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Various Proteins (various + protein)
Selected AbstractsMicropipette manipulation: A technique to evaluate the stability of water-in-oil emulsions containing proteinsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2004Lene Jorgensen Abstract The interfacial properties and stability of water-in-oil emulsions containing protein were studied using micromanipulation. Micropipettes were used to produce individual water droplets in oil in a controlled manner on the micron scale. The pipettes were then used to bring two droplets into contact in order to observe fusion. The occurrence of fusion was investigated as a function of the compositions of both the continuous (oil) and dispersed (aqueous) phases. Various proteins, i.e., insulin, growth hormone, or serum albumin, were dissolved in the dispersed phase. When low concentrations of surfactants or no surfactant were present in the oil phase, a condensed protein film was formed at the surface of the droplets, which was revealed by the irregular topology of the droplet surface viewed with contrast microscopy. At higher surfactant concentrations, this topology was not observed nor was the stability apparently affected; emulsion droplets coalesce immediately upon contact with each other. There seems to be a limiting surfactant concentration, which stabilizes the droplets toward fusion and prevents formation of a condensed surface film, when the droplets contain protein. The technique exhibits potential for examination of the effects of various excipients on the coalescence stability of emulsion droplets. © 2004 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 93:2994,3003, 2004 [source] Effects of dietary starches and the protein to energy ratio on growth and feed efficiency of juvenile cobia, Rachycentron canadumAQUACULTURE NUTRITION, Issue 5 2010K.A. JR WEBB Abstract Optimization of the protein to energy ratio in juvenile cobia (Rachycentron canadum) would allow the production of diets that maximize growth without the addition of excess energy that may increase costs or even be detrimental to the health of the fish. During a 6-week growth trial, juvenile cobia (5.6 ± 0.5 g fish,1 initial weight) were fed five isonitrogenous and isolipidic diets containing various protein to energy ratios using starch as the energy source. At the end of the trial, some fish were analysed for body composition characteristics while the rest were used to examine the excretion of dietary starch in the feces. Survival and growth were not significantly affected, but feed efficiency (ranging from 0.64 to 0.94) and daily consumption (ranging from 45.3 to 64.1 g kg,1 of body weight d,1) were affected. No reduction in consumption due to excess energy was noted. Analysis of the fecal carbohydrate data showed a linear relationship between dietary inclusion and excretion of carbohydrates with no sign of reaching saturation. Results of this study suggest that cobia can utilize dietary carbohydrates up to at least 340 g kg,1 of dry diet with an optimal protein to energy ratio of approximately 34 mg protein kJ,1metabolizable energy. [source] Growth, feed utilization and body composition of African bonytongue, Heterotis niloticus, fingerlings fed diets containing various protein and lipid levelsAQUACULTURE RESEARCH, Issue 10 2010Serge-Eric Monentcham Abstract In order to evaluate the effects of dietary protein and lipid levels on the growth, feed utilization and body composition of Heterotis niloticus fingerlings, a factorial experiment with three replicates was conducted. Six experimental diets containing three crude protein levels (28%, 32% and 36%) and two crude lipid levels (6% and 13%) were tested. Heterotis niloticus (2.34 g) were fed with the diets to apparent satiation, twice a day. For 56 days, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein retention (PR) were significantly affected by dietary protein and dietary lipid levels respectively (P<0.01). The highest WG, SGR and FE were observed for fingerlings fed the diet containing 36% protein and 6% lipid, but no significance difference was found between groups fed with the following diets: P28L13 (28% protein and 13% lipid), P32L6, P32L13 and P36L13. A significant interaction between dietary protein and lipid was observed for WG, SGR, FE and PR. The whole-body protein, lipid, moisture and ash content were not significantly affected by dietary lipid levels, but body protein and lipid content were significantly affected by dietary protein. The dietary protein-sparing effect was clearly demonstrated when the dietary energy of lipid increased from 17 to 19.6 kJ g,1 at 28% crude protein on H. niloticus. [source] A microfabricated capillary electrophoresis chip with multiple buried optical fibers and