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Search Results: 1 - 10 of 108 matches for " proteolysis "
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The effect of milling on proteins in model Queso Fresco cheeses  [PDF]
Moushumi Paul, Alberto Nu?ez, Diane Van Hekken
Advances in Bioscience and Biotechnology (ABB) , 2012, DOI: 10.4236/abb.2012.31001
Abstract: Raw milk Queso Fresco (QF) made in Mexico contains contaminating bacterial strains that are not permitted in US foods. There is interest in developing a pasteurized milk version of Mexican Queso Fresco to be sold in the US. Milling is one of many manufacturing factors that may influence protein integrity. The aim of this study is to assess the effect of milling procedures on protein composition and cheese functional properties in a model QF, made without starter cultures. Mass spectrometric and gel electrophoretic analyses of aged milled cheeses show minimal changes in protein content without differences among the milling techniques. In these novel QF-like cheeses, eight weeks of aging, regardless of milling type, results in cheeses that is very similar to the non-aged samples. Aged cheeses with minimal proteolysis imply an extended shelf life and therefore, model cheeses from this study, relative to Mexican raw milk cheeses, would stay fresher in American households and supermarkets longer.
Keratinolytic bacteria isolated from feather waste
Riffel, Alessandro;Brandelli, Adriano;
Brazilian Journal of Microbiology , 2006, DOI: 10.1590/S1517-83822006000300036
Abstract: the aim of this study was to characterize keratinolytic bacteria isolated from feather waste. four isolates were selected after growth on solid medium with feather meal as sole carbon and nitrogen source and screened for proteolytic activity on milk agar plates. three isolates were gram-negative (belonged to the genera burkholderia, chryseobacterium and pseudomonas) and one was gram-positive (microbacterium sp.). these bacteria grew on diverse keratin wastes such as feather meal, raw feathers, chicken nails, hair and wool. keratinase activity was detected during growth, but the complete degradation of these substrates was not always achieved. the proteolytic character of crude enzymes was assessed using azokeratin and azocasein as substrates. the keratinases were active on both substrates and were similar in keratin hydrolysis when compared with commercially available microbial peptidases. these novel keratinolytic isolates have potential biotechnological use in processes involving keratin hydrolysis.
CHANGES ON PHYSICOCHEMICAL, LIPOLYSIS AND PROTEOLYSIS OF VACUUMPACKED TURKISH KASHAR CHEESE DURING RIPENING
Zekai Tarakci,Erdogan Kucukoner
Journal of Central European Agriculture , 2007,
Abstract: The vacuum-packed Turkish Kashar cheese ripening was evaluated in the medium and internal zones of cheese throughout a 90 day storage period. The parameters analyzed were; lipolysis level, water soluble nitrogen (WSN), total nitrogen, ripening index (RI), trichloroacetic acid-soluble nitrogen (TCA-SN), moisture, salt and salt in moisture, fat values and sensorial properties. The moisture values, acidity, salt and salt in moisture was less internal section. The lipolysis level, RI, TCA-SN ratios of internal section of cheese was less than medium section. Lipolysis level, RI, TCA-SN values, salt content and salt in moisture of the cheese samples increased continuously until end of the ripening but total nitrogen and fat content shown no signifi cant changes with ripening, as moisture values decreased slightly. The ripening period was the main factor affecting sensory properties of cheese in medium and internal zones.
Different behavior of protein B23/nucleophosmin and UBF in HeLa cells during apoptosis  [PDF]
Natalia M. Vladimirova, Natalia A. Potapenko
Journal of Biophysical Chemistry (JBPC) , 2011, DOI: 10.4236/jbpc.2011.24049
Abstract: The behavior of UBF (upstream binding factor) and nucleophosmin in HeLa and HeLa-Bcl-2 cells during apoptosis induced by TNF-α, emetine, and their mixture was investigated. A pronounced apoptosis was achieved only in HeLa cells treated with a mixture of the inducers. Immunoblotting analysis of UBF and nucleophosmin in samples containing different portions of cells with apoptotic nuclei was carried out. It showed that UBF was proteolytically cleaved giving a stable 76-kDa fragment. Increasing content of the fragment during apoptosis correlated with the level of cells containing apoptotic nuclei and with a decrease in the content of full-sized UBF. Determination of N- and C-terminal sequences of UBF and 76-kDa fragment allowed us not only to characterize UBF at the protein level, but also to describe the site of the apoptosis-specific proteolysis. Nucleophosmin did not undergo proteolytic cleavage during apoptosis and its content was unchanged even in a sample containing 100% of cells with apoptotic nuclei. However in cells reached terminal stages of apoptosis, the balance between mono- and oligomeric forms of nucleophosmin changed due to depletion of monomeric forms and appearance of two additional oligomeric forms with lower molecular weight.
