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Results 201 - 250 of 1403
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Azim M Kamran - - 2008
Non-canonical amino acids (NAA), as building blocks for peptides and proteins during ribosomal translation, represent a nearly infinite supply of novel functions. The specific selection, activation and tRNA-charging of amino acids by aminoacyl-tRNA synthetases (AARS) in the aminoacylation reaction are essential steps. In most cases, aminoacylation of N(AA) is a ...
Kino Kuniki - - 2008
l-Amino acid alpha-ligase (EC 6.3.2.28) catalyzed formation of alpha-peptide bond in unprotected l-amino acids in an ATP-dependent manner. BL00235 gene in Bacillus licheniformis NBRC12200 coded as a new l-amino acid ligase. BL00235 substrate specificity was strict; only methionine or leucine was acceptable as dipeptide N-terminal residues.
Zeng Yan - - 2008
Compound 1 as an electron donor-acceptor compound with N,N-dimethylaniline and quinone units was designed for a highly selective colorimetric determination of thiol-containing amino acids and peptides, by making use of the unique reactivity of thiol towards quinone. Compound 1 shows a strong intramolecular charge transfer (ICT) band around 582nm; but, ...
Chen Shengxi - - 2008
Described herein is the preparation of new aminoacylated derivatives of the dinucleotide pdCpA, and of transfer RNAs. The focus of the present work is the synthesis of amino acid analogs related to aspartic acid and cysteine species that have important functional roles in many proteins. The activated aminoacyl-tRNAs prepared can ...
Isidro-Llobet Albert - - 2008
The 5-(4-hydroxyphenyl)-3,4-ethylenedioxythienyl alcohol (THAL, Thiophene Acid Labile) is described as a new linker for the solid-phase synthesis of peptide carboxylic acids. It is based on the electron-rich 3,4-ethylenedioxythenyl (EDOTn) moiety and allows the obtention of free and tert-butyl-protected peptides by cleavage with 90% and 0.5% TFA, respectively. This very high ...
Morgan Philip E - - 2008
Hydroperoxides are major reaction products of radicals and singlet oxygen with amino acids, peptides, and proteins. However, there are few data on the distribution of hydroperoxides in biological samples and their sites of formation on peptides and proteins. In this study we show that normal-or reversed-phase gradient HPLC can be ...
Di Giacco Viviana - - 2008
During translation, usually only one in approximately 400 misincorporations affects the function of a nascent protein, because only chemically similar near-cognate amino acids are misincorporated in place of the cognate one. The deleterious misincorporation of a chemically dissimilar noncognate amino acid during the selection process is precluded by the presence ...
Liu Xiang-Yang - - 2008
A new lipopeptide with C12 fatty acid has been isolated from the cell broth of Bacillus subtilis HSO121 by chromatographic methods, which is believed to be the homologue of lipopeptides. The fatty acid portion was methylated and analyzed by GC/MS, ESI Q-TOF MS and 1H-NMR. The peptide portion, of which ...
Cargile Benjamin J - - 2008
Current algorithms for the calculation of peptide or protein pI, based on the charge associated with individual amino acids, can calculate pI values to within +/-0.2 pI units. Here, we present a new pI calculation algorithm that takes into account the effect of adjacent amino acids on the pI value. ...
Kaufmann Doris - - 2008
An elastin-mimetic polypeptide, (EMM)(7), with the amino-acid sequence GRDPSS [VPGVG VPGKG VPGVG VPGVG VPGEG VPGIG](7) was used for chemical conjugation of various integrin ligands (RGD peptides) to prepare bioactive hydrogels. The chemical approach involved (1) chemical protection of lysine residues with Fmoc or Boc groups, (2) chemical ligation of a ...
Deaudelin Philippe - - 2008
Sixteen pyrrolo[3,2- e][1,4]diazepin-2-ones 1 were synthesized in 4-5 steps and 5-48% overall yields from 4-oxoproline 8 by a route featuring a diastereoselective Pictet-Spengler reaction to close the seven-membered diazepinone ring. Crystallographic analysis of pyrrolo[3,2- e][1,4]diazepin-2-one 1b by X-ray diffraction demonstrated that the alpha-amino acid residue adopted dihedral angle geometry similar ...
Melquiond Adrien - - 2008
Self-assembly of the 40/42 amino acid Abeta peptide is a key player in Alzheimer's disease. Abeta40 is the most prevalent species, while Abeta42 is the most toxic. It has been suggested that the amino acids 21-30 could nucleate the folding of Abeta monomer and a bent in this region could ...
Ito Hisashi - - 2008
1,2-Epoxy-3-(p-nitrophenoxy)propane (EPNP) is known to inhibit pepsin A and other aspartic proteinases by reacting with the active site aspartic acid residue(s). However, the reaction is considerably slow in general, and therefore, it is desirable to develop similar reagents that are capable of inhibiting these enzymes more rapidly. In the present ...