microfocusing lens for multiwavelength detectionELECTROPHORESIS, Issue 6 2005Suz-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] Proteomic analysis of cellular responses to low concentration N -methyl- N,-nitro- N -nitrosoguanidine in human amnion FL cellsENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2 2004Jinghua Jin Abstract We have shown previously that exposure to a low concentration of N -methyl- N,-nitro- N -nitrosoguanidine (MNNG) induces comprehensive changes in the protein expression profile of human amnion FL cells, including the induction, suppression, upregulation, and downregulation of various proteins. In addition, by proteomic analysis combining two-dimensional gel electrophoresis (2-DE) and mass spectrometry, some of the induced and suppressed proteins were identified. In this study, we identified an additional 18 proteins among those that were either up- or downregulated by MNNG treatment. The proteins identified were a heterogeneous group that included several zinc finger proteins, proteins involved in signal transduction, cytoskeletal proteins, cell-cycle regulation proteins, and proteins with unknown functions. The involvement of these proteins in the cellular responses to alkylating agents has not been reported before and their physiological relevance is not clear. Therefore, our findings may help better understand the global cellular stress responses to chemical carcinogens, and may lead to new studies on the functions of these MNNG-responsive proteins. Furthermore, some of these proteins may serve as biomarkers for detecting exposure of human populations to environmental carcinogens. Environ. Mol. Mutagen. 43:93,99, 2004. © 2004 Wiley-Liss, Inc. [source] The heat shock protein 70 molecular chaperone network in the pancreatic endoplasmic reticulum , a quantitative approachFEBS JOURNAL, Issue 19 2007Andreas Weitzmann Traditionally, the canine pancreatic endoplasmic reticulum (ER) has been the workhorse for cell-free studies on protein transport into the mammalian ER. These studies have revealed multiple roles for the major ER-luminal heat shock protein (Hsp) 70, IgG heavy chain-binding protein (BiP), at least one of which also involves the second ER-luminal Hsp70, glucose-regulated protein (Grp) 170. In addition, at least one of these BiP activities depends on Hsp40. Up to now, five Hsp40s and two nucleotide exchange factors, Sil1 and Grp170, have been identified in the ER of different mammalian cell types. Here we quantified the various proteins of this chaperone network in canine pancreatic rough microsomes. We also characterized the various purified proteins with respect to their affinities for BiP and their effect on the ATPase activity of BiP. The results identify Grp170 as the major nucleotide exchange factor for BiP, and the resident ER-membrane proteins ER-resident J-domain protein 1 plus ER-resident J-domain protein 2/Sec63 as prime candidates for cochaperones of BiP in protein transport in the pancreatic ER. Thus, these data represent a comprehensive analysis of the BiP chaperone network that was recently linked to two human inherited diseases, polycystic liver disease and Marinesco,Sjögren syndrome. [source] Two major Smad pathways in TGF-, superfamily signallingGENES TO CELLS, Issue 12 2002Keiji Miyazawa Members of the transforming growth factor-, (TGF-,) superfamily bind to two different serine/threonine kinase receptors, i.e. type I and type II receptors. Upon ligand binding, type I receptors specifically activate intracellular Smad proteins. R-Smads are direct substrates of type I receptors; Smads 2 and 3 are specifically activated by activin/nodal and TGF-, type I receptors, whereas Smads 1, 5 and 8 are activated by BMP type I receptors. Nearly 30 proteins have been identified as members of the TGF-, superfamily in mammals, and can be classified based on whether they activate activin/TGF-,-specific R-Smads (AR-Smads) or BMP-specific R-Smads (BR-Smads). R-Smads form complexes with Co-Smads and translocate into the nucleus, where they regulate the transcription of target genes. AR-Smads bind to various proteins, including transcription factors and transcriptional co-activators or co-repressors, whereas BR-Smads interact with other proteins less efficiently than AR-Smads. Id proteins are induced by BR-Smads, and play important roles in exhibiting some biological effects of BMPs. Understanding the mechanisms of TGF-, superfamily signalling is thus important for the development of new ways to treat various clinical diseases in which TGF-, superfamily signalling is involved. [source] Nucleocytoplasmic protein traffic and its significance to cell functionGENES TO CELLS, Issue 10 2000Yoshihiro Yoneda In eukaryotic cells, cell functions are maintained in an orderly manner through the