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Results 251 - 300 of 2117
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Yamamoto Tetsuya - - 2012
The palladium-catalyzed cross-coupling of chlorotrifluoroethylene and arylboronic acids proceeds in the presence of a base and H(2)O to provide α,β,β-trifluorostyrene derivatives in satisfactory yields.
Bergfeld Anne K - - 2012
The outermost positions of mammalian cell-surface glycans are predominantly occupied by the sialic acids N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc). To date, hydroxylation of CMP-Neu5Ac resulting in the conversion into CMP-Neu5Gc is the only known enzymatic reaction in mammals to synthesize a monosaccharide carrying an N-glycolyl group. In our ...
Pellegrino Sara - - 2012
A very efficient synthesis of orthogonally protected 1H-azepine-4-amino-4-carboxylic acid, abbreviated as Azn, a conformationally restricted analogue of ornithine, was realized. It was obtained on a gram scale in good overall yield in five steps, three of which did not require isolation of the intermediates, starting from the readily available 1-amino-4-oxo-cyclohexane-4-carboxylic ...
Louwagie Mathilde - - 2012
Accurate quantification of pure peptides and proteins is essential for biotechnology, clinical chemistry, proteomics and systems biology. The reference method to quantify peptides and proteins is amino acid analysis (AAA). This consists in an acidic hydrolysis followed by chromatographic separation and spectrophotometric detection of amino acids. Although widely used, this ...
He Jun - - 2012
By combining a novel chiral amino-acid surfactant containing an acryloyl amide tail, a carbamate linker, and a leucine headgroup of different chain lengths with a conventional cross-linker and a polymerization technique, a new "one-pot" synthesis for the generation of amino-acid based polymeric monolith is realized. The method promises to open ...
Oh Jung Min - - 2012
Non-alcoholic steatohepatitis (NASH) is an increasingly common cause of chronic liver disease; however, no specific pharmacologic therapy has been shown to be effective in its treatment. The present study was designed to develop an experimental cell culture model of NASH using four kinds of fatty acids-palmitic acid (PA), stearic acid ...
Sleszyńska Małgorzata - - 2012
In the current work we present some pharmacological characteristics of ten new analogues of bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) modified in the N-terminal part of the molecule with a variety of acyl substituents. Of the many acylating agents used previously with B(2) receptor antagonists, the following residues were chosen: 1-adamantaneacetic acid (Aaa), 1-adamantanecarboxylic ...
Marco-Urrea Ernest - - 2012
Dehalococcoides species are key players in the anaerobic transformation of halogenated solvents at contaminated sites. Here, we analyze isotopologue distributions in amino acid pools from peptides of Dehalococcoides strain CBDB1 after incubation with (13)C-labeled acetate or bicarbonate as a carbon source. The resulting data were interpreted with regard to genome ...
Smith Tekla D - - 2012
Gap junction channels composed of connexins connect cells, allowing intercellular communication. Their cellular assembly involves a unique quality-control pathway. Some connexins [including connexin43 (Cx43) and Cx46] oligomerize in the trans-Golgi network following export of stabilized monomers from the endoplasmic reticulum (ER). In contrast, other connexins (e.g., Cx32) oligomerize early in ...
Möller Heinz - - 2012
A biosynthetic method using a synthetic C4-modified mannosamine derivative provides the previously inaccessible C7 modifications of sialic acids in living cells. S. Hinderlich, C. P. R. Hackenberger, and co-workers also show in their Communication (10.1002/anie.201108809) that their synthetic mannosamine derivative could label the membrane-associated glycoproteins of live animals. The picture ...
Qian Wenjian W Chemical Biology Laboratory, Frederick National Laboratory for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, - - 2013
Protein-protein interactions (PPIs) mediated by the polo-box domain (PBD) of polo-like kinase 1 (Plk1) serve important roles in cell proliferation. Critical elements in the high affinity recognition of peptides and proteins by PBD are derived from pThr/pSer-residues in the binding ligands. However, there has been little examination of pThr/pSer mimetics ...
Lin Brian F - - 2012
GALA is a pH-responsive, membrane-perturbing peptide designed to fold from a random coil at physiological pH to an amphipathic α-helix under mildly acidic conditions. Due to its pH-activated function, GALA has been sought-after as a component of intracellular drug delivery systems that could actively propel endosomal escape. In this study, ...
