOF mobilities as well. [source]

    A microfabricated capillary electrophoresis chip with multiple buried optical fibers and microfocusing lens for multiwavelength detection

    ELECTROPHORESIS, Issue 6 2005
    Suz-Kai Hsiung
    Abstract We present a new microfluidic device utilizing multiwavelength detection for high-throughput capillary electrophoresis (CE). In general, different fluorescent dyes are only excited by light sources with appropriate wavelengths. When excited by an appropriate light source, a fluorescent dye emits specific fluorescence signals of a longer wavelength. This study designs and fabricates plastic micro-CE chips capable of performing multiple-wavelength fluorescence detection by means of multimode optic fiber pairs embedded downstream of the separation channel. For detection purposes, the fluorescence signals are enhanced by positioning microfocusing lens structures at the outlets of the excitation fibers and the inlets of the detection fibers, respectively. The proposed device is capable of detecting multiple samples labeled with different kinds of fluorescent dyes in the same channel in a single run. The experimental results demonstrate that various proteins, including bovine serum albumin and ,-casein, can be successfully injected and detected by coupling two light sources of different wavelengths to the two excitation optic fibers. Furthermore, the proposed device also provides the ability to measure the speed of the samples traveling in the microchannel. The developed multiwavelength micro-CE chip could have significant potential for the analysis of DNA and protein samples. [source]

    Poly(dimethylsiloxane)-based microfluidic device with electrospray ionization-mass spectrometry interface for protein identification

    ELECTROPHORESIS, Issue 21 2003
    Wang-Chou Sung
    Abstract An easy method to fabricate poly(dimethylsiloxane) (PDMS)-based microfluidic chips for protein identification by tandem mass spectrometry is presented. This microchip has typical electrophoretic microchannels, a flow-through sampling inlet, and a sheathless nanoelectrospray ionization (ESI) interface. The surface of the microchannel was modified with 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) and the generated electroosmotic flow under acidic buffer condition used for the separation was found to be more stable compared to that generated by the microchannel without modification. The feasibility of the device for flow-through sampling, separation, and ESI-MS/MS analysis was demonstrated by the analysis of a standard mixture composed of three tryptic peptides. Results show that four peaks corresponding to three peptide standards and acetylated products of the standard peptide were well resolved and the deduced sequences were consistent with those expected. Furthermore, the compatibility of this device with other miniaturized devices to integrate the whole process was also explored by connecting a miniaturized enzymatic digestion cartridge and a desalting cartridge in series to the sampling inlet of the microchip for the identification of a model protein, ,-casein. [source]

    Casein phosphoproteome: Identification of phosphoproteins by combined mass spectrometry and two-dimensional gel electrophoresis

    ELECTROPHORESIS, Issue 16 2003
    Gianfranco Mamone
    Abstract We report a fast and easy-to-use procedure that combines polyacrylamide gel electrophoresis with matrix assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF) and nanoelectrospray-tandem mass spectrometry (nES-MS/MS) analysis for the identification of casein components and defined phosphorylated sites. This methodology ensured identification of more than 30 phosphorylated proteins, five ,-, fifteen ,s1 -, ten ,s2 -, and four ,-casein (CN) components, including nonallelic, differently phosphorylated, and glycosylated forms. The sugar motif covalently bound to ,-CN was identified as chains, trisaccharide GalNAc, Gal, NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc. Also identified was a biantennary chain made up of both chains of trisaccharide 1GalNAc, 1Gal, 1NeuGc, and tetrasaccharide 1GalNAc, 1Gal, 2NeuGc moiety on a single ,-CN component. The phosphate group on site Ser12 of tryptic peptide 8,22 of most phosphorylated ,s1 -CN (11 phosphate groups) was localized and the oligosaccharide sequence of the main tryptic glycopeptides of two ,-CN components was determined by means of MS/MS analysis. [source]