continuous traffic of various proteins between the cell nucleus and the cytoplasm. The nuclear import and export of proteins occurs through nuclear pore complexes and typically requires specific signals: the nuclear localization signal and nuclear export signal, respectively. The transport pathways have been found to be highly divergent, but are known to be largely mediated by importin ,-like transport receptor family molecules. These receptor molecules bind to and carry their cargoes directly or via adapter molecules. A small GTPase Ran ensures the directionality of nuclear transport by regulating the interaction between the receptors and their cargoes through its GTP/GDP cycle. Moreover, it has been recently elucidated how the transport system is involved in various functions of cell physiology, such as cell cycle control. [source] Protein Detecting Arrays Based on Cationic Polythiophene,DNA-Aptamer Complexes,ADVANCED MATERIALS, Issue 20 2006Abérem, M. Béra By combining an appropriate DNA aptamer with a cationic polythiophene optical transducer, human thrombin can be specifically detected on microarrays in the attomole range in less than one hour without any tagging of the target. The system can be modified and utilized as a probe for the detection of various proteins or other biomolecules. This work opens new interesting possibilities for simple and rapid multiparametric analysis in genomics and proteomics. [source] The penetration enhancement and the lipolytic effects of TAT,GKH, both in in vitro, ex vivo, and in vivoINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2004J. Lim It was demonstrated that the trans-activating transcriptional activator (TAT) protein from HIV-1 could enter cells when added to the surrounding media. TAT peptide chemically attached to various proteins was able to deliver these proteins to various cells and even at high levels in heart and spleen tissues in mice. In this study, the tri-peptide GKH (glycine,lysine,histidine) derived from the parathyroid hormone, which is known as a lipolytic peptide, was attached to 9-poly lysine (TAT) to be used as a cosmetic ingredient for eye-bag care product. When glycerol is released, expressed as the extracellular glycerol concentration (the so-called lipolysis index), TAT,GKH at 10,5m induces a maximal lipolytic effect of approximately 41.5% in epididymal adipocytes isolated from rats, compared with basal lipolysis. In a microdialysis study, TAT,GKH was perfused into epididymal adipose tissues of anaesthetized rats in increasing concentrations in a Ringer solution. The glycerol concentration in each dialysate was measured using an ultra-sensitive radiometric method. The perfusion of TAT,GKH induced a lipolytic effect. A penetration study showed that TAT,GKH resulted in a sevenfold higher penetration into excised hairless mice skin than GKH. An in vivo study showed that a TAT,GKH containing emulsion had a better effect upon the relative volume reduction of eye bag after 28 days of application on 22 healthy female volunteers than the placebo. It was therefore concluded that TAT,GKH increased skin penetration, which resulted in enhanced lipolytic effects in in vitro, ex vivo and in volume reduction of eye-bags in in vivo studies. [source] Amino acid ingestion and glucose metabolism,A reviewIUBMB LIFE, Issue 9 2010Mary C. Gannon Abstract Interest in the effect of proteins or amino acids on glucose metabolism dates back at least a century, largely because it was demonstrated that the amino acids from ingested protein could be converted into glucose. Indeed, these observations influenced the dietary information provided to people with diabetes. Subsequently it was shown that ingested protein did not raise the blood glucose concentration. It also was shown that proteins could stimulate a rise in insulin and glucagon but the response to various proteins was different. In addition, it was shown that individual amino acids also could stimulate a rise in insulin and in glucagon concentrations. When individual amino acids are ingested by normal subjects, there is an ordering of the insulin and glucagon responses. However, the order is not the same for insulin and glucagon. In addition, the metabolic response cannot be predicted based on the functional groups of the amino acids. Thus, empirical prediction of the metabolic response to ingested single amino acids is not possible. © 2010 IUBMB IUBMB Life, 62(9): 660,668, 2010 [source] Chaperone-like activity and hydrophobicity of ,-crystallinIUBMB LIFE, Issue 11 2006G. Bhanuprakash Reddy Abstract ,-Crystallin, a prominent member of small heat shock protein (sHsp) family and a major structural protein of the eye lens is a large polydisperse oligomer of two isoforms, ,A- and ,B-crystallins. Numerous studies have demonstrated