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Tantry Subramanyam J - - 2007
An epimerization free and efficient total synthesis of immunosuppressant cyclosporin O (CsO) by step-by-step assembly of amino acids in solution phase is reported. The couplings were performed by employing Fmoc-amino acid chlorides and were mediated by zinc dust under neutral conditions. The yield and purity of the coupling of sterically ...
Bailly Marc - - 2007
Asparagine, one of the 22 genetically encoded amino acids, can be synthesized by a tRNA-dependent mechanism. So far, this type of pathway was believed to proceed via two independent steps. A nondiscriminating aspartyl-tRNA synthetase (ND-DRS) first generates a mischarged aspartyl-tRNAAsn that dissociates from the enzyme and binds to a tRNA-dependent ...
Doi Yoshio - - 2007
Nonnatural amino acids have been introduced into proteins using expanded protein biosynthesis systems. However, some nonnatural amino acids, especially those containing large aromatic groups, are not efficiently incorporated into proteins. Reduced binding efficiency of aminoacylated tRNAs to elongation factor Tu (EF-Tu) is likely to limit incorporation of large amino acids. ...
Demeure Kevin - - 2007
In-source decay (ISD) in MALDI leads to c- and z-fragment ion series enhanced by hydrogen radical donors and is a useful method for sequencing purified peptides and proteins. Until now, most efforts to improve methods using ISD concerned instrumental optimization. The most widely used ISD matrix is 2,5-dihydroxybenzoic acid (DHB). ...
Stoltzfus Arlin - - 2007
Since the genetic code first was determined, many have claimed that it is organized adaptively, so as to assign similar codons to similar amino acids. This claim has proved difficult to establish due to the absence of relevant comparative data on alternative primordial codes and of objective measures of amino ...
Dalal Seema - - 2007
During the erythrocytic stage of its life cycle, the human malaria parasite Plasmodium falciparum catabolizes large quantities of host-cell hemoglobin in an acidic organelle, the food vacuole. A current model for the catabolism of globin-derived oligopeptides invokes peptide transport out of the food vacuole followed by hydrolysis to amino acids ...
Karkhanis Vrajesh A - - 2007
Leucyl-tRNA synthetase (LeuRS) has evolved an editing function to clear misactivated amino acids. An Escherichia coli-based assay was established to identify amino acids that compromise the fidelity of LeuRS and translation. Multiple nonstandard as well as standard amino acids were toxic to the cell when LeuRS editing was inactivated.
Ohuchi Masaki M Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, - - 2007
Flexizymes are de novo ribozymes capable of charging a wide variety of non-natural amino acids on tRNAs. The flexizyme system enables reprogramming of the genetic code by reassigning the codons that are generally assigned to natural amino acids to non-natural residues, and thus mRNA-directed synthesis of non-natural polypeptides can be ...
Xu Libo - - 2007
Thiazolyl peptide antibiotic nocathiacin I (1) was converted to nocathiacin acid (4) in high yield by treatment with trifluoroacetic anhydride and pyridine in THF at room temperature. Two equipotent water-soluble amide analogues of nocathiacin I were readily prepared from this important and versatile carboxylic acid intermediate under mild peptide coupling ...
Tlusty Tsvi - - 2007
The genetic code maps the 64 nucleotide triplets (codons) to 20 amino acids. Some argue that the specific form of the code with its 20 amino acids might be a 'frozen accident' because of the overwhelming effects of any further change. Others see it as a consequence of primordial biochemical ...
Igarashi Naoko - - 2007
Tryptophan (Trp), an aromatic amino acid, is a constituent of peptides/proteins and is also a precursor of serotonin, kynurenine derivatives, and nicotinamide adenine dinucleotides. There have been a number of reports on photochemical reactions involving peptides/proteins which contain Trp that showed significant photodegradation, dimerization, and photoionization. The photochemical properties of ...
Gredicak M - - 2008
Three groups of chloroenyne-modified amino acids were synthesized. Chloroenyne moiety was attached at the N- or C-terminal amino acid (Tyr, Phe, Val, Gly, Lys) position carrying different protecting groups. Prepared derivatives will be used as building blocks in the synthesis of enediyne-peptide conjugates. Furthermore, reactivity of modified amino acids in ...
Wong Jeffrey Tze-Fei - - 2007
The coevolution theory proposes that primordial proteins consisted only of those amino acids readily obtainable from the prebiotic environment, representing about half the twenty encoded amino acids of today, and the missing amino acids entered the system as the code expanded along with pathways of amino acid biosynthesis. The isolation ...
Root-Bernstein Robert - - 2007
The origin of homochirality in molecules characterizing living systems has remained a mystery since Pasteur's recognition of the problem some 150 years ago.(2-5) Most theories also assume that homochirality emerged in one class of molecules (e.g. ribose) from which it was enriched in other molecules (e.g. amino acids) as well.(2-5)I ...