Denekamp Chagit - - 2008
Primary and secondary alkyl amines substitute readily one of the para-methoxy substituents of tris(2,4,6-trimethoxyphenyl)methyl carbenium ion. With this rapid process, the preparation of permanently charged positive derivatives of amines, amino acids and small C-protected peptides is achieved. This is utilized here to facilitate the matrix assisted laser desorption ionization-time-of-flight (MALDI-TOF) ...
Lang Alexander - - 2009
The enzymatic synthesis of N-protected L-aminoacyl- and L-peptidyl-antipyrine amides was accomplished by proteases from different classes. Serine and cysteine proteases proved to be suitable tools for the production of amino acids and peptides conjugated to 4-aminoantipyrine, whereas metalloproteases do not seem to be very qualified for accepting this nucleophile. The ...
Simó Carolina C Department of Chemistry, Materials and Chemical Engineering Giulio Natta, Polytechnic of Milano, 20131 Milano, - - 2008
For a better understanding of the behavior of solid-phase combinatorial peptide ligands for capturing the red blood cell low-abundance soluble proteome, combinatorial peptides of different lengths from a single amino acid up to a hexapeptide were evaluated. A red blood cell lysate (6 g total protein) was loaded in a ...
Gruffat D - - 2008
Although endogenous synthesis of conjugated linoleic acid (CLA) in the mammary gland of lactating cows has been already well documented, no study has determined so far as to which tissue and/or organ is involved in CLA synthesis in the growing ruminant except one study showing that CLA synthesis does not ...
Hojo Hironobu - - 2008
Aryl thioesters of peptide segments were prepared by the conventional 9-fluorenylmethoxycarbonyl (Fmoc) strategy using a novel N-alkyl cysteine (NAC)-assisted thioesterification reaction. The peptide carrying NAC at its C-terminus was prepared by the Fmoc strategy and converted to the aryl thioester by 4-mercaptophenylacetic acid (MPAA) treatment without significant side reactions. The ...
Kugimiya Akimitsu - - 2008
The detection of amino acids using aminoacyl-tRNA synthetases (ARSs) as the molecular recognition element was proposed, and the binding activity and specificity of ARSs were evaluated. Using this rapid and easy method, from 15 to 50 microM tyrosine could be measured specifically. The method suggested in this article could be ...
Venkata Ramana A - - 2008
N-Substituted cyclam-amino acid conjugates have been synthesised both in solution and on the solid phase. The DNA binding affinity of these species has been studied: the nature of the amino acid strongly influences the change in melting temperature suggesting that simple cyclam-peptide conjugates could interact with DNA in a highly ...
Ewing Michael A - - 2008
Neuropeptides, gene products that undergo extensive post-translational modification (PTM), are frequently characterized using mass spectrometry (MS). One PTM in particular, the conversion of an L-amino acid to a D-amino acid, has no associated mass shift. Therefore, this PTM is difficult to evaluate using MS alone, especially in complex peptide mixtures. ...
Ruczyński Jarosław - - 2008
The sequence-dependent, acid- or base-catalysed aspartimide formation is one of the most serious side reactions in solid-phase synthesis of peptides containing aspartic acid. In the present work, we investigated the susceptibility of 4-(N-[1-(4,4-dimethyl-2,6-dioxocyclohexylidene)-3-methylbutyl]amino)benzyl (Dmab), an aspartic acid beta-carboxy side-chain protecting group, for aspartimide formation. As a model, 15-amino acid-residue galanin ...
Tomsho John W - - 2008
Protein translation in nature always begins with an initiator transfer RNA (tRNA) carrying the amino acid methionine. This was circumvented in vitro with a reconstituted translation system utilizing initiator tRNA synthetically mischarged with the other natural amino acids. In addition, it was determined that this system could accommodate these non-methionine ...
Ledoux Sarah - - 2008
The analysis of reactions involving amino acids esterified to tRNAs traditionally uses radiolabeled amino acids. We describe here an alternative assay involving [3'-32P]-labeled tRNA followed by nuclease digestion and TLC analysis that permits aminoacylation to be monitored in an efficient, quantitative manner while circumventing many of the problems faced when ...
Duca Maria - - 2008
The detailed synthesis of (bis)aminoacyl-pdCpAs and the corresponding singly and tandemly activated tRNAs is reported. The synthetic pathway leading to these compounds has been validated for simple amino acid residues as well as for amino acids bearing more complex side chains. Protection/deprotection strategies are described. For the bisaminoacylated tRNAs, both ...