    The feeding behavior of Trichogramma brassicae: new evidence for selective ingestion of solid food

    Z.X. Wu
    Abstract A descriptive study of the feeding behavior and structures of Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) was conducted. Based on direct observational and biochemical evidence, larvae feed predominantly on particulate materials, starting ca. 25 h post-oviposition. Feeding lasted for ca. 9 h, at 251 C. During this feeding period the shape of the larvae changed from vermiform to pyriform and then to sacciform, resulting in a ca. 40-fold increase in body size. Larvae used elaborate feeding behaviors as they pulled solid food particles to their oral opening, broke small particles from larger ones, and took the particles into the stomodaeum, which is a powerful pump. In the stomodaeum, peristaltic movement further macerated the particles, which eventually passed through the cardiac valve into the midgut. As indicated by changes in fluorescently labeled casein, digestive enzymes aid in the extra-oral chemical digestion of food. The contents of the gut, during and shortly after feeding, were almost entirely closely packed solid particles. The behavioral activity of feeding larvae centered almost exclusively on processing and ingesting solid food particles. The rapid larval growth is much more plausibly explained by their feeding on the highly concentrated nutrients found in solid foods, rather than the extensive concentration required if dilute liquids were the principal source of nutrients. The implications of these findings for the development of practical artificial diets are discussed. [source]

    Enterococcus faecalis with the gelatinase phenotype regulated by the fsr operon and with biofilm-forming capacity are common in the agricultural environment

    Lilia Macovei
    Summary The prevalence of gelatinase activity and biofilm formation among environmental enterococci was assessed. In total, 396 enterococcal isolates from swine and cattle faeces and house flies from a cattle farm were screened for gelatinase activity. The most prevalent phenotype on Todd,Hewitt agar with 1.5% skim milk was the weak protease (WP) (72.2% of isolates), followed by the strong protease (SP) 18.7%, and no protease (NP) (9.1%). The majority of WP isolates was represented by Enterococcus hirae (56.9%), followed by Enterococcus faecium (25.9%), Enterococcus casseliflavus (10.4%), Enterococcus gallinarum (5.2%) and Enterococcus saccharolyticus (1.7%). All WP isolates were negative for gelE (gelatinase) and sprE (serine protease) as well as the fsrABDC operon that regulates the two proteases, and only four isolates (7.0%) formed biofilms in vitro. All SP isolates were Enterococcus faecalis positive for the fsrABDC, gelE, sprE genes and the majority (91.2%) formed a biofilm. Diversity of NP isolates was relatively evenly distributed among E. hirae, E. faecium, E. casseliflavus, E. gallinarum, Enterococcus durans, E. saccharolyticus and Enterococcus mundtii. All NP isolates were negative for the fsr operon and only four E. hirae (11.1%) formed a biofilm. Of further interest was the loss of the gelatinase phenotype (18.9% of isolates) from SP isolates after 4 month storage at 4,8C and several passages of subculture. Results of reverse transcription PCR analysis indicated that mRNA was produced for all the genes in the frs operon and sequencing of the gelE gene did not reveal any significant mutations. However, gelatinase was not detectable by Western blot analysis. Our study shows that E. faecalis with the complete fsr operon and the potential to form a biofilm are relatively common in the agricultural environment and may represent a source/reservoir of clinically relevant strains. In addition, many environmental enterococci, especially E. hirae, produce an unknown WP that can hydrolyse casein but does not contribute to biofilm formation. The stability of the gelatinase phenotype in E. faecalis and its regulation will require additional studies. [source]

    Inhibition of hydroxyapatite dissolution by whole casein: the effects of pH, protein concentration, calcium, and ionic strength

