Search results for "Tripeptide"
showing 10 items of 33 documents
The young hard active Sun: soft X-ray irradiation of tryptophan in water solutions
2010
AbstractThe X-ray emission of the young Sun was much harder and intense than today and might have played a significant role in the evolution of complex organics in protoplanetary environments. We investigate the effects of soft X-rays on tryptophan molecules in aqueous solutions at room temperature. As results of the irradiation experiments we detect several light species indicative of fragmentation, together with large molecular structures such as tryptophan dipeptide and tripeptide. Complexification is more evident in H2O solution than in D2O, probably due to isotopic effects. The abundances of peptides depend on the irradiation dose and decrease with increasing energy deposition. Radical…
Straightforward Stereoselective Access to Cyclic Peptidomimetics
2009
The preparation of cyclic dipeptide mimetics from chiral imino lactones derived from (R)-phenylglycinol is described. Key steps of the synthetic route included the fully stereoselective construction of a quaternary center, the formation of six-, seven-, or eight-membered lactams by means of an RCM cyclization, and the introduction of a new amino group within the lactam ring. The synthesis of a tripeptide mimetic is also reported.
Synthesis of peptides with α,β‐dehydroamino acids, V. coupling experiments with C‐terminal dehydrophenylalanine and dehydroalanine residues
1986
N-Protected model dipeptides of C-terminal (Z)-ΔPhe and ΔAla couple with glycine esters after activation with either diphenyl phosphorazidate (DPPA), N-cyclohexyl-N′-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate (WSC), N,N′-dicyclohexylcarbodiimide + 1-hydroxybenzotriazole (DCC + HOBt), or the mixed anhydride (MA) with isobutyl chlorocarbonate to give in good or mostly moderate yields the (Z)-ΔPhe-containing tripeptides 1 – 9 and ΔAla-containing tripeptides 11 – 19, respectively. In the MA and DPPA methods, further acylation products 20a – d are formed to a great extent, expecially during the ΔAla peptide syntheses. (E)-TFA-Gly-ΔPhe and Gly-OtBu, irrespective of the activati…
Hypusinated eIF5A is required for the translation of collagen.
2021
ABSTRACT Translation of mRNAs that encode peptide sequences with consecutive prolines (polyproline) requires the conserved and essential elongation factor eIF5A to facilitate the formation of peptide bonds. It has been shown that, upon eIF5A depletion, yeast ribosomes stall in polyproline motifs, but also in tripeptide sequences that combine proline with glycine and charged amino acids. Mammalian collagens are enriched in putative eIF5A-dependent Pro-Gly-containing tripeptides. Here, we show that depletion of active eIF5A in mouse fibroblasts reduced collagen type I α1 chain (Col1a1) content, which concentrated around the nuclei. Moreover, it provoked the upregulation of endoplasmic reticul…
Design, Synthesis, and Evaluation of New Tripeptides as COX-2 Inhibitors
2013
Cyclooxygenase (COX) is a key enzyme in the biosynthetic pathway leading to the formation of prostaglandins, which are mediators of inflammation. It exists mainly in two isoforms COX-1 and COX-2. The conventional nonsteroidal anti-inflammatory drugs (NSAIDs) have gastrointestinal side effects because they inhibit both isoforms. Recent data demonstrate that the overexpression of these enzymes, and in particular of cyclooxygenases-2, promotes multiple events involved in tumorigenesis; in addition, numerous studies show that the inhibition of cyclooxygenases-2 can delay or prevent certain forms of cancer. Agents that inhibit COX-2 while sparing COX-1 represent a new attractive therapeutic deve…
Synthese von Giycopeptiden: Selektive C-terminale Deblockierung und Peptidkettenverlängerung an Glucosylserin-Derivaten
1983
Benzyloxycarbonyl-(Z-)serin-2-bromethylester (3b) wird mit 2,3,4,6-Tetra-O-benzoyl-α-D-gluco-pyranosylbromid (14) zum Glucosylserinester 15 verknupft. Nach Umwandlung in den entsprechenden 2-Iodethylester 23 wird die Carboxygruppe durch Eliminierung mit Zink selektiv deblockiert. Dabei bleiben die Z- und die Kohlenhydrat-Schutzgruppen sowie die empfindliche O-glycosidische Bindung unverandert erhalten. Das Glycosyl-Z-serin 24 reagiert mit Aminosaure-2-bromethylestern 2 zu geschutzten Glycodipeptid-2-bromethylestern 18, die nach selektiver Carboxydeblockierung zu Glycotripeptidestern 25 C-terminal verlangert werden. Wahrend geschutzte Serin-Dipeptide 5 mit 14 zu Konjugaten 18 glycosyliert we…
Conformation of tert-butoxycarbonylglycyl-dehydroalanyl-glycine methyl ester in the crystalline state and calculated in the gas phase.