that ,-crystallin functions like a molecular chaperone in preventing the aggregation of various proteins under a wide range of stress conditions. The molecular chaperone function of ,-crystallin is thus considered to be vital in the maintenance of lens transparency and in cataract prevention. ,-Crystallin selectively interacts with non-native proteins thereby preventing them from aggregation and helps maintain them in a folding competent state. It has been proposed and generally accepted that ,-crystallin suppresses the aggregation of other proteins through the interaction between hydrophobic patches on its surface and exposed hydrophobic sites of partially unfolded substrate protein. However, a quantifiable relationship between hydrophobicity and chaperone-like activity remains a matter to be concerned about. On an attentive review of studies on ,-crystallin chaperone-like activity, particularly the studies that have direct or indirect implications to hydrophobicity and chaperone-like activity, we found several instances wherein the correlation between hydrophobicity and its chaperone-like activity is paradoxical. We thus attempted to provide an overview on the role of hydrophobicity in chaperone-like activity of ,-crystallin, the kind of evaluation done for the first time. iubmb Life, 58: 632 - 641, 2006 [source] A coordinated approach to cutaneous wound healing: vibrational microscopy and molecular biologyJOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 5b 2008K. L. Andrew Chan Abstract The repair of cutaneous wounds in the adult body involves a complex series of spatially and temporally organized processes to prevent infection and restore homeostasis. Three characteristic phases of wound repair (inflammation, proliferation including re-epithelialization and remodelling) overlap in time and space. We have utilized a human skin wound-healing model to correlate changes in genotype and pheno-type with infrared (IR) and confocal Raman spectroscopic images during the re-epithelialization of excisional wounds. The experimental protocols validated as IR images clearly delineate the keratin-rich migrating epithelial tongue from the collagen-rich wound bed. Multivariate statistical analysis of IR datasets acquired 6 days post-wounding reveal subtle spectral differences that map to distinct spatial distributions, which are correlated with immunofluorescent staining patterns of different keratin types. Images computed within collagen-rich regions expose complementary spatial patterns and identify elastin in the wound bed. The temporal sequence of events is explored through a comparison of gene array analysis with confocal Raman microscopy. Our approach demonstrates the feasibility of acquiring detailed molecular structure information from the various proteins and their subclasses involved in the wound-healing process. [source] Homocysteine induces metalloproteinase and shedding of ,-1 integrin in microvessel endothelial cells,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 1 2004Suresh Shastry Abstract Although studies have suggested microvessel endothelial cells (MVEC) activation and induction of matrix metalloproteinases (MMPs) by homocysteine (Hcy), the transduction mechanism leading to endothelial activation was unclear. We hypothesized that Hcy induced metalloproteinase and altered the levels of integrin in MVEC. MVEC from mouse brain were isolated and characterized by CD-31 (PECAM-1) FITC labeling. The MVEC were activated with different doses (6,40 ,M) of Hcy. The cultured-conditioned-medium was analyzed for MMP activity by gelatin gel-zymography. TIMP-1, -4, ,-1 integrin, and a disintegrin and metalloproteinase-12 (ADAM-12) were quantified by Western blot analysis. We used MVEC in cell culture to study the effect of increasing concentrations of Hcy upon the secretion of various proteins into the culture medium. MMP-9, ,-1 integrin, ADAM-12, and TIMP-1 were found in increased concentrations in the culture medium of Hcy-treated cells whereas TIMP-4 was decreased. We have shown that purified TIMP-4 blocked the increase of ,-1 integrin shedding in Hcy-treated cells. Interestingly, our results suggest that TIMP-1 and TIMP-4 function antagonistically in Hcy-induced signaling pathways. © 2004 Wiley-Liss, Inc. [source] Developmental change and function of chondroitin sulfate deposited around cerebellar Purkinje cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 2 2005Yumiko Shimazaki Abstract Chondroitin sulfate is a long sulfated polysaccharide with enormous structural heterogeneity that binds with various proteins, such as growth factors, in a structure-dependent manner. In this study, we analyzed the expression of chondroitin sulfate in the postnatally developing cerebellar cortex by using three monoclonal antibodies