Search results for "Tripeptide"
showing 10 items of 33 documents
Release of free amino acids upon oxidation of peptides and proteins by hydroxyl radicals
2017
Hydroxyl radical-induced oxidation of proteins and peptides can lead to the cleavage of the peptide, leading to a release of fragments. Here, we used high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and pre-column online ortho-phthalaldehyde (OPA) derivatization-based amino acid analysis by HPLC with diode array detection and fluorescence detection to identify and quantify free amino acids released upon oxidation of proteins and peptides by hydroxyl radicals. Bovine serum albumin (BSA), ovalbumin (OVA) as model proteins, and synthetic tripeptides (comprised of varying compositions of the amino acids Gly, Ala, Ser, and Met) were used for reactions with hydroxyl ra…
Identification of noncovalent proteasome inhibitors with high selectivity for chymotrypsin-like activity by a multistep structure-based virtual scree…
2016
Noncovalent proteasome inhibitors introduce an alternative mechanism of inhibition to that of covalent inhibitors, e.g. carfilzomib, used in cancer therapy. A multistep hierarchical structure-based virtual screening (SBVS) of the 65,375 NCI lead-like compound library led to the identification of two compounds (9 and 28) which noncovalently inhibited the chymotrypsin-like (ChT-L) activity (Ki = 2.18 and 2.12 μM, respectively) with little or no effects on the other two major proteasome proteolytic activities, trypsin-like (T-L) and post-glutamyl peptide hydrolase (PGPH) activities. A subsequent hierarchical similarity search over the full NCI database with the most active tripeptide-based inh…
New Fluorinated Peptidomimetics through Tandem Aza-Michael Addition to α-Trifluoromethyl Acrylamide Acceptors: Synthesis and Conformational Study in …
2009
A range of partially modified retro (PMR) psi[NHCH(2)] peptide mimetics containing a hydrolytically stable CH(2)CH(CF(3))CO unit have been synthesized. The first kind of peptidomimetics is obtained from the highly efficient aza-Michael addition of different amines to alpha-trifluoromethyl acrylamide acceptors. Subsequent deprotection of the amino group furnishes the key common intermediate for the synthesis of other families of peptidomimetics: dipeptides, tripeptides, peptidomimetics containing a urea moiety, and structures containing two units of alpha-trifluoromethyl-beta(2)-alanine. Finally, a conformational study of several of the newly synthesized peptidomimetics, performed with the a…
Migration of Leukocytes into Filters Coated Homogeneously with Immune Complexes, Antigens, Lectins or Tripeptides
1980
Cellulose nitrate filters were incubated in solutions of albumin, a chemotactically active tripeptide (f-Met-Leu-Phe), immune complexes or lectins and afterwards washed with buffer. They showed a dose-dependent increased leukocyte migration, when tested in typical Boyden chambers in comparison to filters treated only with buffer. The tripeptide, the immune complexes and the lectins were stimulatory at very low concentrations and acted inhibitory at high concentrations. Treating filters with formaldehyde or glutardialdehyde had no clear stimulatory effect. These findings extend earlier observations obtained with casein. They show that cells move very effectively on solid substrata in the abs…
Synthesis and activity of phosphinic tripeptide inhibitors of cathepsin C
2004
Phosphinic tripeptide analogues Gly-Xaaψ[P(O)(OH)CH2]-Gly have been developed as inhibitors of cathepsin C (DPP I), a lysosomal, papain-like cysteine protease. The target compounds were synthesised by addition of methyl acrylate to the appropriate phosphinic acids followed by the N-terminus elongation using mixed anhydride procedure. The latter step has been demonstrated to be a suitable method for N-terminal extension of the phosphinic pseudopeptide analogues without requirement of hydroxyphosphinyl protection. The title compounds appeared to be moderate inhibitors of the cathepsin C. However, although designed as transition state analogues, they surprisingly exhibited noncompetitive mode …
