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Peptide Chemistry (peptide + chemistry)

Distribution by Scientific Domains

Chemistry	83%

Selected Abstracts

Oxime Carbonates: Novel Reagents for the Introduction of Fmoc and Alloc Protecting Groups, Free of Side Reactions

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 17 2010
Sherine N. Khattab
Abstract Fmoc and Alloc protecting groups represent a consistent alternative to classical Boc protection in peptide chemistry. The former was established in the last decades as the ,-amino protecting group of choice, whereas the latter allows a fully orthogonal protection strategy with Fmoc and Boc. Usually, the introduction of the Fmoc and Alloc moieties takes place through their halogenoformates, azides, or activated carbonates. This rather simple reaction is accompanied by several side reactions, specially the formation of Fmoc/Alloc dipeptides and even tripeptides. The present work describes new promising Fmoc/Alloc-oxime reagents, which are easy to prepare, stable, and highly reactive crystalline materials that afford almost contaminant-free Fmoc/Alloc-amino acids in high yields by following a conventional procedure. Amongst the Fmoc-oxime derivatives, the N -hydroxypicolinimidoyl cyanide derivative (N -{[(9H-fluoren-9-yl)methoxy]carbonyloxy}picolinimidoyl cyanide) gave the best results for the preparation of Fmoc-Gly-OH, which is the most predisposed to give side reactions. The same Alloc-oxime analogue afforded the preparation of Alloc-Gly-OH in good yield, purity, and extremely low dipeptide formation, as analyzed by reverse-phase HPLC and NMR spectroscopy. [source]

Syntheses of Triostin A Antibiotic and Nucleobase-Functionalized Analogs as New DNA Binders

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 28 2009
Anmol Kumar Ray
Abstract A total synthesis of the natural product triostin A, wherein the N -methylated depsipeptide scaffold is constructed by solution-phase peptide chemistry followed by disulfide formation and macrocyclization, is described. Finally, the quinoxalines were attached to provide the DNA bisintercalator. Analogs of triostin A were obtained by the successive functionalization of the cyclic depsipeptide with pyrimidine or purine recognition units. The attachment of functional units was achieved by the orthogonal protection of the respective side chain amino functionalities. The nucleobase-functionalized triostin analogs have the potential to recognize double-stranded DNA by hydrogen bonding. The interaction with DNA was investigated by UV spectroscopy and fluorescence intercalator displacement. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]

Characterization of conantokin Rl -A: molecular phylogeny as structure/function study

JOURNAL OF PEPTIDE SCIENCE, Issue 8 2010
Konkallu H. Gowd
Abstract A multidisciplinary strategy for discovery of new Conus venom peptides combines molecular genetics and phylogenetics with peptide chemistry and neuropharmacology. Here we describe application of this approach to the conantokin family of conopeptides targeting NMDA receptors. A new conantokin from Conus rolani, ConRl -A, was identified using molecular phylogeny and subsequently synthesized and functionally characterized. ConRl -A is a 24-residue peptide containing three ,-carboxyglutamic acid residues with a number of unique sequence features compared to conantokins previously characterized. The HPLC elution of ConRl -A suggested that this peptide exists as two distinct, slowly exchanging conformers. ConRl -A is predominantly helical (estimated helicity of 50%), both in the presence and absence of Ca++. The order of potency for blocking the four NMDA receptor subtypes by ConRl -A was NR2B > NR2D > NR2A > NR2C. This peptide has a greater discrimination between NR2B and NR2C than any other ligand reported so far. In summary, ConRl -A is a new member of the conantokin family that expands our understanding of structure/function of this group of peptidic ligands targeted to NMDA receptors. Thus, incorporating phylogeny in the discovery of novel ligands for the given family of ion channels or receptors is an efficient means of exploring the megadiverse group of peptides from the genus Conus. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. [source]

Diketopiperazines in peptide and combinatorial chemistry

JOURNAL OF PEPTIDE SCIENCE, Issue 1 2003
Dr Peter M. Fischer
Abstract Diketopiperazines (DKPs), the smallest cyclic peptides, represent an important class of biologically active natural products and their research has been fundamental to many aspects of peptide chemistry. The advent of combinatorial chemistry has revived interest in DKPs for two reasons: firstly, they are simple heterocyclic scaffolds in which diversity can be introduced and stereochemically controlled at up to four positions; secondly, they can be prepared from readily available ,-amino acids using very robust chemistry. Here synthetic methods, conformation, as well as applications of DKPs are summarized and discussed critically. Copyright © 2003 European Peptide Society and John Wiley & Sons, Ltd. [source]

Primary structural determination of N-terminally blocked peptides from the bark of Eucommia ulmoides Oliv by mass spectrometric analysis

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 9 2003
Ren-Huai Huang
Sequencing of N-terminally blocked proteins/peptides is a challenge since these molecules inhibit processing by Edman degradation. By using high accuracy Fourier transform ion cyclotron resonance (FTICR) tandem mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), the primary structures of two novel N-terminally blocked antifungal peptides (EAFP1 and EAFP2), purified from the bark of Eucommia ulmoides Oliv, have been determined. The results show that the high mass accuracy provided by FTICR mass spectrometry is effective to determine the N-terminally blocking group, and can simplify the task of spectral interpretation and improve the precision of sequence determination. The combination of MALDI-TOFMS with carboxyl peptidase Y digestion was used to determine the C-terminal 36- and 27-residue sequences of EAFP1 and EAFP2, respectively, to provide the sequence linkage information for tryptic fragments. Compared with traditional peptide chemistry the advantage of mass spectrometric techniques is their simplicity, speed and sensitivity. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Synthesis and biological evaluation of destruxin A and related analogs

CHEMICAL BIOLOGY & DRUG DESIGN, Issue 1 2001
T. Ast
Abstract: This report describes the development of an efficient solid-phase synthesis protocol and adaptation of reported solution phase procedures for the synthesis of the cyclic depsihexapeptide destruxin A and related analogs. The solid-phase method described is based on standard Fmoc peptide chemistry, including a new synthetic method for the assembly of the depsi bond-containing unit. In order to select analogs of destruxin A for synthesis and evaluation of insecticidal activity, the work of Hellberg et al., describing a set of Z -descriptors for amino acid side-chains comparing their physicochemical properties, was utilized. Destruxin A and 27 different analogs with structural variations in four residues were synthesized and insecticidal activity was evaluated via injections into tobacco budworm (Heliothis virescens) larvae. Several destruxin A analogs were found to be at least as potent as the native compound. [source]