Hou Hu - - 2012
BACKGROUND: Immunomodulatory peptides can enhance body immunity. There have been few systematic investigations on preparing immunomodulatory peptides from Alaska pollock frame. The aim of this study was to obtain such peptides from Alaska pollock frame and determine their properties. RESULTS: Trypsin protein hydrolysate (TPH) significantly enhanced the proliferation of spleen ...
Kalhan Satish C - - 2012
Serine is generally classified as a nutritionally nonessential (dispensable) amino acid, but metabolically, serine is indispensible and plays an essential role in several cellular processes. Serine is the major source of one-carbon units for methylation reactions that occur via the generation of S-adenosylmethionine. The regulation of serine metabolism in mammalian ...
Shao Naimin - - 2012
High-throughput screening of dendrimer-binding drugs is essential for the design and optimization of dendrimer-based drug delivery systems. In this study, pulsed gradient spin echo (PGSE) NMR was used for fast screening dendrimer-binding compounds using common amino acids as a screening pool. Diffusion coefficients of the amino acids before and after ...
Dhavale Dhruva - - 2012
BACKGROUND: Amyloid-beta peptide (Aβ) is the main constituent of senile plaques and is implicated in the pathogenesis of Alzheimer's disease (AD). To that end, agents which either sequester Aβ or interfere with Aβ interaction/binding to cells have been investigated as a means to reduce the pathological effects of Aβ. METHODS: ...
Hata Takeshi - - 2012
When alkenynedioic acid derivatives were treated with a Grignard reagent, tandem cyclization and the incorporation of two molecules of the Grignard reagent occurred to give stereodefined bicyclo[4.2.0]octenols via four nucleophilic additions.
Rademacher Christoph C Departments of Chemical Physiology and Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, - - 2012
Sialic-acid-binding immunoglobulin-like lectins (Siglecs) are a family of transmembrane receptors that are well documented to play roles in regulation of innate and adaptive immune responses. To see whether the features that define the molecular recognition of sialic acid were found in other sialic-acid-binding proteins, we analyzed 127 structures with bound ...
Gredičak Matija - - 2012
Enediyne-peptide conjugates were designed with the aim to inhibit aminopeptidase N, a widespread ectoenzyme with a variety of functions, like protein digestion, inactivation of cytokines in the immune system and endogenous opioid peptides in the central nervous system. Enediyne moiety was embedded within the 12-membered ring with hydrophobic amino acid ...
Sengoku Tetsuya - - 2012
For the efficient approach to medicinally important alpha-branched 3-acyltetramic acids, the key reaction of O- to C- acyl rearrangement using alpha-amino acids-derived 4-O-acyltetramic acids was extensively examined in the presence of various metal salts. Use of CaCl2 or NaI dramatically changed the results in the reaction efficiency and rapidly brought ...
Zervosen Astrid - - 2012
In response to the widespread use of β-lactam antibiotics bacteria have evolved drug resistance mechanisms that include the production of resistant Penicillin Binding Proteins (PBPs). Boronic acids are potent β-lactamase inhibitors and have been shown to display some specificity for soluble transpeptidases and PBPs, but their potential as inhibitors of ...
Qian Jiang - - 2012
β-ketoesters are robust probes for labeling sulfenic acid (-SOH) proteins allowing quantitative cleavage of the tag for improved analysis of the labeled peptides by MS.
Kamthan Mohan - - 2012
Candida albicans is a life threatening polymorphic pathogen for immunocompromised patients, causing superficial as well as invasive systemic diseases. The mucosal membranes of the host, which are the primary sites of its infection, are rich in amino sugars like N-acetylglucosamine (GlcNAc). GlcNAc is also one of the potent inducers of ...
Calder Philip C - - 2012
Inflammation plays a key role in many common conditions and diseases. Fatty acids can influence inflammation through a variety of mechanisms acting from the membrane to the nucleus. They act through cell surface and intracellular receptors that control inflammatory cell signalling and gene expression patterns. Modifications of inflammatory cell membrane ...
Clausen Jacob Dahlqvist - - 2012
Diamino acids are commonly found in bioactive compounds, yet only few are commercially available as building blocks for solid-phase peptide synthesis. In the present work a convenient, inexpensive route to multiple-charged amino acid building blocks with varying degree of hydrophobicity was developed. A versatile solid-phase protocol leading to selectively protected ...