    Michele E. Barbour
    Formulating drinks with reduced erosive potential is one approach for reducing dental erosion. In this study, whole casein was added to citric acid solutions representative of soft drinks, and the hydroxyapatite dissolution rate was assessed. Adding 0.02% (w/v) casein to acid solutions significantly reduced the hydroxyapatite dissolution rate by 51 4% at pH values of 2.80, 3.00, 3.20, 3.40, and 3.60, although the baseline dissolution rates of course varied as a function of pH. The protein concentration [0.002, 0.02, and 0.2% (w/v) casein] had no significant effect on dissolution inhibition. Adding both casein and calcium to citric acid resulted in a further reduction in the dissolution rate at low and intermediate calcium concentrations (5 and 10 mM) but not at higher calcium concentrations (20 and 50 mM). Ionic strength had no significant impact on the efficacy of casein. Casein also significantly reduced the hydroxyapatite dissolution rate when the hydroxyapatite was coated with a salivary pellicle. The reduction in dissolution rate is ascribed to firmly adsorbed casein on the hydroxyapatite surface, which stabilizes the crystal surface and inhibits ion detachment. [source]

    Kinetic and crystallographic analysis of complexes formed between elastase and peptides from ,-casein

    FEBS JOURNAL, Issue 10 2001
    Penny A. Wright
    Human ,-casomorphin-7 (NH2 -Tyr-Pro-Phe-Val-Glu-Pro-Ile-CO2H) is a naturally occurring peptide inhibitor of elastase that has been shown to form an acyl-enzyme complex stable enough for X-ray crystallographic analysis at pH 5. To investigate the importance of the N-terminal residues of the ,-casomorphin-7 peptide for the inhibition of elastase, kinetic and crystallographic analyses were undertaken to identify the minimum number of residues required for effective formation of a stable complex between truncated ,-casomorphin-7 peptides and porcine pancreatic elastase (PPE). The results clearly demonstrate that significant inhibition of PPE can be effected by simple tri-, tetra-and pentapeptides terminating in a carboxylic acid. These results also suggest that in vivo regulation of protease activity could be mediated via short peptides as well as by proteins. Crystallographic analysis of the complex formed between N -acetyl-Val-Glu-Pro-Ile-CO2H and PPE at pH 5 (to 1.67 resolution) revealed an active site water molecule in an analogous position to that observed in the PPE/,-casomorphin-7 structure supportive of its assignment as the ,hydrolytic water' in the deacylation step of serine protease catalysis. [source]

    Development and characterization of an animal model of carnitine deficiency

    FEBS JOURNAL, Issue 6 2001
    Markus Spaniol
    Mammals cover their carnitine needs by diet and biosynthesis. The last step of carnitine biosynthesis is the conversion of butyrobetaine to carnitine by butyrobetaine hydroxylase. We investigated the effect of N -trimethyl-hydrazine-3-propionate (THP), a butyrobetaine analogue, on butyrobetaine hydroxylase kinetics, and carnitine biosynthesis and body homeostasis in rats fed a casein-based or a vegetarian diet. The Km of butyrobetaine hydroxylase purified from rat liver was 41 9 molL,1 for butyrobetaine and 37 5 molL,1 for THP, and THP was a competitive inhibitor of butyrobetaine hydroxylase (Ki 16 2 molL,1). In rats fed a vegetarian diet, renal excretion of total carnitine was increased by THP (20 mg100 g,1day,1 for three weeks), averaging 96 36 and 5.3 1.2 molday,1 in THP-treated and control rats, respectively. After three weeks of treatment, the total carnitine plasma concentration (8.8 2.1 versus 52.8 11.4 molL,1) and tissue levels were decreased in THP-treated rats (liver 0.19 0.03 versus 0.59 0.08 and muscle 0.24 0.04 versus 1.07 0.13 molg,1). Carnitine biosynthesis was blocked in THP-treated rats (,0.22 0.13 versus 0.57 0.21 mol100 g,1day,1). Similar results were obtained in rats treated with the casein-based diet. THP inhibited carnitine transport by rat renal brush-border membrane vesicles competitively (Ki 41 3 molL,1). Palmitate metabolism in vivo was impaired in THP-treated rats and the livers showed mixed steatosis. Steady-state mRNA levels of the carnitine transporter rat OCTN2 were increased in THP-treated rats in skeletal muscle and small intestine. In conclusion, THP inhibits butyrobetaine hydroxylase competitively, blocks carnitine biosynthesis in vivo and interacts competitively with renal carnitine reabsorption. THP-treated rats develop systemic carnitine deficiency over three weeks and can therefore serve as an animal model for human carnitine deficiency. [source]