2006
tert-Butoxycarbonylglycyl-dehydroalanyl-glycine methyl ester (systematic name: methyl {2-[(tert-butoxycarbonylamino)acetamido]prop-2-enamido}acetate) (Boc0-Gly1-ΔAla2-Gly3-OMe), C13H21N3O6, has been structurally characterized by single-crystal X-ray diffraction and by density functional theory (DFT) calculations at the B3LYP/6–311+G** level. The peptide chain in both the solid-state and calculated structures adopts neither β nor γ turns. All amino acid residues in the tripeptide sequence are linked trans to each other. The bond lengths and valence angles of the amino acid units in the crystal structure and gas phase are comparable. However, the conformation of the third glycyl residue (…
ChemInform Abstract: New Ionic Liquid-Modified Silica Gels as Recyclable Materials for L-Proline- or H-Pro-Pro-Asp-NH2-Catalyzed Aldol Reaction.
2008
L-proline and the tripeptide H–Pro–Pro–Asp–NH2 (1) have been supported, by adsorption, onto the surface of modified silica gels functionalized with a monolayer of covalently attached 1,2-dimethyl-imidazolium chloride, tetrafluoroborate or hexafluorophosphate ionic moieties, respectively. Three different linkers were used to attach the ionic liquid moiety to the surface of these supports. The resulting materials have been used as catalysts for the aldol reaction between acetone and several substituted benzaldehydes. Good yields and enantioselectivities, comparable to or better than those obtained under homogeneous conditions, were obtained. These materials are easily recovered by filtration,…
Oligopeptide der β-Carbolin-3-carbonsäure - Synthese und Affinität zu Benzodiazepinrezeptoren
1987
Es wurden Oligopeptide der β-Carbolin-3-carbonsaure dargestellt und deren Affinitat zum Benzodiazepinrezeptor in Mausehirn-Membranen bestimmt. Uber Struktur-Affinitatsbeziehungen wird berichtet. Oligopeptides of β-Carboline-3-carboxylic Acid - Synthesis and Benzodiazepine Receptor Affinity Oligopeptides of β-carboline-3-carboxylic acid were prepared and tested with respect to their affinity for the benzodiazepine receptor in mouse brain membranes. Structure-affinity relationships are reported.
Crystal structure of the tripeptideN-(benzyloxycarbonyl)glycylglycyl-L-norvaline
2015
The title tripeptide, C17H23N3O6, contains a nonproteinogenic C-terminal amino acid residue, norvaline, which is an isomer of the amino acid valine. Norvaline, unlike valine, has an unbranched side chain. The molecule has a Gly–Gly segment which adopts an extended conformation. The norvaline residue also adopts an extended backbone conformation while its side chain has ag+tconformation. In the crystal lattice, N—H...O and O—H...O hydrogen bonds stabilize the packing. Molecules translated along the crystallographicaaxis associate through an N—H...O hydrogen bond. The remaining three hydrogen bonds are between molecules related by a21screw axis.