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Results 201 - 250 of 2090
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Crawford Robert W - - 2012
Intestinal inflammation changes the luminal habitat for microbes through mechanisms that have not been fully resolved. We noticed that the FepE regulator of very long O-antigen chain assembly in the enteric pathogen Salmonella enterica serotype Typhimurium (S. Typhimurium) conferred a luminal fitness advantage in the mouse colitis model. However, a ...
Le Devedec Frantz - - 2012
Bile acids are amphiphilic endogenous steroids that act as anionic surfactants in the digestive tract and aggregate in aqueous solutions. Non-ionic surfactants were synthesized by grafting oligo(ethylene glycol) chains of various lengths (pegylation) to three bile acids (lithocholic, deoxycholic, and cholic acid) using anionic polymerization. The aggregation properties of the ...
Toshima Naoko - - 2012
Like mammals, insects need to ingest proteins from foods because they cannot synthesise several amino acids. Amino acids are also essential nutrients for Drosophila melanogaster, especially for female egg production, but how flies detect amino acids and how the feeding response to amino acids is regulated are unknown. In this ...
Pappalardo Andrea - - 2012
A pair of diastereomeric salen cavitands and their uranyl complexes combine a chiral (R,R) salen bridge, and an inherent chiral tris-bridged quinoxaline cup within the same molecule. Whereas the free ligands show a preference for the same enantiomer of an alpha-amino acid pair, the corresponding UO2 complexes display opposite enantiodiscrimination ...
Borkar Prashant - - 2012
Novel synergistic effects between Lewis and Brønsted acids in Prins cyclization are reported. Non-reactive Lewis acids and non-reactive Brønsted acids, which failed to perform Prins cyclization when used alone, have shown remarkable synergistic effects when used in combination to perform the reaction successfully.
Sardella Roccaldo - - 2012
The employment of the flow N-acyl amidation of natural bile acids (BAs) required the in-line connection with suitable analytical tools enabling the determination of reaction yields as well as of the purity grade of the synthesized glyco- and tauro-conjugated derivatives. In this framework, a unique HPLC method was successfully established ...
O'Reilly Elaine - - 2012
Conformationally restricted amino acids are important components in peptidomimetics and drug design. Herein, we describe the synthesis of a novel, non-proteinogenic constrained delta amino acid containing a cyclobutane ring, cis-3(aminomethyl)cyclobutane carboxylic acid (ACCA). The synthesis of the target amino acid was achieved in seven steps, with the key reaction being ...
Fukuhara Gaku - - 2012
A new cyclodextrin-polythiophene conjugate (CDPT) has been prepared by attaching permethyl-α-cyclodextrins to polythiophene (PT) through a hexamethylene tether. Circular dichroism spectral examination of CDPT revealed that only a weak positive Cotton effect (Δε=0.1 M(-1)  cm(-1) ) was induced at the main band of the PT in dimethyl sulfoxide and similarly weak ...
Bai Wen-Ju - - 2012
A general method to construct 3-methyl-4-O-methylated tetramic acids displaying a C-5 stereocenter is presented. The synthetic sequence employs a SmI(2)-mediated cyclization, whereby the chirality of the emerging tetramic acid core is retained from the starting chiral amino acid. Application to palau'imide is discussed.
Ishida Naoki - - 2012
Chiral dehydropiperidinones were synthesized in enantiopure form from α-amino acids and alkynes via azetidin-3-ones.
Ohmori Taketo - - 2012
The effect of alkali treatment on the isomerization of amino acids was investigated. The 100×D/(D+L) values of amino acids from peptide increased with increase in the number of constituent amino acid residues. Furthermore, the N-terminal amino acid of a dipeptide was isomerized to a greater extent than the C-terminal residue.
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 complex three dimensional structures through disulfide bonds or crosslinked amino acids. Peptides are frequently cyclic and contain proteinogenic as well as ...