Kopec Susanne - - 2007
Quality control of active pharmaceutical ingredients (API) is commonly performed by means of HPLC. However, CE offers a suitable alternative, especially for the analysis of easily chargeable substances, i.e., amino acids. The article reviews, on the one hand, CE methods developed for impurity profiling of synthesized amino acid analogs. However, ...
Wallner Fredrik K - - 2007
Gel-phase (19)F NMR spectroscopy is a useful monitoring technique for solid-phase organic chemistry due to the high information content it delivers and swift acquisition times, using standard NMR spectrometers. This paper describes the synthesis of the novel linker 2-(2-fluoro-4-hydroxymethyl-5-methoxy-phenoxy)acetic acid in 29% yield over seven steps, using nucleophilic aromatic substitutions ...
Katritzky Alan R - - 2007
Hindered amino acids have been introduced into peptide chains by coupling N-(Cbz- and Fmoc-alpha-aminoacyl)benzotriazoles with amino acids, wherein at least one of the components was sterically hindered, to provide compounds 3a-e, (3c +3 c'), 5a-d, (5a + 5a'), 6a-c, (6b + 6b'), 8a-c, 9a-e, 10a-d, and (10a + 10a') in ...
Benetoli Luís O B - - 2007
In the present paper, the adsorption of amino acids (Ala, Met, Gln, Cys, Asp, Lys, His) on clays (bentonite, kaolinite) was studied at different pH (3.00, 6.00, 8.00). The amino acids were dissolved in seawater, which contains the major elements. There were two main findings in this study. First, amino ...
Hornbogen Till - - 2007
A 51 kDa fusion protein incorporating the N-methyltransferase domain of the multienzyme enniatin synthetase from Fusarium scirpi was expressed in Saccharomyces cerevisiae. The protein was purified and found to bind S-adenosyl methionine (AdoMet) as demonstrated by cross-linking experiments with (14)C-methyl-AdoMet under UV irradiation. Cofactor binding at equilibrium conditions was followed ...
Biegel Annegret - - 2007
The H(+)/peptide cotransporters PEPT1 and PEPT2 have gained considerable interest in pharmaceutical sciences as routes for drug delivery. It is, therefore, of interest to develop uncommon artificial substrates for the two carriers. This study was initiated to investigate the binding affinity of 2-aminothiazole-4-acetic acid (ATAA) conjugates with amino acids to ...
Strieter Eric R - - 2007
During the biosynthesis of the cyclopropyl amino acid coronamic acid from l-allo-Ile by the phytotoxic Pseudomonas syringae, the aminoacyl group covalently attached to the pantetheinyl arm of CmaA is shuttled to the HS-pantetheinyl arm of the protein CmaD by the aminoacyltransferase CmaE. CmaE will only recognize deacylated CmaA for initial ...
Shetty Vivekananda V Skirball Institute of Biomolecular Medicine and Department of Pharmacology, New York University School of Medicine, New York, New York 10016, - - 2007
Cysteine sulfenic acid (Cys-SOH) is an elusive intermediate in reactive oxygen species-induced oxidation reactions of many proteins such as peroxiredoxins and tyrosine phosphatases. Cys-SOH is proposed to play a vital role in catalytic and signaling functions. The formation of cysteine sulfinic acid (Cys-SO(2)H) and cysteine sulfonic acid (Cys-SO(3)H) has been ...
Whitney Michael L - - 2007
Cytoplasmic tRNAs have recently been found to accumulate in the nucleus during amino acid starvation in yeast. The mechanism and regulation by which tRNAs return to the nucleus are unclear. Here, we show accumulation of cytoplasmic tRNA in the nucleus also occurs during glucose starvation. Nuclear accumulation of tRNA in ...
Sladojevich Filippo - - 2007
Enantiopure Fmoc-protected morpholine-3-carboxylic acid was synthesized from dimethoxyacetaldehyde and serine methyl ester through a short and practical synthetic route. The preparation consisted of a five-step process based on reductive amination, intramolecular acetalization, and concomitant elimination of the anomeric methoxy substituent, followed by hydrogenation of the double bond and final acidic ...
Pritz Stephan - - 2007
Sortase A is a transpeptidase that cleaves at a pentapeptide-motif and subsequently transfers the acyl component to a nucleophile containing N-terminal oligoglycines. We investigate the reaction conditions of the sortase-mediated ligation and demonstrate a useful application by the synthesis of a peptide nucleic acid-cell-penetrating peptide chimera, the reaction equilibrium of ...