against chondroitin sulfate, MO-225, 2H6, and CS-56, which recognize different structural domains in this polysaccharide. During the first postnatal week, the patterns of immunohistochemical staining made by these antibodies were quite similar, and the molecular layer, the granule cell layer, and Bergmann glial fibers in the external granular layer were densely stained. After postnatal day 12 (P12), the expression of 2H6 epitopes was down-regulated in the molecular layer, and the expression of CS-56 epitopes in this layer was also reduced after P16. On the other hand, the strong expression of MO-225 epitopes, GlcA(2S),1,3GalNAc(6S) (D unit)-containing structures, remained until adulthood. These chondroitin sulfate epitopes were observed around Purkinje cells, including cell soma and dendrites. Detailed immunohistochemical analysis suggested that chondroitin sulfate was deposited between Purkinje cell surfaces and the processes of Bergmann glia. Furthermore, the amount of pleiotrophin, a heparin-binding growth factor, in the cultured cerebellar slices was remarkably diminished after treatment with chondroitinase ABC or D unit-rich chondroitin sulfate. With the previous findings that pleiotrophin binds to D unit-rich chondroitin sulfate, we suggest that the D-type structure is important for the signaling of pleiotrophin, which plays roles in Purkinje cell,Bergmann glia interaction, and that the structural changes of chondroitin sulfate regulate this signaling pathway. © 2005 Wiley-Liss, Inc. [source] Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamelJOURNAL OF ORAL REHABILITATION, Issue 2 2005A. M. KIELBASSA summary, The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 5·0; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L,1), mucin (577·5 mg L,1), immunoglobulin G (IgG) (46 mg L,1), casein isolated from bovine milk (1·2 g L,1)] or amino acid [l -Proline (7 mg L,1)] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 ,m) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 0·05; anova). Albumin, l -Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 0·01; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered. [source] Involvement of p38 mitogen-activated protein kinase pathway in honokiol-induced apoptosis in a human hepatoma cell line (hepG2)LIVER INTERNATIONAL, Issue 10 2008Junfang Deng Abstract Background: Honokiol has been known to have antitumour activity. This study was conducted to evaluate the antiproliferative potential of honokiol against the hepG2 heptocellular cell line and its mechanism of action. Methods: hepG2 cells were treated with honokiol of 0,40 ,g/ml concentration. The cytotoxic effect of honokiol was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The apoptosis was evaluated by flow cytometry. Western blots were used to analyse the expression of various proteins (procaspase-9, procaspase-3, cleaved caspase-3, cytochrome c, Bcl-2, Bax, Bad, Bcl-XL and p38). Results: Honokiol induced apoptosis with a decreased expression of procaspase-3 and -9 and an increased expression of active caspase-3. Exposure of hepG2 cells to honokiol resulted in the downregulation of Bcl-XL and Bcl-2 expression and the release of mitochondrial cytochrome c to the cytosol. In addition, honokiol activated the p38 mitogen-activated protein kinase (MAPK) pathway, and the inhibition of this pathway by SB203580 reduced honokiol-induced apoptosis and activation of caspase-3. Conclusion: Honokiol induces apoptosis of hepG2 human hepatocellular carcinoma cells through activation of the p38 MAPK pathway, and, in turn, activation of caspase-3. [source] Protein Sequences as Literature TextMACROMOLECULAR THEORY AND SIMULATIONS, Issue 5 2006Valentina V. Vasilevskaya Abstract Summary: We have performed analysis of protein sequences treating them as texts written in a "protein" language. We have shown that repeating patterns (words) of various lengths can be identified in these sequences. It was found that the maximum word lengths are different for proteins belonging to different classes; therefore, the corresponding values can be used to characterize the protein type. The suggested technique was first applied to analyze (decompose into words) normal (literature) texts written as a gapless symbolic sequence without spaces and punctuation marks. The tests using fiction, scientific, and popular scientific English texts proved the relative efficiency of the technique. Maximum word length for various proteins: ,fibrillar proteins, ,globular proteins, ,membrane proteins. [source] The RhaS activator controls the Erwinia chrysanthemi 3937 genes rhiN, rhiT and rhiE involved in rhamnogalacturonan catabolismMOLECULAR MICROBIOLOGY, Issue 5 2004Nicole Hugouvieux-Cotte-Pattat Summary Erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. The