Seo Young-Man - - 2012
A deracemization method was developed to generate optically pure l-homoalanine from racemic homoalanine using d-amino acid oxidase and ω-transaminase. A whole cell reaction using a biphasic system converted 500 mM racemic homoalanine to 485 mM l-homoalanine (>99% ee).
Monteiro Luís S - - 2012
Recently we reported the use of a sequence of alkylation and dehydration methodologies to obtain N-ethyl-α, β-dehydroamino acid derivatives. The application of this N-alkylation procedure to several methyl esters of β,β-dibromo and β-bromo, β-substituted dehydroamino acids protected with standard amine protecting groups was subsequently reported. The corresponding N-ethyl, β-bromo dehydroamino ...
Turcotte Stéphane - - 2012
N-Aminosulfamides are peptidomimetics in which the C(α)H and the carbonyl of an amino acid residue are both respectively replaced by a nitrogen atom and a sulfonyl group. Aza-sulfurylglycinyl tripeptide analogs were effectively synthesized from amino acid building blocks by condensations of N-protected amino hydrazides and p-nitrophenylsulfamidate esters. The installation of ...
Gajda Anna D - - 2012
Aminopeptidases are proteolytic enzymes that remove one amino acid at a time from N-terminus of peptidic substrates. In plants, inhibitors of aminopeptidases can find potential applications in agriculture as herbicides. In this report we have used a library of fluorogenic derivatives of natural and unnatural amino acids for substrate specificity ...
Raffy Quentin - - 2012
Radical migration between aliphatic amino acid side chains can occur in solution and intramolecularly in peptides. The kinetic constant of the hydrogen transfer reaction was measured by using competition kinetics, and the half-life as well as the distance that a radical can move within a protein was calculated.
Pellicciari Roberto R Dipartimento di Chimica e Tecnologia del Farmaco, Università di Perugia , Via del Liceo 1, 06123 Perugia, - - 2012
Grounding on our former 3D QSAR studies, a knowledge-based screen of natural bile acids from diverse animal species has led to the identification of avicholic acid as a selective but weak TGR5 agonist. Chemical modifications of this compound resulted in the disclosure of 6α-ethyl-16-epi-avicholic acid that shows enhanced potency at ...
Ilisz István - - 2012
Amino acids are essential for life, and have many functions in metabolism. One particularly important function is to serve as the building blocks of peptides and proteins, giving rise to complex three dimensional structures through disulfide bonds or crosslinked amino acids. Peptides are frequently cyclic and contain protein as well ...
Saladino Raffaele - - 2012
The key role of proteins and amino acids in the structure and function of living matter has stimulated extensive studies. Modified amino acids with enhanced biological activity, proteolitic stability and bioavailability are of increasing interest in protein design and engineering as drug candidates. In the last few years, several efforts ...
André Christophe - - 2012
In order to investigate the ability of the (S)-aminobicyclo[2.2.2]octane-2-carboxylic acid 1 (H-(S)-ABOC-OH) to induce reverse turns into peptides, two model tripeptides, in which this bicyclic unit was incorporated into the second position, were synthesized and analyzed by FT-IR, CD, NMR, and X-ray studies.
Raychaudhuri Soumya S Division of Genetics, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA. - - 2012
The genetic association of the major histocompatibility complex (MHC) to rheumatoid arthritis risk has commonly been attributed to alleles in HLA-DRB1. However, debate persists about the identity of the causal variants in HLA-DRB1 and the presence of independent effects elsewhere in the MHC. Using existing genome-wide SNP data in 5,018 ...
Boeckx Bram - - 2012
Within the structure determination task for peptides, which is of large interest due to the relation between structure and functionality, infrared spectra can provide detailed information on the conformational behavior. The conformational landscape of N-acetylgycine has been studied by a combined theoretical and matrix-isolation FT-IR study. The acetylation simulates an ...
Varisco Brian M BM Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH 45229, USA. - - 2012
Thy-1 is a glycosylphosphytidylinositol-linked cell-surface glycoprotein present on a subset of lung fibroblasts, which plays an important role in postnatal alveolarization. In the present study, we define the role of Thy-1 in pulmonary lipofibroblast differentiation and in the regulation of lipid homeostasis via peroxisome proliferator-activated receptor-γ (PPARγ). Thy-1 was associated ...