Cheison Seronei Chelulei - - 2007
An initial 5% (w/v), followed thereafter with replacement aliquots of 3% (w/v), whey protein isolate (WPI) (ca. 86.98% Kjeldahl N x 6.38), was hydrolyzed using Protease N Amano G (IUB 3.4.24.28, Bacillus subtilis) in an enzymatic membrane reactor (EMR) fitted with either a 10 or 3 kDa nominal molecular weight ...
Duca Maria - - 2007
Described herein is the preparation of new bisacylated tRNAs and their participation in protein synthesis. It has been reported that Thermus thermophilus phenylalanyl-tRNA synthetase can introduce two phenylalanine moieties onto the 3'-terminal adenosine of its cognate tRNA. It is also possible to prepare bisactivated tRNAs in vitro; these participate in ...
Isidro-Llobet Albert - - 2007
[reaction: see text] p-Nitromandelic acid as a safety-catch linker for Boc/Bzl-SPPS of base-labile compounds like peptides and depsipeptides is described. This linker permits acidic removal of side-chain protection groups from the resin. For cleavage from the solid support, the p-nitro group was reduced with tin(II) chloride. After washing off the ...
Sarvestani Alireza S - - 2007
Hydrogel/apatite nanocomposites are the ideal biomaterial to mimic the physio-chemical and biologic properties of the bone and to fabricate scaffolds for bone regeneration. The objective of this work was to investigate the effect of an osteonectin derived glutamic acid sequence on the viscoelastic properties of poly(lactide-ethylene oxide-fumarate) (PLEOF)/apatite composite, as ...
Hosotani Nobuo - - 2007
A new peptaibol compound, SPF-5506-A4, was isolated from the fermentation broth of Trichoderma sp. SPF-5506. The chemical structure of the 14-residue peptide was determined by MS, NMR and amino acid sequence analyses. The absolute configuration of amino acid residues in the acid hydrolysate was determined by Marfey's method. The structure ...
Palasek Stacey A - - 2007
Microwave energy represents an efficient manner to accelerate both the deprotection and coupling reactions in 9-fluorenylmethyloxycarbonyl (Fmoc) solid phase peptide synthesis (SPPS). Typical SPPS side reactions including racemization and aspartimide formation can occur with microwave energy but can easily be controlled by routine use of optimized methods. Cysteine, histidine, and ...
Zhai Yuxin - - 2007
The aminoacyl-tRNA synthetases covalently link transfer RNAs to their cognate amino acids. Some of the tRNA synthetases have evolved editing mechanisms to ensure fidelity in this first step of protein synthesis. The amino acid editing site for leucyl- (LeuRS) and isoleucyl- (IleRS) tRNA synthetases reside within homologous CP1 domains. In ...
Yagi Nobuhiro - - 2007
A novel lipid analog based on amino acids for liposome modification was developed. It consisted of three different kinds of amino acid derivatives and two fatty acids, and can react directly with the peptide synthesized first on resin by Fmoc solid-phase synthesis. In this study, lipid analog conjugated with HIV-TAT ...
Germann Markus W MW Department of Chemistry, Georgia State University, P.O. Box 4098, Atlanta, Georgia 30302-4098, - - 2007
In this work, the translational self-diffusion constants, DT's, of 12 amino acids (Ala, Arg, Asn, Asp, Cys, Glu, His, Ile, Lys, Met, Phe, and Ser) are measured by field gradient NMR and extrapolated to infinite dilution. The experiments were carried out in D2O at 298 K at pD approximately =3.5 ...
Silvester Nicole C - - 2007
The effect of various charged or hydrophobic amino acids on the hybridisation of fully complementary and mismatch PNA-DNA duplexes was investigated via UV melting curve analysis. The results described here show that the thermal stability and binding specificity of PNA probes can be modified by conjugation to amino acids and ...
Abes S S Université Montpellier 2, UMR 5124 CNRS, place Eugene Bataillon, 34095 Montpellier cedex 5, - - 2007
CPPs (cell-penetrating peptides) have given rise to much interest for the delivery of biomolecules such as peptides, proteins or ONs (oligonucleotides). CPPs and their conjugates were initially thought to translocate through the cell membrane by a non-endocytotic mechanism which has recently been re-evaluated. Basic-amino-acid-rich CPPs first interact with cell-surface proteoglycans ...
Forbes Chris D - - 2007
An enhanced method to measure the concentration of individual naturally occurring free amino acids in solution is described. This relatively simple but robust method combines two previously reported procedures: the use of scintillation proximity assay (SPA) technology to measure aminoacyl-tRNA synthetase (aaRS) activity and the use of aaRS activity to ...
Jiang Zhong-Xing ZX Department of Pharmaceutics and Pharmaceutical Chemistry, College of Pharmacy, University of Utah, Salt Lake City, Utah 84112, - - 2007
To modulate and report the pharmacokinetics of peptide-based pharmaceuticals, a novel geminally perfluoro-tert-butylated beta-amino acid (betaFa) and its Fmoc- and Boc-protected forms were designed and synthesized. betaFa was incorporated into a model tripeptide via standard solid-phase chemistry. Both the amino acid (free and protected) and the tripeptide show a sharp ...