Inhibitors of protein kinases affecting cAMP-dependent proteolysis of GATA-6  [PDF]
Hironori Ushijima, Masatomo Maeda
Advances in Biological Chemistry (ABC) , 2012, DOI: 10.4236/abc.2012.24051
Abstract: We screened 95 kinase inhibitors whether they affect cAMP-dependent proteolysis of GATA-6 or not. Among them 7 inhibitors inhibited the proteolysis at the concentration range of μM around their IC50. They are inhibitors for protein kinase A (H-89 and 4- cyano-3-methylisoquinoline), c-Jun N-terminal kinase (SP600125), phosphatidylinositol 3-kinase (Wort- mannin and LY-294002), casein kinase II (TBB) and cyclin dependent kinase (Cdk1/2 inhibitor III). It is of interest how these kinases play roles in the degradation process of GATA-6 since this transcription factor is essential for development and tissue-specific gene expression of mammals. Inhibitors identified in this study would be helpful to study molecular mechanisms of phenomena in which GATA-6 participates.
Bioactive Low Molecular Weight Compounds in Two Traditional Spanish Products  [PDF]
María Luisa Timón, Emilio José Galea, Ana Isabel Andrés, María Jesús Petrón
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.49A2003
Abstract:

The aim of this work focuses on the study of low molecular weight (LMW) compounds with antioxidant and antihy-pertensive effect in Iberian ham and La Serena cheese, two traditional products in Spain, in comparison to cured ham and matured Ewe’s milk cheese. Proteolysis parameters were studied, LMW compounds were isolated and their antioxidant and antihypertensive activity was analyzed. Results showed that a more intense proteolysis, expressed as peptidic nitrogen (PN), in Iberian ham (p < 0.001), can cause higher antioxidant activity in this product for both DPPH radical scavenging (p < 0.001) and metal chelating effect (p < 0.001). However, a more intense proteolysis in La Serena cheese, expressed as non protein nitrogen (NPN) (p < 0.001) and PN (p < 0.001), did not promote higher antioxidant activity in this cheese. On the other hand, no differences were found for antihypertensive activity, expressed as angiotensin I-converting enzyme (ACE) inhibitory activity, in both type of hams or cheese.

Viability and Proteolytic Capacity of Lactobacillus bulgaricus 2772 and Lactobacillus rhamnosus GG during Cheese Ripening  [PDF]
G. M. Rodriguez-Serrano, L. G. González-Olivares, Z. L. López-Cuellar, J. A?orve-Morga, M. J. Franco-Fernández, A. Casta?eda-Ovando, E. Contreras López, J. Jaimez Ordaz
Journal of Biosciences and Medicines (JBM) , 2014, DOI: 10.4236/jbm.2014.23002
Abstract: Nowadays, probiotics have been utilized as starter cultures in the elaboration of fermented dairy products such as cheese. The survival of probiotic microorganisms in this type of products is very important in order to have a beneficial effect after their consumption. In addition to this, milk proteins are considered an important source of bioactive peptides. These peptides have been identified in hydrolyzed products of milk proteins and dairy products such as cheese. In this study, the protective effect on the survival of Lactobacillus rhamnosus GG was determined in a cheese which was inoculated only with this probiotic microorganism, and in another cheese additionally inoculated with Lactobacillus bulgaricus 2772 (exopolysaccharide producer bacteria). The ripening of these cheeses took place for 28 days at two different temperatures (4°C and 14°C). The proteolytic?capacity was analyzed by measuring the concentration of free amino groups, through the trinitrobenzenesulfonic acid method (TNBS). The separation of peptides was carried out by polyacrylamide gel electrophoresis (SDS-PAGE) with 15% T. At the end of the study it was found that the population density was higher in the cheeses ripened at 14°C while at 4°C, it decreased. A?higher proteolytic activity at 14°C was also observed and it was determined by a higher concentration of free amino groups. Likewise, during the analysis of electrophoresis gels, a higher concentration of peptides smaller than 10 kDa was found in the samples of cheeses ripened at 14°C. These results increase the expectations to find peptides with a biological function.