linear regions of pectin are composed of an acidic sugar, d -galacturonic acid. The ramified regions of pectin also include neutral sugars, and are rich in l -rhamnose residues. E. chrysanthemi is able to degrade these polysaccharides, polygalacturonate and rhamnogalacturonate. In E. chrysanthemi, the production of pectinases acting on linear regions is induced in the presence of polygalacturonate by a mechanism involving the repressor KdgR. The induction of the two adjacent E. chrysanthemi genes, designated rhiT and rhiN, is maximal after the simultaneous addition of both polygalacturonate and l -rhamnose. The rhiT product is homologous to the oligogalacturonide transporter TogT of E. chrysanthemi. The rhiN product is homologous to various proteins of unknown function, including a protein encoded by the plant-inducible locus picA of Agrobacterium tumefaciens. Both rhiT and rhiN are highly induced during plant infection. Various data suggest that RhiT and RhiN are involved in rhamnogalacturonate catabolism. RhiN is able to degrade the oligomers liberated by the rhamnogalacturonate lyase RhiE. The induction of the rhiTN operon in the presence of polygalacturonate results from control by the repressor KdgR. The additional induction of these genes by rhamnose is directly mediated by RhaS, a protein homologous to the activator of rhamnose catabolism in Escherichia coli. The virulence of an E. chrysanthemi rhaS mutant towards different host plants was clearly reduced. In this phytopathogenic bacterial species, RhaS positively regulates the transcription of the rhaBAD operon, involved in rhamnose catabolism, of the rhiE gene and of the rhiTN operon. The regulator RhaS plays a larger role in E. chrysanthemi than in other enterobacteria. Indeed, the RhaS control is not restricted to the catabolism of rhamnose but is extended to the degradation of plant polysaccharides that contain this sugar. [source] Protein Diffusion Probed by the Transient Grating Method with a New Type of Photochromic Molecule,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 4 2008Takeshi Eitoku A new type of photochromic molecule that can be used for diffusion coefficient (D) measurements of various proteins in solution is described. The absorption spectrum of this molecule is changed upon photoexcitation by the trans,cis isomerization reaction. Target proteins were labeled by this photochromic molecule in the dark and the translational motion of the proteins was detected by the transient grating (TG) method. The TG signal was simple enough to determine D accurately and was stable even for long-time irradiation by the laser light. The TG method using this probe molecule improves many drawbacks of the other techniques. [source] A novel [Ag(NH3)2]+ probe for chemiluminescent imaging detection of proteins after polyacrylamide gel electrophoresisPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 15 2007Xin Xiong Abstract The development of a novel [Ag(NH3)2]+ probe chemiluminescence (CL)-based imaging method for the detection of various proteins after PAGE is described. The detection is based upon the probe [Ag(NH3)2]+ catalyzing the CL reaction of the luminol,potassium persulfate system. The proposed method detects various proteins labeled by [Ag(NH3)2]+ and expands the application scope to SDS gels. It also detects proteins directly in polyacrylamide gels, without tedious transferring procedures. Furthermore, successful identification of proteins by peptide mass profiling using ionization MS was easily performed, and no pretreatments of gel prior to digestion are needed. Detection limits for standard marker proteins match CBB-R250 staining and the linear dynamic range is superior to CBB-R250 staining and silver staining. The CL imaging conditions, including luminescent reagents, silver ion concentration, the ammonia-controlled system and the washing reagents parameters have also been optimized. [source] Amyloid ,-Peptide(1-42) Contributes to the Oxidative Stress and Neurodegeneration Found in Alzheimer Disease BrainBRAIN PATHOLOGY, Issue 4 2004D. Allan Butterfield Oxidative stress is extensive in Alzheimer disease (AD) brain. Amyloid ,-peptide (1,42) has been shown to induce oxidative stress and neurotoxicity in vitro and in vivo. Genetic mutations that result in increased production of A,1,42 from amyloid precursor protein are associated with an early onset and accelerated pathology of AD. Consequently, A,1,42 has been proposed to play a central role in the pathogenesis of AD as a mediator of oxidative stress. In this review, we discuss the role of A,1,42 in the lipid peroxidation and protein oxidation evident in AD brain and the implications of such oxidative stress for the function of various proteins that we have identified as specifically oxidized in