- Oligonucleotide promoted peptide bond formation using a tRNA mimicking approach
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TransferRNA's role in protein translation is the prime example of an Informational Leaving Group (ILG). A simplified model produced oligophenylalanine with a modified uracil as an ILG in the presence of specific oligonucleotides. Our preliminary studies contribute to the importance of hybrid species in bridging the gap between peptides and nucleic acids.
- Mattelaer,Mattelaer,Papastavrou,Dehaen,Herdewijn
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supporting information
p. 5013 - 5016
(2017/07/11)
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- Cis-Trans Conformational Analysis of δ-Azaproline in Peptides
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The cis-trans isomerization and conformer specificity of δ-azaproline and its carbamate-protected form in linear and cyclic peptides were investigated using NMR and α-chymotrypsin assay. Comparisons of the chemical shift value of the α-hydrogen in each case of δ-azaproline-containing peptides with conformer-specific locked diketopiperazines reveal the fact that an upfield chemical shift value corresponds to cis conformer and a downfield value corresponds to a trans conformer. δ-Azaproline adopts cis-conformation in simple amides, dipeptides, and tripeptides whereas its carbamate-protected form adopts trans-conformation. In the case of longer, linear or cyclic peptides, vice versa results are obtained. Interestingly, in all these peptides exclusively one conformer, either cis or trans, is stabilized. This cis-trans isomerization is independent of both temperature and solvents; only the δ-nitrogen protecting group plays key role in the isomerization. δ-Azaproline is conformer-specific in either of its protected or deprotected forms, which is a unique property of this proline. Unlike other covalently modified proline surrogates, this isomerization of δ-azaproline can be tuned easily by a protecting group. The mechanism of cis-trans isomerization of δ-azaproline during deprotection and reprotection is supported by theoretical calculations.
- Duttagupta, Indranil,Misra, Debojyoti,Bhunya, Sourav,Paul, Ankan,Sinha, Surajit
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p. 10585 - 10604
(2015/11/18)
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- NOVEL SEMI-SYNTHETIC GLYCOPEPTIDES AS ANTIBACTERIAL AGENTS
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Semi-synthetic glycopeptides having antibacterial activity are described, in particular, the semi-synthetic glycopeptides described herein are made by chemical modification of the a glycopeptide (Compound A, Compound B, Compound H or Compound C) or the monosaccharide made by hydrolyzing the disaccharide moiety of the amino acid-4 of the parent glycopeptide in acidic medium to give the amino acid-4 monosaccharide; conversion of the monosaccharide to the amino-sugar derivative; acylation of the amino substituent on the amino acid-4 amino-substituted sugar moiety on these scaffolds with certain acyl groups; conversion of the amide group in amino acid-3 on these scaffolds to various acylamide, acylsulfonamide, acylsulfonylurea derivatives; aminomethylation with substituent containing sulfonamide or acylsulfonamide group on amino acid-7 through Mannich reaction; and conversion of the acid moiety on the macrocyclic ring of these scaffolds to certain substituted amides. Also provided are methods for the synthesis of the compounds, pharmaceutical compositions containing the compounds, and methods of use of the compounds for the treatment and/or prophylaxis of diseases, especially bacterial infections.
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- Synthesis of pentafluorophenyl esters of nitroveratryloxycarbonyl-protected amino acids
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For efficient peptide synthesis on a glass chip, 20 kinds of pentafluorophenyl (Pfp) esters of nitroveratryloxycarbonyl (NVOC)-protected amino acids were synthesized by using Pfp trifluoroacetate. Simple purification step gave moderate to high yield. The first loading time of each amino acid on glass surface was 30-60 min. The UV cleavage of the NVOC group was completed within 10 minutes. Georg Thieme Verlag Stuttgart - New York.
- Shin, Dong-Sik,Lee, Yoon-Sik
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experimental part
p. 3307 - 3310
(2010/03/05)
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- Model Compounds of Caged Capsaicin: Design, Synthesis, and Photoreactivity
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Molecules were prepared with substituted nitrobenzyl groups covalently bonded to N-(4-hydroxy-3-methoxybenzyl)acetamide (2) by ether or carbonate linkages. These compounds decomposed under irradiation at 363 nm. Those with carbonate linkages decomposed at
- Katritzky, Alan R.,Xu, Yong-Jiang,Vakulenko, Anatoliy V.,Wilcox, Allan L.,Bley, Keith R.
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p. 9100 - 9104
(2007/10/03)
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- A novel acid-catalyzed isomerization of Aib-containing thiodipeptides
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The use of amino thioacids in the 'azirine/oxazolone method' led to completely epimerized Aib-containing endothiodipeptides (Aib=2- aminoisobutyric acid). It could be established that the epimerization occurred during the acidic hydrolysis of the primaril
- Lehmann, Juerg,Linden, Anthony,Heimgartner, Heinz
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p. 888 - 908
(2007/10/03)
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- Dose-response relations for unnatural amino acids at the agonist binding site of the nicotinic acetylcholine receptor: Tests with novel side chains and with several agonists
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Structure-function relations in the nicotinic acetylcholine receptor are probed using a recently developed method based on chemical synthesis of nonsense suppressor tRNAs with unnatural amino acid residues, site-directed incorporation at nonsense codons in Xenopus laevis oocytes, and electrophysiological measurements. A broad range of unnatural amino acids, as many as 14 at a given site, are incorporated at three sites, α93, α190, and α198, all of which are tyrosine in the wild-type receptor and are thought to contribute to the agonist binding site. Confirming and expanding upon earlier studies using conventional mutagenesis, the three tyrosines are shown to be in substantially different structural microenvironments. In particular, a crucial role is established for the hydroxyl group of α-Tyr93, whereas a variety of substituents are functional at the analogous position of αTyr198. Interestingly, consideration of three different agonists (acetylcholine, nicotine, and tetramethylammonium) does not discriminate between these two best-characterized binding site residues. In addition, double-mutation studies establish the independent effects of mutations at the pore region (second transmembrane region) and at the agonist binding site, and this observation leads to a novel strategy for adjusting EC50 values. These results establish the broad generality and great potential of the unnatural amino acid methodology for illuminating subtle structural distinctions in neuroreceptors and related integral membrane proteins.
- Kearney, Patrick C.,Nowak, Mark W.,Zhong, Wenge,Silverman, Scott K.,Lester, Henry A.,Dougherty, Dennis A.
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p. 1401 - 1412
(2007/10/03)
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