Dexamethasone protected human glioblastoma U87MG cells from temozolomide induced apoptosis by maintaining Bax:Bcl-2 ratio and preventing proteolytic activities
Arabinda Das, Naren L Banik, Sunil J Patel, Swapan K Ray
Molecular Cancer , 2004, DOI: 10.1186/1476-4598-3-36
Abstract: Freshly grown cells were treated with different doses of DXM or TMZ for 6 h followed by incubation in a drug-free medium for 48 h. Wright staining and ApopTag assay showed no apoptosis in cells treated with 40 μM DXM but considerable amounts of apoptosis in cells treated with 100 μM TMZ. Apoptosis in TMZ treated cells was associated with an increase in intracellular free [Ca2+], as determined by fura-2 assay. Western blot analyses showed alternations in the levels of Bax (pro-apoptotic) and Bcl-2 (anti-apoptotic) proteins resulting in increased Bax:Bcl-2 ratio in TMZ treated cells. Western blot analyses also detected overexpression of calpain and caspase-3, which cleaved 270 kD α-spectrin at specific sites for generation of 145 and 120 kD spectrin break down products (SBDPs), respectively. However, 1-h pretreatment of cells with 40 μM DXM dramatically decreased TMZ induced apoptosis, decreasing Bax:Bcl-2 ratio and SBDPs.Our results revealed an antagonistic effect of DXM on TMZ induced apoptosis in human glioblastoma U87MG cells, implying that treatment of glioblastoma patients with DXM prior to chemotherapy with TMZ might result in an undesirable clinical outcome.Glioblastoma patients usually receive steroids for alleviation of vasogenic edema and pain prior to treatment with chemotherapeutic drugs. Steroids, however, may modulate the sensitivity of tumor cells to chemotherapeutic drugs. Dexamethasone (DXM), a synthetic glucocorticoid, is commonly used to reduce inflammation and pain associated with glioblastoma [1]. However, DXM has been reported to make human glioblastoma cells resistant to ionizing radiation and chemotherapeutic agents that otherwise cause DNA damage [2-5]. Execution of cells by apoptosis usually requires the activation of cysteine proteases such as calpains and caspases [6]. Diverse stimuli may cause an increase in intracellular free [Ca2+], which is absolutely required for activation of calpain [7]. Activation of caspases may occur via differen
Péptidos bioactivos derivados de las proteínas de la leche
Torres-Llanez,María de Jesús; Vallejo-Cordoba,Belinda; González-Córdova,Aarón Fernando;
Archivos Latinoamericanos de Nutrición , 2005,
Abstract: milk proteins are known for having a wide range of nutritional, functional and biological properties that make them important ingredients in functional or health promoting foods. these properties are partly attributed to bioactive peptides coded in the different milk proteins. bioactive peptides are inactive within the protein sequence but may be released by the action of native proteolitic enzymes from milk, enzymes from lactic acid bacteria or from exogenous sources or may be produced during gastrointestinal digestion or processing of foods. peptides derived from caseins and whey proteins were shown to present several bioactive properties such as opioid, antihypertensive, antimicrobial, immunodulatory, mineral carrier and antithrombotic. this overview presents a perspective of the importance of dairy proteins in the production of bioactive peptides and their biological activities, as well as the main analytical tecniques that have been used for the isolation and identification of these peptides.
Elimination of turbidity interference in serum iron colorimetric assay by enzymatic proteolysis
Cardoso, Leonardo M.;Andrade, Milton H. G. de;Chianca Junior, Deoclécio A.;Silva, Marcelo Eustáquio;Pedrosa, Maria Lúcia;
Brazilian Archives of Biology and Technology , 2003, DOI: 10.1590/S1516-89132003000300019
Abstract: we describe a modification in the commercial colorimetric method for the determination of serum iron by using ferrozine? . the modification was proposed because during the conventional procedure, turbidity observed when the serum of animals submitted to surgery was used interfered with the assay. we added to the original method, a previous treatment of the serum with proteolytic enzymes. this modification was also tested using plasma samples, although this was not recommended when the original method was used. the results demonstrated that: a) the treatment with a mixture of trypsin and chymotrypsin was effective in order to eliminate turbidity; b) there was no difference between the standard curves obtained by the conventional and the modified method for control assays; c) the absorbencies of the samples of serum and plasma submitted to proteolysis, estimated by the addition of different concentrations of iron, were directly proportional to iron concentrations; d) the pre-treatment with enzymes allowed the utilization of plasma; e) the pre-treatment with guanidine. hcl was not effective.
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