Podwysocka D - - 2012
β-Amino acids containing α,β-hybrid peptides show great potential as peptidomimetics. In this paper, we describe the synthesis and affinity to μ-opioid and δ-opioid receptors of α,β-hybrids, analogs of the tetrapeptide Tyr- d-Ala-Phe-Phe-NH(2) (TAPP). Each amino acid was replaced with an l- or d-β(3) -h-amino acid. All α,β-hybrids of TAPP analogs ...
Zheng Huajun - - 2012
The amino acid biosynthesis pathway and proteolytic system of Lactobacillus delbrueckii subsp. bulgaricus 2038 (L. bulgaricus 2038), a mainstay of large-scale yogurt production, were modeled based on its genomic sequence. L. bulgaricus 2038 retains more potential for amino acid synthesis and a more powerful proteolytic system than other L. bulgaricus ...
Chen Jianian - - 2012
Dual- and multi-functional drug delivery systems, especially ligand-modified nanoparticles (NPs) loaded with chemotherapeutic agents are paid much attention to due to their excellent behavior in vitro and in vivo. Bifunctional NPs (BF-NPs), which were based on PLGA-PEG and modified with folic acid and cell penetrating peptide R(7) simultaneously, were developed. ...
Robal Terje - - 2012
Angiopoietin-like protein 4 (Angptl4), a potent regulator of plasma triglyceride metabolism, binds to lipoprotein lipase (LPL) through its N-terminal coiled-coil domain (ccd-Angptl4) inducing dissociation of the dimeric enzyme to inactive monomers. In this study, we demonstrate that fatty acids reduce the inactivation of LPL by Angptl4. This was the case ...
Voortman Trudy - - 2012
Gastrointestinal (GI) peptide hormones play an important role in short-term regulation of food intake and blood glucose levels. Modulating their release is of potential relevance for weight management and possibly diabetes. As currently available models are hard to extrapolate to the human situation, we investigated the use of porcine intestinal ...
Boone Tyler J - - 2012
Phosphoglycerate kinase (PGK), present on the surface of group B streptococcus (GBS), has previously been demonstrated to bind the host proteins actin and plasminogen. The actin and plasminogen binding sites of GBS-PGK were identified using truncated GBS-PGK molecules, followed by peptide mapping. These experiments identified two actin and plasminogen binding ...
Calder Philip C - - 2012
Atherosclerosis has an important inflammatory component and acute cardiovascular events can be initiated by inflammatory processes occurring in advanced plaques. Fatty acids influence inflammation through a variety of mechanisms; many of these are mediated by, or associated with, the fatty acid composition of cell membranes. Human inflammatory cells are typically ...
Wernisch Stefanie - - 2012
The intramolecular distances of anion and cation exchanger sites of zwitterionic chiral stationary phases represent potential tuning sites for enantiomer selectivity. In this contribution, we investigate the influence of alkanesulfonic acid chain length and flexibility on enantiomer separations of chiral acids, bases, and amphoteric molecules for six Cinchona alkaloid-based chiral ...
Pitteloud Jean-Philippe - - 2012
A simple and efficient one-pot procedure that enables rapid access to orthogonally protected N,N'-diaminoalkylated basic amino acid building blocks fully compatible with standard Boc and Fmoc solid-phase peptide synthesis is reported. Described synthetic approach includes double reductive alkylation of N (α)-protected diamino acids with N-protected amino aldehydes in the presence ...
Islam Mohammad Monirul - - 2012
Protein solubility is usually characterized in terms of a hydrophobicity scale, which refers to the free energy of transfer of a molecule from an aqueous to a nonpolar solution and is not a "solubility propensity scale" per se. Using a "host-guest" approach, we measured the effects of short poly-amino-acid tags ...
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 ...
Brown Alaina M - - 2012
Type II polyproline helices (PPII) are a fundamental secondary structure of proteins, common in globular and nonglobular regions and important in cellular signaling. We developed a propensity scale for PPII using a host-guest system of sequence Ac-GPPXPPGY-NH2, where X represents any amino acid. We found that proline has the highest ...
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 - - 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 ...
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