The infrared and Raman spectra of solid tridehydropeptides : influence of ΔAla and ΔPhe on the spectral profile
2012
Abstract A series of solid tripeptides Boc-Gly-X-Gly-OMe (X = dehydroalanine (ΔAla), dehydrophenylalanine (ΔPhe)) was investigated by Raman scattering and Fourier transform infrared spectra to examine the conformational marker bands of the unsaturated residue. The observed fundamental modes gave us the opportunity to analyze structural features that change due to the substitution of Ala by ΔAla and due to the different spatial arrangement of ΔPhe ( Z and E isomers). In addition, we showed the alteration of the spectral profile when the large size residue (Phe) is introduced into the backbone of the peptide with ΔPhe (in Boc-Gly-Δ (Z) Phe-Phe-OMe). The frequency ranges of interest included t…
Synthese vonN-Glycopeptid-Partialstrukturen der Verknüpfungsregion sowohl der Transmembran-Neuraminidase eines Influenza-Virus als auch des Faktors B…
1989
Mit Hilfe der Schutzgruppenkombination Boc-Gruppe/Allylester und Acetylschutz im Kohlenhydratteil wurden die geschutzten N-Chitobiosyl-asparagin-peptide 12a und 14 synthetisiert, die der Verknupfungsregion des Faktors B des menschlichen Komplementsystems und einer Influenza-Virus-Neuraminidase entsprechen. Aus dem vollgeschutzten Glycopeptid 12a liesen sich der Allylester und die Acetylschutzgruppen simultan mit methanolischem Ammoniak und die Boc-Schutzgruppe mit wasserfreier Trifluoressigsaure ohne storende Nebenreaktionen entfernen. Versuche, die Boc-Gruppe aus an den Kohlenhydrat-Hydroxyfunktionen deblockierten Glycopeptiden abzulosen, fuhrten uberwiegend zur Spaltung der O-glycosidisch…
Enhanced β-turn conformational stability of tripeptides containing Δphe in cis over trans configuration
2013
Conformations of three pairs of dehydropeptides with the opposite configuration of the Delta Phe residue, Boc-Gly-Delta(Z/E)Phe-Phe-p-NA (Z- p -NA and E- p -NA), Boc-Gly-Delta(Z/E)Phe-Phe-OMe (Z-OMe and E-OMe), and Boc-Gly-Delta(Z/E)Phe-Phe-OH (Z-OH and E-OH) were compared on the basis of CD and NMR studies in MeOH, TFE, and DMSO. The CD results were used as the additional input data for the NMR-based calculations of the detailed solution conformations of the peptides. It was found that Z- p -NA, E- p -NA, Z-OMe, and Z-OH adopt the beta-turn conformations and E-OMe and E-OH are unordered. There are two overlapping type III beta-turns in Z- p -NA, type II' beta-turn in E- p -NA, and type II …
Influence of solvents on conformation of dehydropeptides
2013
Abstract Structural investigations of dehydropeptides containing (Z)-dehydrophenylalanine in solvents characterized by different polarity are discussed. The conformational analysis are based on spectroscopic methods (NMR, CD), molecular modeling techniques and in case of the tripeptide, ab initio methods. The results of temperature experiment indicate, that the only conformation of the investigated hexapeptide 3 is stabilized by intramolecular hydrogen bonds. Depending on the length of the peptide chain, the polarity of solvent influences on arrangement of the side chain of the amino acids or of the main chain of the peptide.
Poly(ethylene glycol-co-allyl glycidyl ether)s: a PEG-based modular synthetic platform for multiple bioconjugation.
2011
A series of random copolymers comprising ethylene oxide (EO) and 0-100% allyl glycidyl ether (AGE) has been prepared by anionic ring-opening polymerization with molecular weights between 5000 and 13,600 g/mol and polydispersity indices in the range of 1.04-1.19. As key for the homogeneity of the PEG conjugates, real-time ¹H NMR polymerization kinetics, ¹³C NMR analysis of triad sequence distribution, and analysis of the thermal behavior by differential scanning calorimetry (DSC) revealed a distinctive random copolymer structure. Via thiol-ene coupling (TEC), showing mainly "click" characteristics and nearly quantitative yields, PEG derivatives with multiple amino, carboxy, or hydroxy functi…