    Cloning of MMP-26

    FEBS JOURNAL, Issue 11 2000
    A novel matrilysin-like proteinase
    A cDNA encoding a novel human matrix metalloproteinase (MMP), named MMP-26, was cloned from fetal cDNA. The deduced 261-amino-acid sequence is homologous to macrophage metalloelastase (51.8% identity). It includes only the minimal characteristic features of the MMP family: a signal peptide, a prodomain and a catalytic domain. As with MMP-7, this new MMP does not comprise the hemopexin domain, which is believed to be involved in substrate recognition. A study of MMP-26 mRNA steady states levels reveals, among the tissue examined, a specific expression in placenta. MMP-26 mRNA could also be detected in several human cell lines such as HEK 293 kidney cells and HFB1 lymphoma cells. Recombinant MMP-26 was produced in mammalian cells and used to demonstrate a proteolytic activity of the enzyme on gelatin and ,-casein. [source]

    Characterization of the PCR inhibitory effect of bile to optimize real-time PCR detection of Helicobacter species

    Waleed Abu Al-Soud
    Abstract The inhibitory effect of human and porcine bile samples to detect Helicobacter DNA was studied by adding different concentrations of bile samples to PCR mixtures of six thermostable DNA polymerases containing cagA specific primers and Helicobacter pylori DNA. PCR products were amplified by using the Rotorgene system and SYBR Green I. Among the six DNA polymerases tested, rTth had the lowest sensitivity to bile inhibitors, whereas Taq and Tfl had the highest sensitivity. Bile proteins did not inhibit AmpliTaq DNA polymerase, whereas the fraction containing mainly bile acids and their salts inhibited the amplification capacity of AmpliTaq. Heating human bile at 98 C and adding casein and formamide to the reaction mixture reduced the PCR inhibitory effect of bile. Therefore, a pre-PCR treatment based on dilution and heating of bile, adding casein and formamide to the reaction mixture of rTth DNA polymerase was found efficient to amplify DNA directly in bile. [source]

    Mucilaginibacter dorajii sp. nov., isolated from the rhizosphere of Platycodon grandiflorum

    Byung-Chun Kim
    Abstract A Gram-negative, nonmotile and rod-shaped bacterial strain was isolated from the rhizosphere of Platycodon grandiflorum in a study of bacterial diversity, and its taxonomic position was investigated by a genotypic and phenotypic analysis. This isolate, designated as DR-f4, grew at 4,30 C (optimally at 20,25 C) and in the presence of 0,1% (w/v) NaCl. It contained MK-7 as the predominant menaquinone. The isolate had activities of catalase, oxidase and ,-galactosidase and hydrolyzed aesculin, casein, carboxymethyl-cellulose, starch and l -tyrosine. The major cellular fatty acids were summed feature 3 (C16:1,7c and/or iso-C15:0 2OH) and iso-C15:0. The DNA G+C content was 42.6 mol%. This isolate belonged to the genus Mucilaginibacter based on phylogenetic analysis using 16S rRNA gene sequences. The nearest phylogenetic neighbors of strain DR-f4T were Mucilaginibacter lappiensis ANJL12T and Mucilaginibacter rigui WPCB133T, with 16S rRNA gene sequence similarity levels of 96.9% and 96.4%, respectively. The genotypic and phenotypic evidence suggests that strain DR-f4T should be classified as a novel species, for which the name Mucilaginibacter dorajii sp. nov. is proposed. The type strain for the novel species is DR-f4T (=KACC 14556T=JCM 16601T). [source]

