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Synthesis Protocol (synthesis + protocol)
Selected AbstractsA Practical and Efficient Approach to PNA Monomers Compatible with Fmoc-Mediated Solid-Phase Synthesis Protocols,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2008Andrea Porcheddu Abstract A straightforward synthesis of orthogonally protected PNA monomers is described. Protected aminoethylglycine (Aeg) monomers were efficiently prepared by reductive amination of N -Fmoc-glycinaldehyde with glycine methyl ester and the subsequent acylation of the free amine with N -bis-Boc-protected nucleobase acetic acids. The exocyclic amine group of the nucleobases, including the notoriously difficult-to-protect guanine nucleobase, was protected with a bis-Boc carbamate group; this increased the solubility of the nucleobases in the most common organic solvents. The current protocol allows all Aeg monomers to be prepared on both the micro- and macroscale, which avoids or minimizes the use of toxic reagents or solvents, and moreover, cheap starting materials are used. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Functional Chromium Wheel-Based Hybrid Organic,Inorganic Materials for Dielectric ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Vito Di Noto Abstract The first example of organic,inorganic hybrid materials based on the embedding of a chromium,nickel wheel cluster {[(n-C3H7)2NH2]- [Cr7NiF8(O2C4H5)16]} (Cr7Ni) into poly(methyl methacrylate) (PMMA) and the characterization of the dielectric properties of the obtained material is described. By an optimized copolymerization of the methacrylate-functionalized chromium,nickel wheel with methyl methacrylate in a cluster/monomer 1:200 molar mixture, a homogeneous hybrid material CrNi_MMA200 is obtained. The electrical responses of the non-doped PMMA and of the hybrid material were studied by broadband dielectric spectroscopy (BDS) from 0.01,Hz to 10,MHz and over the temperature range of 5,115,°C. The permittivity profiles reveal two relaxation peaks in the materials, which correspond to the , and , relaxation modes of the PMMA matrix. The position of these modes shifts toward higher frequencies as temperature increases. BDS is a powerful tool revealing the intimate miscibility of the various components of the hybrid material, thus indicating that, on a molecular scale, the material proposed is a homogeneous system. Finally, a value of the dielectric constant of 2.9 at 25,°C and 1,kHz is determined. This value is noticeably lower than the value of 3.2 obtained for pristine PMMA prepared following the same synthesis protocol. Thus, these results classify the hybrid CrNi_MMA200 as an appealing starting material for the development of dielectric polymeric layers for the development of innovative capacitors, transistors, and other microelectronic devices. The vibrational properties of the hybrid materials are investigated by Fourier-transform infrared (FT-IR) and Raman spectroscopy, whereas the thermal behavior is analyzed by thermogravimetric analysis (TGA). Swelling experiments are used to qualitatively evaluate the crosslinking density of the hybrid materials. The integrity of the wheels once embedded in the macromolecular backbone is confirmed by extended X-ray absorption fine structure (EXAFS) and electron spin resonance (EPR) spectroscopic measurements. [source] Pyrosequencing for detection of mutations in the connexin 26 (GJB2) and mitochondrial 12S RNA (MTRNR1) genes associated with hereditary hearing loss,HUMAN MUTATION, Issue 4 2002Alessandro Ferraris Abstract Hereditary hearing loss (HHL) is one of the most common congenital disorders and is highly heterogeneous. Mutations in the connexin 26 (CX26) gene (GJB2) account for about 20% of all cases of childhood deafness, and approach 50% in documented recessive cases of non-syndromic hearing loss. In addition, a single mitochondrial DNA mutation, mt1555A>G, in the 12S rRNA gene (MTRNR1), is associated with familial cases of progressive deafness. Effective screening of populations for HHL necessitates rapid assessment of several of these potential mutation sites. Pyrosequencing links a DNA synthesis protocol for determining sequence to an enzyme cascade that generates light whenever pyrophosphate is released during primer strand elongation. We assessed the ability of Pyrosequencing to detect common mutations causing HHL. Detection of the most common CX26 mutations in individuals of Caucasian (35delG), Ashkenazi (167delT), and Asian (235delC, V37I) descent was confirmed by Pyrosequencing. A total of 41 different mutations in the CX26 gene and the mitochondrial mt1555A>G mutation were confirmed. Genotyping of up to six different adjacent mutations was achieved, including simultaneous detection of 35delG and 167delT. Accurate and reproducible results were achieved taking advantage of assay flexibility and experimental conditions easily optimized for a high degree of standardization and cost-effectiveness. The standardized sample preparation steps, including target amplification by PCR and preparation of single-stranded template combined with automated sequence reaction and automated genotype scoring, positions this approach as a potentially high throughput platform for SNP/mutation genotyping in a clinical laboratory setting. Hum Mutat 20:312,320, 2002. © 2002 Wiley-Liss, Inc. [source] Solid-phase synthesis of C -terminally modified peptidesJOURNAL OF PEPTIDE SCIENCE, Issue 11 2006Hefziba T. Ten Brink Abstract In this paper, a straightforward and generic protocol is presented to label the C -terminus of a peptide with any desired moiety that is functionalized with a primary amine. Amine-functional molecules included are polymers (useful for hybrid polymers), long alkyl chains (used in peptide amphiphiles and stabilization of peptides), propargyl amine and azido propyl-amine (desirable for ,click' chemistry), dansyl amine (fluorescent labeling of peptides) and crown ethers (peptide switches/hybrids). In the first part of the procedure, the primary amine is attached to an aldehyde-functional resin via reductive amination. To the secondary amine that is produced, an amino acid sequence is coupled via a standard solid-phase peptide synthesis