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Recognition Element (recognition + element)
Selected AbstractsMapping the Landscape of Potentially Primordial Informational Oligomers: Oligo-dipeptides Tagged with Orotic Acid Derivatives as Recognition Elements,ANGEWANDTE CHEMIE, Issue 43 2009Xuejun Zhang Dr. Vorhersage erlaubt: Die Basenpaarungseigenschaften von Oligodipeptiden, die mit Orotsäure und deren 2,4-Diamino-Derivat konjugiert wurden (siehe Struktur), sind im Einklang mit zuvor beobachteten Korrelationen zwischen den ,pKS -Werten komplementärer Basen und ihrem Paarbildungsvermögen. Die Ergebnisse begründen, dass das Basenpaarungsvermögen eines Erkennungselements aus dessen pKS -Wert und dem pH-Wert des Mediums abgeschätzt werden kann. [source] Peptide Modified Electrodes as Electrochemical Metal Ion SensorsELECTROANALYSIS, Issue 15 2006Edith Chow Abstract Sensors for the detection of metal ions are of considerable importance for enabling the monitoring of environmental samples for metal ion contamination directly in the field. This review outlines the use of peptides and amino acids as the recognition element of electrochemical sensors for metal ion detection. Initially the complexation of metals by peptides is discussed followed by the immobilization of peptides on electrode surfaces. Subsequently, the application of peptide modified electrodes for detecting metals is reviewed and finally challenges and future prospects are outlined. [source] Vapor-Phase Deposition of Monofunctional Alkoxysilanes for Sub-Nanometer-Level Biointerfacing on Silicon Oxide SurfacesADVANCED FUNCTIONAL MATERIALS, Issue 1 2010Brian Dorvel Abstract Improving the performance and lowering the analyte detection limits of optical and electronic biosensors is essential for advancing wide ranging applications in diagnostics and drug discovery. Most sensing methods require direct linkage of a recognition element and a sensor, which is commonly accomplished through an organic monolayer interface. Alkoxyorganosilanes are typically used to prepare sensor surfaces on dielectric oxides. However, many silanes lead to roughened or thick interfaces that degrade device sensitivity. Here, controlled vapor phase deposition of monoalkoxysilanes is found to lead to monolayers resistant to elevated temperatures and extreme pH conditions. The formation of high density, subnanometer monolayers is demonstrated by ellipsometry, XPS, and AFM. The uniform attachment of these monofunctional silanes to such biosensing platforms as microarrays, field effect devices, and the formation of surface enhanced Raman spectroscopy substrates is demonstrated. The advantages of using this silane deposition protocol for the above technologies are also discussed. [source] Transcription factor NF-,B activation after in vivo perforant path LTP in mouse hippocampusHIPPOCAMPUS, Issue 6 2004Ramiro Freudenthal Abstract There is increasing evidence that transcription factors (TFs) play a critical role in maintaining later phases of hippocampal long-term potentiation (LTP). We have been led to study the role in synaptic plasticity of the powerful, yet generally unheralded, NF-,B TF because it may serve as both a signaling molecule after its activation at the synapse and then a transcription initiator upon reaching the nucleus. In the present study, we show that LTP activates NF-,B in the intact mouse hippocampus. Mice were sacrificed 15 min after one of three treatments: tetanization (high-frequency stimulation [HFS]), low-frequency stimulation (LFS), or no stimulated control animals (CT). In a first study, nuclear NF-,B activity from hippocampus was estimated by electrophoretic mobility shift assays (EMSAs). A higher level of hippocampal TF binding to the NF-,B recognition element was found in the HFS group compared with LFS or CT. In a second study, NF-,B activity was evaluated by immunohistochemistry with a specific antibody that recognizes the activated form of NF-,B. This antibody binds to the exposed nuclear location sequence on the p65 subunit of NF-,B consequent to its dissociation from the inhibitory I,B molecule. In the four subfields of hippocampus examined,granule cell layer, hilus of the dentate gyrus, CA3 and CA1 pyramidal fields of the hippocampal gyrus,the highest levels of activated NF-,B, statistically significant in all cases were found after HFS. In certain comparisons, LFS animals also showed significant elevation with respect to CT. These results support the role of NF-,B as part of the synaptic signaling and transcriptional regulation mechanism required in long-term plasticity, emphasizing the combinatorial nature of TF function. © 2004 Wiley-Liss, Inc. [source] A ,-amino acid modified heptapeptide containing a designed recognition element disrupts fibrillization of the amyloid ,-peptideJOURNAL OF PEPTIDE SCIENCE, Issue 9 2010Valeria Castelletto Abstract We study the complex formation of a peptide ,A,AKLVFF, previously developed by our group, with A,(1,42) in aqueous solution. Circular dichroism spectroscopy is used to probe the interactions between ,A,AKLVFF and A,(1,42), and to study the secondary structure of the species in solution. Thioflavin T fluorescence spectroscopy shows that the population of fibers is higher in ,A,AKLVFF/A,(1,42) mixtures compared to pure A,(1,42) solutions. TEM and cryo-TEM demonstrate that co-incubation of ,A,AKLVFF with A,(1,42) causes the formation of extended dense networks of branched fibrils, very different from the straight fibrils observed for A,(1,42) alone. Neurotoxicity assays show that although ,A,AKLVFF alters the fibrillization of A,(1,42), it does not decrease the neurotoxicity, which suggests that toxic oligomeric A,(1,42) species are still present in the ,A,AKLVFF/A,(1,42) mixtures. Our results show that our designed peptide binds to A,(1,42) and changes the amyloid fibril morphology. This is shown to not necessarily translate into reduced toxicity. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. [source] Carcinogenesis and transcriptional regulation through Maf recognition elementsCANCER SCIENCE, Issue 2 2007Hozumi Motohashi Many studies on carcinogenesis carried out early in the last century are united on the consensus that cancer is a genetic disease. Cancer cells typically display gene dysfunction and endogenous or exogenous insults resulting in gene dysfunction are often carcinogenic. Recent advances in stem cell biology added the new concept that cancer originates from a single cancer-initiating cell. To understand the molecular basis of carcinogenesis from the beginning to the full acquirement of malignancy, factors concerned with carcinogenesis were categorized into three groups: those guarding and stabilizing genomes, those regulating cell proliferation, and those conferring resistance to various micro-environmental stresses. One example of particular interest is the Keap1-Nrf2 system since, according to recent studies, it has turned out to be ambivalent. Nrf2 heterodimerizes with small Maf protein to strongly activate transcription through the Maf recognition element (MARE) and Keap1 is an inhibitory regulator of Nrf2. The genes regulated by Nrf2 are very important for cellular protection of the genome from xenobiotic and oxidative stresses and, consequently, for preventing carcinogenesis. This implies that enhancing Nrf2 activity is a promising method for thwarting cancer. On the contrary, the constitutive activation of Nrf2 due to mutations in the keap1 gene is characteristically observed in lung cancer cells, suggesting that induced expression of Nrf2 target genes favors the prevalence of cancer cells. (Cancer Sci 2007; 98: 135,139) [source] Structured Nucleic Acid Probes for Electrochemical DevicesELECTROANALYSIS, Issue 19 2009Rebeca Miranda-Castro Abstract The use of nucleic acid with a specific sequence and a highly ordered secondary structure such as hairpins, quadruplexes and pseudoknots as biological recognition elements and switches in biosensors is rapidly increasing because of their improved features (e.g. selectivity) when compared with the traditional linear probes. Owing to the novelty, a critical outlook of their characteristics and a compilation of the latest advances are lacking. This article describes the potential of those nucleic acids probes whose molecular recognition ability relies on a conformational change (e.g. folding/unfolding mechanism) in electrochemical sensing. It provides an overview of the toolbox of assays using these probes for genosensors and aptasensors, highlighting its performance characteristics and the prospects and challenges for biosensor design. [source] Uniformly Nucleobase-Functionalized ,-Peptide Helices: Watson,Crick Pairing or Nonspecific AggregationEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 33 2007Angelina Weiß Abstract The organization and architecture of helices is fundamental in folding of protein tertiary structures. Therefore, stable ,-peptide helices are used as models for the selective organization of secondary structures. Nucleobases are already established as recognition elements to organize two ,-peptide helices in antiparallel orientation. The investigation of ,-peptide helices uniformly functionalized with one type of nucleobases provided further insight in the recognition mode and requirements for specific interaction within the linear and very rigid helical backbone topology. Specific helix interaction based on base pair recognition is predominant as soon as Watson,Crick pairing is allowed. If the hydrogen bonding donor/acceptor pattern prohibits the Watson,Crick geometry, a quite stable nonspecific interaction was found based on aromatic interactions or on a nonspecific hydrogen bonding network. The latter aggregation was also confirmed with tyrosine side chains.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Functionalization of Gold and Glass Surfaces with Magnetic Nanoparticles Using Biomolecular InteractionsBIOTECHNOLOGY PROGRESS, Issue 1 2006Bala G. Nidumolu Advances in nanotechnology have enabled the production and characterization of magnetic particles with nanometer-sized features that can be functionalized with biological recognition elements for numerous applications in biotechnology. In the present study, the synthesis of and interactions between self-assembled monolayers (SAMs) on gold and glass surfaces and functionalized magnetic nanoparticles have been characterized. Immobilization of 10,15 nm streptavidin-functionalized nanoparticles to biotinylated gold and glass surfaces was achieved by the strong interactions between biotin and streptavidin. Fluorescent streptavidin-functionalized nanoparticles, biotinylated surfaces, and combinations of the two were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electron and fluorescent microscopy to confirm that little or no functionalization occurred in nonbiotinylated regions of the gold and glass surfaces compared to the biotinylated sites. Together these techniques have potential use in studying the modification and behavior of functionalized nanoparticles on surfaces in biosensing and other applications. [source] Carcinogenesis and transcriptional regulation through Maf recognition elementsCANCER SCIENCE, Issue 2 2007Hozumi Motohashi Many studies on carcinogenesis carried out early in the last century are united on the consensus that cancer is a genetic disease. Cancer cells typically display gene dysfunction and endogenous or exogenous insults resulting in gene dysfunction are often carcinogenic. Recent advances in stem cell biology added the new concept that cancer originates from a single cancer-initiating cell. To understand the molecular basis of carcinogenesis from the beginning to the full acquirement of malignancy, factors concerned with carcinogenesis were categorized into three groups: those guarding and stabilizing genomes, those regulating cell proliferation, and those conferring resistance to various micro-environmental stresses. One example of particular interest is the Keap1-Nrf2 system since, according to recent studies, it has turned out to be ambivalent. Nrf2 heterodimerizes with small Maf protein to strongly activate transcription through the Maf recognition element (MARE) and Keap1 is an inhibitory regulator of Nrf2. The genes regulated by Nrf2 are very important for cellular protection of the genome from xenobiotic and oxidative stresses and, consequently, for preventing carcinogenesis. This implies that enhancing Nrf2 activity is a promising method for thwarting cancer. On the contrary, the constitutive activation of Nrf2 due to mutations in the keap1 gene is characteristically observed in lung cancer cells, suggesting that induced expression of Nrf2 target genes favors the prevalence of cancer cells. (Cancer Sci 2007; 98: 135,139) [source] | |||||||||||||