AD brain compared to control, using proteomics methods. Additionally, we discuss the critical role of methionine 35 in the oxidative stress and neurotoxic properties exhibited by A,1,42. [source] Reduction of cell cycle progression in human erythroid progenitor cells treated with tumour necrosis factor alpha occurs with reduced CDK6 and is partially reversed by CDK6 transductionBRITISH JOURNAL OF HAEMATOLOGY, Issue 6 2003Chunhua Dai Summary. Tumor necrosis factor , (TNF,) potently inhibits the in vitro growth of highly purified human d-6 erythroid colony forming cells (ECFC). Unlike the inhibitory effect of TNF, on other cells, including more immature ECFC, this antiproliferative effect of TNF, is not related to apoptosis because the d-6 cell descendants were morphologically normal, without apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labelling assay and without caspase activation by Western blots after TNF, treatment. TNF, did not appear to affect the cell cycle distribution, but the cell cycle duration was significantly longer in TNF,-treated cells. DNA synthesis was also significantly reduced by TNF,. Studies of various proteins that regulate the cell cycle showed that cyclin-dependent kinase 6 (CDK6) protein and mRNA levels were concomitantly decreased in the presence of TNF,, suggesting that inhibition of cell growth was related to reduced CDK6. To evaluate this, the CDK6 gene was transferred into ECFC using green fluorescence protein-retrovirus-mediated gene transfer. The results showed that the level of cell growth produced by TNF, was increased by 30% when the cells were transfected with CDK6. Therefore, the modification of cell cycle progression in the presence of TNF, through a reduction of CDK6 is an important mechanism in the TNF, inhibition of human ECFC expansion. [source] Recent Progress in Strategies for the Creation of Protein-Based Fluorescent BiosensorsCHEMBIOCHEM, Issue 16 2009Hangxiang Wang Abstract The creation of novel bioanalytical tools for the detection and monitoring of a range of important target substances and biological events in vivo and in vitro is a great challenge in chemical biology and biotechnology. Protein-based fluorescent biosensors,integrated devices that convert a molecular-recognition event to a fluorescent signal,have recently emerged as a powerful tool. As the recognition units various proteins that can specifically recognize and bind a variety of molecules of biological significance with high affinity are employed. For the transducer, fluorescent proteins, such as green fluorescent protein (GFP) or synthetic fluorophores, are mostly adopted. Recent progress in protein engineering and organic synthesis allows us to manipulate proteins genetically and/or chemically, and a library of such protein scaffolds has been significantly expanded by genome projects. In this review, we briefly describe the recent progress of protein-based fluorescent biosensors on the basis of their platform and construction strategy, which are primarily divided into the genetically encoded fluorescent biosensors and chemically constructed biosensors. [source] Rapid Matrix-Assisted Refolding of Histidine-Tagged ProteinsCHEMBIOCHEM, Issue 5 2009Tetyana Dashivets Abstract Matrix refolded: The formation of inclusion bodies, which are amorphous aggregates of misfolded insoluble protein, during recombinant protein expression, is one of the biggest bottlenecks in protein science. We report a stepwise, rational optimization procedure for refolding of insoluble proteins (see scheme). In comparison to refolding in-solution, this parallelized, matrix-assisted approach allows the refolding of various proteins in a fast and efficient manner. The formation of inclusion bodies (IBs),amorphous aggregates of misfolded insoluble protein,during recombinant protein expression, is still one of the biggest bottlenecks in protein science. We have developed and analyzed a rapid parallel approach for matrix-assisted refolding of recombinant His6 -tagged proteins. Efficiencies of matrix-assisted refolding were screened in a 96-well format. The developed methodology allowed the efficient refolding of five different test proteins, including monomeric and oligomeric proteins. Compared to refolding in-solution, the matrix-assisted refolding strategy proved equal or better for all five proteins tested. Interestingly, specifically oligomeric proteins displayed significantly higher levels of refolding compared to refolding in-solution. Mechanistically, matrix-assisted folding seems to differ from folding in-solution, as the reaction proceeds more rapidly and shows a remarkably different concentration dependence,it allows refolding at up to 1000-fold higher protein concentration than folding in-solution. [source] | ||||||||||||||||||||||