protocol. Since one procedure can be applied for any given amine-functional moiety, a robust method for C -terminal peptide labeling is obtained. Copyright © 2006 European Peptide Society and John Wiley & Sons, Ltd. [source] Isolation of polymorphic microsatellite markers from the malaria vector Anopheles darlingiMOLECULAR ECOLOGY RESOURCES, Issue 4 2001Jan E. Conn Abstract High molecular weight DNA was extracted from the primary Neotropical malaria vector, Anopheles darlingi from Capanema, Pará, Brazil, to create a small insert genomic library, and then a phagemid library. Enriched sublibraries were constructed from the phagemid library using a microsatellite oligo primed second strand synthesis protocol. The resulting 242 760 individual clones were screened. The mean clone size of the positive clones was 302 bp. Flanking primers were designed for each suitable microsatellite sequence. Eight polymorphic loci were optimized and characterized. The allele size ranges are based on 253 samples of A. darlingi from eastern Amazonian and central Brazil. [source] Synthesis and biological evaluation of destruxin A and related analogsCHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2001T. Ast Abstract: This report describes the development of an efficient solid-phase synthesis protocol and adaptation of reported solution phase procedures for the synthesis of the cyclic depsihexapeptide destruxin A and related analogs. The solid-phase method described is based on standard Fmoc peptide chemistry, including a new synthetic method for the assembly of the depsi bond-containing unit. In order to select analogs of destruxin A for synthesis and evaluation of insecticidal activity, the work of Hellberg et al., describing a set of Z -descriptors for amino acid side-chains comparing their physicochemical properties, was utilized. Destruxin A and 27 different analogs with structural variations in four residues were synthesized and insecticidal activity was evaluated via injections into tobacco budworm (Heliothis virescens) larvae. Several destruxin A analogs were found to be at least as potent as the native compound. [source] Divergent and Linear Solid-Phase Synthesis of PNA Containing Thiazole Orange as Artificial BaseEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2005Dilip V. Jarikote Abstract Fluorescent nucleobase surrogates provide nucleic acids with interesting properties. We have recently introduced thiazole orange as base surrogate into PNA and found that the so-called FIT (Forced Intercalation of Thiazole orange) PNA probes signal hybridization by enhancements of fluorescence. Common approaches of modifying nucleobases or introducing nucleobase surrogates draw upon the usage of monomer building blocks that have been synthesized in solution phase. The need to prefabricate a base-modified building block can hold up progress if several base modifications or base surrogates are to be evaluated. Herein, a method for divergent solid-phase synthesis is presented that serves the purpose to facilitate the screening for base surrogates that fluoresce upon hybridization. An Fmoc/Aloc-protected submonomer allowed the application of commonly used Fmoc-based solid-phase synthesis protocols while removal of the fully orthogonal Aloc group enabled the on-resin introduction of base surrogates after the linear chain assembly had been completed. The divergent solid-phase synthesis strategy is automatable, gives overall yields matching those of linear solid-phase synthesis and, most importantly, provides rapid access to any kind of base-modified PNA. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] N -Tetrachlorophthaloyl (TCP) Protection for Solid-Phase Peptide SynthesisEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2004Esther Cros Abstract The N -tetrachlorophthaloyl-(TCP-)amino protecting group has been evaluated for use in solid-phase peptide synthesis. The TCP group was unaffected by exposure to either piperidine or N,N -diisopropylethylamine (DIEA), which suggests compatibility with both Fmoc and Boc solid-phase synthesis protocols. Quantitative TCP removal was achieved by treatment with hydrazine/DMF (3:17) at 35 °C for 30 min or with ethylenediamine/DMF (1:200) at 50 °C for 30 min. Several C-terminal peptide amides were synthesized successfully by following protocols that use hydrazine/DMF (3:17) at 40 °C for 1 h for repetitive deprotection. Treatment of TCP-amines with methylamine or with diamines did not give the corresponding amines (deprotected), but rather the appropriate N,N, -disubstituted tetrachlorophthalamides, which corresponds to a single ring-opening step. This observation was harnessed to prepare linear and macrocyclic peptide,arene hybrids based on the mild reaction of the parent TCP compound with 1,3-diaminopropane/DMF (1:49) at 25 °C for 5 min. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Microreactor Array Assembly, Designed for Diversity Oriented Synthesis Using a Multiple Core Structure Library on Solid SupportMOLECULAR INFORMATICS, Issue 11 2006Alexander Groß Abstract The application of spatially encoded principles in solid phase combinatorial synthesis requires no chemical or physical coding strategies. The resulting products are encoded by their position inside the array and their synthesis history. The advantages of microreactor arrays for solid phase synthesis as one of the embodiments in the field of microreaction technology are discussed. Here, we review the reactor design, necessary process steps, and a strategy for the diversity oriented array synthesis. In particular, the glass-made microreactor and its assembly for 1563 parallel solid phase reactions, which can be performed at temperatures up to 120,°C, are described. Bead loading and liquid handling steps were adapted to this array. The production of large libraries demands suitable synthesis protocols and building blocks. The optimization of appropriate synthesis conditions is a time-consuming process. A multiple core structure library approach for the efficient synthesis of diverse heterocyclic libraries is described. The aim of this work was to prove the feasibility of the glass-microreaction array for massive parallel library synthesis. [source] | |||||||||||||