Attard Troy J - - 2007
The 2-(p-biphenylyl)-2-propyloxycarbonyl (Bpoc) group was examined as an N(alpha)-protecting group in the stepwise assembly of the MAP Kinase ERK2 [178-188; Thr(P)(183), Tyr(P)(185)] peptide. The mild acid deprotection of the Bpoc group permitted (i) incorporation of a fully protected phosphothreonyl derivative and (ii) a TFA-based final cleavage step. The first five ...
Knight Martha - - 2007
Synthetic peptides with many aromatic, aliphatic and especially acidic amino acid residues are not very soluble and require strong solvents for useful partitioning. A chloroform-methanol-acidic solvent system fractionates neutral and basically charged 26-mers to provide high yields. An insoluble 15-mer with 5 Trp residues and 60% overall hydrophobic amino acid ...
Fujita Masashi - - 2007
BACKGROUND: Selenocysteine and pyrrolysine are the 21st and 22nd amino acids, which are genetically encoded by stop codons. Since a number of microbial genomes have been completely sequenced to date, it is tempting to ask whether the 23rd amino acid is left undiscovered in these genomes. Recently, a computational study ...
Tilvi Supriya - - 2007
Spectra obtained using electrospray ionization mass spectrometry (ESI-MS) of the mollusk Elysia grandifolia showed a cluster of molecular ion peaks centered at a molecular mass of 1478 Da (kahalalide F, an anticancer agent). Two new molecules, kahalalide R (m/z 1464) and S (m/z 1492) were characterized using tandem mass spectrometry. ...
Sandbrink Jessica - - 2007
A solid phase synthesis strategy for post-conjugation of amino acids and a phenanthroline derivative to peptide nucleic acids is described. The peptide nucleic acids, synthesized by 9-fluorenylmethyloxycarbonyl chemistry on TentaGel S Rink Amide resin, have an internally placed unit carrying an amino linker with 4-methyltrityl protection. Methyltrityl removal by mild ...
Kawakami Takashi - - 2007
Here we describe the ribosomal synthesis of peptides containing an N(alpha)-methylated amino acid by using sense-suppression method. To incorporate the various N(alpha)-methylated amino acids into the peptide, we utilized recently developed two technologies, a ribozyme-based tRNA acylation system (Flexizyme system) and a reconstituted cell-free translation system (PURE system). Firstly, various ...
Ambrogelly Alexandre - - 2007
At the time of its discovery four decades ago, the genetic code was viewed as the result of a "frozen accident." Our current knowledge of the translation process and of the detailed structure of its components highlights the roles of RNA structure (in mRNA and tRNA), RNA modification (in tRNA), ...
Miklán Zsanett - - 2007
Data reported in this article describe the synthesis of Arg-rich oligopeptide conjugates of ferrocenecarboxylic acid on solid support with two different strategies and for the first time, the successful preparation of peptide conjugates of ferrocenylacrylic acid in solution. The antitumor effect of conjugates was analyzed by MTT assay in vitro. ...
Zhang Jian - - 2007
The effects of neighboring residues and formulation variables on tyrosine oxidation were investigated in model dipeptides (glysyl tyrosine, N-acetyl tyrosine, glutamyl tyrosine, and tyrosyl arginine) and tripeptide (lysyl tyrosyl lysine). The tyrosyl peptides were oxidized by light under alkaline conditions by a zero-order reaction. The rate of the photoreaction was ...
SzymaƄski Maciej - - 2007
The genetic code discovered 40 years ago, consists of 64 triplets (codons) of nucleotides. The genetic code is almost universal. The same codons are assigned to the same amino acids and to the same START and STOP signals in the vast majority of genes in animals, plants, and microorganisms. Each ...
Liu Xiangyang - - 2007
Lipopeptides are amphiphilic compounds which contain both hydrophobic fatty acid moieties and amphiphilic peptide moieties. From the cell-free broth of Bacillus subtilis HSO121, eight cyclic lipopeptides were isolated by reversed-phase high performance liquid chromatography (RP-HPLC). The peptide part of each lipopeptide was elucidated according to electrospray ionization quadruple-time-of-flight mass spectrometry ...
Herring Stephanie - - 2007
Pyrrolysine (Pyl), the 22nd co-translationally inserted amino acid, is incorporated in response to a UAG amber stop codon. Pyrrolysyl-tRNA synthetase (PylRS) attaches Pyl to its cognate tRNA, the special amber suppressor tRNA(Pyl). The genes for tRNA(Pyl) (pylT) and PylRS (pylS) are found in all members of the archaeal family Methanosarcinaceae, ...
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