    The acute-phase response impairs host defence against Enterococcus faecium peritonitis

    IMMUNOLOGY, Issue 1pt2 2009
    Masja Leendertse
    Summary Enterococcus faecium is an emerging pathogen that causes infections in hospitalized patients with various co-morbid diseases. These underlying diseases are often associated with an acute-phase response that renders patients vulnerable to nosocomial infections. To study the influence of the acute-phase response induced by sterile tissue injury on host defence against E. faecium, mice were injected subcutaneously with either turpentine or casein 1 day before intraperitoneal infection with E. faecium. Control mice were subcutaneously injected with saline or sodium bicarbonate, respectively. Turpentine and casein induced an acute-phase response as reflected by increases in the plasma concentrations of interleukin-6, serum amyloid P and C3. A pre-existent acute-phase response in mice was associated with a strongly reduced capacity to clear E. faecium, resulting in prolonged bacteraemia for several days. The inflammatory response to E. faecium was impaired in mice with an acute-phase response, as shown by reduced capacity to mount a neutrophilic leucocytosis in peripheral blood and by decreased local cytokine concentrations. These data indicate that the acute-phase response impairs host defence against E. faecium, suggesting that this condition may contribute to the increased vulnerability of critically ill patients to enterococcal infections. [source]

    Influence of whey peptides on the surface activity of ,-casein and ,-lactoglobulin A

    Whey protein hydrolysate (WPH) was fractionated by reverse-phase chromatography to obtain fractions of varying surface-hydrophobicities. A model oil,water interface (MI) was pre-coated with the WPH or fractions thereof. Contact angle (,) of sessile drops of ,-casein (,-CN) or ,-lactoglobulin A (,-LGA) were measured on the MI. Pre-coating of MI with un-fractionated WPH decreased ,, that is, increased surface activity, of both ,-CN (35,8.3) and ,-LGA (38,21.3). Conversely, pre-coating of MI with the fractions significantly increased , of both proteins as a function of hydrophobicity. Data provide insight into variability of whey protein functionality in food applications. [source]

    Effect of somatic cell counts on lipolysis, proteolysis and apparent viscosity of UHT milk during storage

    In this work, lipolysis, proteolysis and viscosity of ultra-high temperature (UHT) milk containing different somatic cell counts (SCC) were investigated. UHT milks were analysed on days 8, 30, 60, 90 and 120 of storage. Lipolysis as measured by free fatty acids increase, casein degradation and viscosity of UHT milk were not affected by SCC but increased during storage. A negative relationship was observed between SCC and casein as a percentage of true protein on the 120th day of storage, hence indicating that high SCC increases the proteolysis of UHT milk by the end of its shelf life. [source]

    Characteristics of traditional Croatian ewe's cheese from the island of Krk

    Krk cheese is a hard, full-fat cheese made from raw sheep's milk, characterized by a delicate, full and strong flavour. The aim of this study was to determine farm influence on the chemical composition of sheep's milk for Krk cheese production, and the chemical characteristics of Krk cheese during ripening. Gross composition of the milk used complies with the average sheep's milk composition from the Croatian Adriatic region. During ripening, fat, protein, salt content and lactic acid concentration increased (P < 0.01), as well as the water-soluble nitrogen fraction and the 12%-trichloroacetic-acid-soluble nitrogen fraction (P < 0.05). Degradation of ,-casein could be an indicator of the ripening quality of Krk cheese. [source]

    Ripening of Camembert-type cheese made from caprine milk using calf rennet or kid rennet as coagulant