Sheppard Kelly K Department of Molecular Biophysics and Biochemistry, Yale University, 266 Whitney Avenue, New Haven, CT 06520-8114, - - 2008
Selenocysteinyl-tRNA(Sec), cysteinyl-tRNA(Cys), glutaminyl-tRNA(Gln), and asparaginyl-tRNA(Asn) in many organisms are formed in an indirect pathway in which a non-cognate amino acid is first attached to the tRNA. This non-cognate amino acid is then converted to the cognate amino acid by a tRNA-dependent modifying enzyme. The in vitro characterization of these modifying ...
Splan Kathryn E KE Department of Chemistry, Macalester College, St. Paul, MN 55105, - - 2008
Aminoacyl-tRNA synthetases are essential enzymes that help to ensure the fidelity of protein translation by accurately aminoacylating (or "charging") specific tRNA substrates with cognate amino acids. Many synthetases have an additional catalytic activity to confer amino acid editing or proofreading. This activity relieves ambiguities during translation of the genetic code ...
Polavarapu Lakshminarayana - - 2008
We demonstrated a simple single-step synthesis of gold nanochains by reducing aqueous chloroaurate ions (AuCl(4)(-)) with sodiumborohydride (NaBH(4)) in the presence of an amino acid (glutamic acid and histidine) as a stabilizer. The structure and optical properties of gold nanochains and nanowires were characterized by transmission electron microscopy, UV-visible spectroscopy, ...
Broyer Rebecca M - - 2008
A synthetic strategy to prepare peptide-polymer conjugates with precise sites of attachment is described. Amino acids modified with atom transfer radical polymerization (ATRP) initiators for the polymerization of styrenes and methacrylates were prepared. Fmoc-4-(1-chloroethyl)-phenylalanine (5) was synthesized in four steps from Fmoc-tyrosine. HATU-mediated amidation with glycine-OMe resulted in dipeptide (6). ...
Lesner Adam - - 2008
In the current work, a synthesis of new sensitive fluorescence substrates of cathepsin G is reported. The substrate sequence was selected using combinatorial chemistry methods. The starting structure of chromogenic cathepsin G substrate Ac-Phe-Val-Thr-Gnf-ANB-NH(2), where Gnf stands for 4-guanidine-l-phenylalanine, was modified by replacing the acetyl moiety with a residue of ...
Swatkoski Stephen - - 2008
Microwave-accelerated proteolysis using acetic acid has been shown to occur specifically on either or both sides of aspartic acid residues. This chemical cleavage has been applied to ovalbumin and several model peptides to test the effect on some of the more common post-translational modifications. No oxidation of methionine or cysteine ...
Tamura Koji - - 2008
The origin of homochirality of l-amino acids has long been a mystery. Aminoacylation of tRNA might have provided chiral selectivity, since it is the first process encountered by amino acids and RNA. An RNA minihelix (progenitor of the modern tRNA) was aminoacylated by an aminoacyl phosphate oligonucleotide that exhibited a ...
Koda Yasuko - - 2008
We have previously shown that the stability and permeability of peptides can be greatly improved by conjugation with lipoamino acids such as 2-aminododecanoic acid (C12Laa). However, the increase in lipophilicity which this conjugation provides can also cause a significant decrease in the compound's water solubility. In this study, we coupled ...
Diss Maria L - - 2008
We describe the design and exploration of new buried polar groups to control coiled-coil dimerization. Employing our recently described method for on-resin guanidinylation, we have prepared coiled-coil peptides with a single core guanidine, spaced from the backbone by 1-3 methylene groups. Heterodimeric mixtures of these sequences with guanidine, amide, and ...
Tamura Koji - - 2008
The aminoacylation of tRNA, a process in which amino acids first encounter RNA, may be closely related to the origin of L-amino acid homochirality in biological systems. A clear preference for L-amino acids as opposed to D-amino acids was noted in the efficient nonenzymatic aminoacylation of an RNA minihelix (progenitor ...
Bergeon Julie A - - 2008
In recent years, the conjugation of sugar moieties and lipoamino acids has been extensively investigated as a mean to enhance the stability towards enzymatic degradation and the permeability across biological membranes of poorly orally available drugs, including peptides. In this prospect, a library of novel derivatives of the dipeptide L-Glu-L-Trp, ...
Klisch Manfred - - 2008
Marine microorganisms harbor a multitude of secondary metabolites. Among these are toxins of different chemical classes as well as the UV-protective mycosporine-like amino acids (MAAs). The latter form a group of water-soluble, low molecular-weight (generally < 400) compounds composed of either an aminocyclohexenone or an aminocyclohexenimine ring, carrying amino acid ...