Brown Robert A - - 2012
Peptide helices containing L-amino acids are typically right-handed. Exceptions are peptide helices containing the achiral amino acids 2-aminoisobutyric acid and glycine with a single chiral amino acid at the N terminus. These helices are left-handed when the N-terminal residue is a common tertiary proteinogenic amino acid, such as L-valine, but right-handed ...
Zhao Yue - - 2012
Lipopeptide is one of the most important biosurfactants. The content of each isoform of a lipopeptide is crucial to the study of the properties of metabolites as well as the biological and biochemical characters of microbes. However, this information has not been accurately provided by the current analysis method. A ...
Su Chun-Hung - - 2012
[This corrects the article on p. e30617 in vol. 7.].
Jusakul Apinya - - 2012
Bile acids are implicated as aetiological factors in many types of gastrointestinal tract cancer including cholangiocarcinoma (CCA). Alterations in bile acid concentrations may affect the pathogenesis of these different types of cancer. Our aim was to determine the bile acid profile in gallbladder bile from patients who underwent liver resection. ...
Förster Charlotte - - 2012
"Locked nucleic acids" (LNAs) belong to the backbone-modified nucleic acid family. The 2'-O,4'-C-methylene-β-D-ribofuranose nucleotides are used for single or multiple substitutions in RNA molecules and thereby introduce enhanced bio- and thermostability. This renders LNAs powerful tools for diagnostic and therapeutic applications. RNA molecules maintain the overall canonical A-type conformation upon ...
Pattni Sanjeev S - - 2012
Increased colonic bile acids can cause chronic diarrhea. Bile acid diarrhea (BAD) is treatable by sequestrants, and may be secondary to ileal disease or primary BAD. It is underdiagnosed, partly because the selenium-75-homocholic acid taurine (SeHCAT) retention test is not available in many countries, and is underutilized in others. Serum ...
Döring Barbara - - 2012
The SLC10 family represents seven genes containing 1-12 exons that encode proteins in humans with sequence lengths of 348-477 amino acids. Although termed solute carriers (SLCs), only three out of seven (i.e. SLC10A1, SLC10A2, and SLC10A6) show sodium-dependent uptake of organic substrates across the cell membrane. These include the uptake ...
Flower Darren R - - 2012
In this work we propose the hypothesis that replacing the current system of representing the chemical entities known as amino acids using Latin letters with one of several possible alternative symbolic representations will bring significant benefits to the human construction, modification, and analysis of multiple protein sequence alignments. We propose ...
Barrowman Jemima - - 2012
The proteolytic maturation of the nuclear protein lamin A by the zinc metalloprotease ZMPSTE24 is critical for human health. The lamin A precursor, prelamin A, undergoes a multi-step maturation process that includes CAAX processing (farnesylation, proteolysis and carboxylmethylation of the C-terminal CAAX motif), followed by ZMPSTE24-mediated cleavage of the last ...
Sykaras Alexandros G - - 2012
Enteroendocrine cells have a critical role in regulation of appetite and energy balance. I-cells are a subtype of enteroendocrine cells localized in duodenum that release cholecystokinin in response to ingested fat and amino-acids. Despite their potentially pivotal role in nutrient sensing and feeding behaviour, native I-cells have previously been difficult ...
Wu Tianfu - - 2012
The metabolic disturbances that underlie systemic lupus erythematosus are currently unknown. A metabolomic study was executed, comparing the sera of 20 SLE patients against that of healthy controls, using LC/MS and GC/MS platforms. Validation of key differences was performed using an independent cohort of 38 SLE patients and orthogonal assays. ...
Lei Jian - - 2012
Optimal growth and health of suckling neonates critically depend on milk production by their mothers. In both humans and animals, branched-chain amino acids (BCAA) are not only the major components of milk proteins but are also nitrogenous precursors for the synthesis of glutamate, glutamine, alanine, and aspartate in the mammary ...
Marschall Hanns-Ulrich HU Department of Internal Medicine, The Sahlgrenska Academy, Institute of Medicine, Gothenburg, Sweden. - - 2012
Rifampicin (RIFA) and ursodeoxycholic acid (UDCA) were found to stimulate different but complementary hepatobiliary detoxification pathways in gallstone patients. To study whether single drug effects are sustained or even enhanced by combination of both drugs and whether possible effects are mediated by circulating fibroblast growth factor 19 (FGF19), which has ...
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