    Camembert-type cheese was made from caprine milk using either calf rennet or kid ,Grandine' rennet as coagulant. The pH of all cheeses increased throughout ripening and levels of pH 4.6-soluble nitrogen increased from 8.1 to 18.2% of total nitrogen (TN) and from 6.9 to 20% TN for the cheeses made using calf rennet and kid rennet, respectively. Degradation of ,-casein, measured by urea,polyacrylamide gel electrophoresis, and total and free amino acids were greater in the cheese made using kid rennet. Production of peptides, analysed by high performance liquid chromatography (HPLC), was slightly more extensive in the Camembert-type cheese made using calf rennet as coagulant. In general, a higher degree of proteolysis was found in Camembert-type cheese made from caprine milk using kid rennet than in cheese made using calf rennet as coagulant. [source]

    Maribo cheese manufactured with concentrated milk: characteristics, maturation and yield

    Research was carried out to study the feasibility of making maribo cheese using milk fortified by the addition of skim milk powder. A control (T-C) with 82 g l -1 solids-non-fat (SNF) and 32 g l -1 milk fat was included, along with three treatments with 11.7 (T-1), 14.6 (T-2) and 16.6 g l -1 SNF (T-3) and standardization of the milk fat. Some chemical characteristics of the cheese milks and of the endproducts were studied and, in addition, cheese yield and the progress of maturation were monitored. It was observed that, as maturation proceeded in all treatments, there was a steady increase in the ripening index (soluble nitrogen/total nitrogen %), which indicates a progressive advance of proteolysis. Nevertheless, there were significant differences (p <.05) between the ripening indices of the control and the rest of the treatments. Furthermore, as the extent of maturation increased, ,sl -casein was degraded more than ,-casein. The yield of cheese increased proportionally as the concentration of non-fat-solids in the milk increased. [source]

    Proteolysis and texture changes of a Spanish soft cheese (,Torta del Casar') manufactured with raw ewe milk and vegetable rennet during ripening

    Delgado Francisco-Jos
    Summary Proteolysis and textural changes of the Spanish ewe raw milk soft cheese of the Protected Designation of Origin Torta del Casar were studied in four different stages of ripening, with 1, 30, 60 and 90 days. In general, proteolysis in Torta del Casar cheese was weak at 1 and 30 days and it was more intense between the 30,60 days of ripening. Soluble nitrogen non-protein nitrogen, polypeptide N and free amino acids values significantly increased during cheese ripening. Protein and casein nitrogen decreased significantly after 60 days of ripening resulting in the increase of the other nitrogen fractions measured. Caseins changes determined by capillary zone electrophoresis showed that proteolysis of ,-casein occurred faster than ,s1-casein but the latter suffered higher proteolytic degradation at the end of ripening (day 90). This pattern of degradation of caseins is reversed in other cheeses made with animal rennet. Texture analysis showed that firmness and consistency decreased along ripening while adhesiveness increased. Highly significant correlations were found between textural parameters, residual caseins levels and nitrogen fractions during maturation, which shows the importance of proteolytic changes for an optimal texture formation. [source]

    The hydrophilic, foaming and emulsifying properties of casein concentrates produced by various methods

    Janesca A. Roman
    Summary The hydrophilic and surfactant properties of casein concentrates made by different processes such as isoelectric precipitation and neutralization (commercial casein, CC) coagulation by rennet (casein clots, COC) and microfiltration/diafiltration (casein micelles, CM) were studied. Water absorption capacity (WAC), water solubility (WS) and water-holding capacity (WHC) were highest for CM and lowest for COC. Solubility was higher in water and in pH 5.5, 0.10 m NaCl solution for both CM and COC. Foaming capacity was better for CM than for CC at pH 4.0 and for CC at pH 6.0 and 8.0. Foam stability was low for both CM and CC at pH 4.0 but it was high for CM at pH 6.0 and 8.0 and for CC in the absence of salt. Emulsifying capacity was higher for CC at pH 4.0 and 7.0. Stability of emulsion was high for CC at pH 4.0 and for CM at pH 7.0. [source]