Audsley Neil - - 2008
The transepithelial flux of cydiastatin 4 and analogs across flat sheet preparations of the anterior midgut of larvae of the tobacco hawkmoth moth, Manduca sexta, was investigated using a combination of reversed-phase high-performance liquid chromatography (RP-HPLC), enzyme-linked immunosorbent assay (ELISA) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF ...
Ressurreição Ana Sofia M - - 2008
A practical synthesis of a new bifunctional diketopiperazine (DKP) scaffold 1, formally derived from the cyclization of L-aspartic acid and (S)-2,3-diaminopropionic acid, is reported. DKP-1 bears a carboxylic acid and an amino functionalities in a cis relationship, which have been used to grow peptide sequences. Tetra-, penta-, and hexapeptidomimetic sequences ...
Nahas Deborah D - - 2008
Amino acid analysis using direct electrochemical detection was compared with precolumn fluorescent derivatization using 6-aminoquinolyl- N-hydroxysuccinimidyl carbamate (AQC) for evaluation of the degree of covalent coupling of peptides to a carrier-protein complex derived from the bacteria Neisseria meningitidis. AQC derivatization was found to give superior sensitivity compared to electrochemical detection, ...
Owczarek Alina - - 2008
Incorporation of unnatural amino acids with unique chemical functionalities has proven to be a valuable tool for expansion of the functional repertoire and properties of proteins as well as for structure-function analysis. Incorporation of alpha-hydroxy acids (primary amino group is substituted with hydroxyl) leads to the synthesis of proteins with ...
Tian Zhixin - - 2008
Hydrogen-deuterium exchange reactions of deprotonated amino acids and small peptides were studied. Selective labeling can be carried out at the alpha-amino group of lysine (2 of 4 labile hydrogens undergo exchange with CF3CH2OD) and the guanidine side chain of arginine (3 of 6 labile hydrogens undergo exchange with CH3CH2OD and ...
Wainaina Moses N - - 2008
A modified Edman degradation method where fluorescent derivatives of amino acids were generated from the postcleavage products of a peptide is described. In the method, the target peptide was applied onto double glass fiber membranes in a small filter disk (4 mm i.d.) and then treated with small amounts of ...
Grage Stephan L - - 2008
A representative set of amino acids with aliphatic 19F-labels has been characterized here, following up our previous compilation of NMR parameters for single 19F-substituents on aromatic side chains. Their isotropic chemical shifts, chemical shift tensor parameters, intra-molecular 19F dipole-dipole couplings and temperature-dependent T1 and T2 relaxation times were determined by ...
Schulze Heike - - 2007
Human acid ceramidase catalyzes the last step of lysosomal sphingolipid degradation, the hydrolysis of ceramide to sphingosine and free fatty acid. Inherited deficiency of acid ceramidase activity leads to Farber disease (Farber lipogranulomatosis). In this study, we describe the overexpression and processing of recombinant human acid ceramidase in Sf21 insect ...
Fournier Frédéric - - 2008
We employ a particular form of two-dimensional infrared four-wave mixing (2DIR FWM) as a vibrational spectroscopic tool to quantify the amino acid content of a number of peptides. Vibrational features corresponding to ring modes of the aromatic groups of phenylalanine (Phe) and tyrosine (Tyr), as well as a methylene mode ...
Marsh Derek - - 2008
TOAC (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid) is a nitroxyl amino acid that can be incorporated in the backbone of peptides. DOXYL (4,4-dimethyl-oxazolidine-1-oxyl) is a nitroxyl ring that can be attached rigidly at specific C-atom positions in the acyl chains of phospholipids. Spin-labelled phosphatidylcholines of the DOXYL type have been used previously to establish ...
Reinbold Corbett J A CJ Laboratory of Molecular Immunology, Blood Research Institute, Milwaukee, WI 53226, - - 2008
Immune specificity of a T cell is determined by the TCR contact residues exposed on the antigenic peptide/MHC complex. Naturally processed, biallelic epitopes from H7 minor histocompatibility (mH) antigen vary in position 7 (p7) from aspartic acid (D) to a glutamic acid (E), which differ by an additional methylene (-CH(2)) ...
Wu Y - - 2007
Lysozyme [EC 3.2.1.17] was covalently attached to polystyrene resin beads by the sole histidine residue (His-15) through peptide spacers of various lengths. The spacers were amino acid chains composed of 6-aminocaproic acid synthesized with the solid phase peptide synthesis method. Immobilized lysozyme with a spacer length of three 6-aminocaproic acid ...
Wolfe Robert R - - 2007
Transfer RNA (tRNA)-charged amino acids are direct precursors of protein synthesis. Therefore, the amount and profile of amino acids in the aminoacyl-tRNA pool may be closely related to the rate of protein synthesis in the tissue. This study was designed to compare the aminoacyl-tRNA pools in liver and muscle, 2 ...
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