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  • 1
    ISSN: 1075-2617
    Keywords: Multiple synthesis ; optimizing peptide synthesis ; N-terminal asparagine ; BOP ; HATU ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The multipin method of peptide synthesis is demonstrated as a potent methodological tool, where large numbers of comparative studies can be performed concurrently. Two studies are presented. In each study, the test peptides were simultaneously synthesized, and the products examined by high throughput ion spray mass spectrometry and reverse-phase HPLC. In the first study, comprising 24 experiments, peptides 1 (AELFSTHYLAFKEDYSQ-NH2) and 2 (LKDFRVYFREGRDQLWKGPG-NH2) were prepared using Fmoc-Axx/BOP/HOBt/NMM (100: 100: 100: 150 mM) and Fmoc-Axx/HATU/HOAt/NMM (100: 100: 100: 150 mM) with 60.90 and 120 min coupling times. The two reagent combinations were found to give comparable results. The second study compared the N-terminal coupling of Fmoc-Asn-OH, Fmoc-Asn(Mbh)-OH, Fmoc-Asn(Mtt)-OH, Fmoc-Asn(Tmob)-OH and Fmoc-Asn(Trt)-OH in the synthesis of seven test peptides: 3, NVQAAIDYIG-cyclo(Kp); 4, NTVQAAIDYIG-cyclo(KF); 5, NRVYVHPFNL; 6, NRVYVHPFHL: 7, NEAYVHDAPVRSLN: 8, NQLVVPSEGLYLIYSQVLFK. 9, NPNANPNANPNA. A total of 33 experiments were performed. Peptides 3 and 4 were selected to highlight the effect of steric bulk of each Asn derivative on coupling efficiency. Reagent efficiency, as measured by target peptide purity, was as follows: Fmoc-Asn(Tmob)-OH 〉 Fmoc-Asn-OH 〉 Fmoc-Asn(Mtt)-OH = Fmoc-Asn(Trt)-OH 〉 Fmoc-Asn(Mbh)-OH.
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  • 2
    ISSN: 1075-2617
    Keywords: β-amino-alcohol ; statine ; UNCAs ; vicinal tricarbonyl compounds ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: N-Urethane-protected N-carboxyanhydrides (UNCAs) are very reactives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding N-protected β amino alcohols. Reaction of UNCAs with Meldrum's acid, followed by cyclisation, yielded enantiomerially pure tetramic acid derivatives. Diastereoselective reduction of tetramic acid derivatives produced (4S,5S)-N-alkoxycarbonyl-4-hydroxy-5-alkylpyrrolidin-2-ones derived from amino acids, which after hydrolysis yielded statine and statine analogues. Tetramic acid derivatives could also be obtained by reaction of UNCAs with benzyl ethyl followed by hydrogenolytic deprotection and decarboxylation. UNCAs also reacted with phosphoranes to produce the ketophosphorane in excellent yields. Subsequent oxidation with oxone or with [bis(acetoxy)-iodol]-benzene produced vicinal tricarbonyl derivatives. These reactions usually proceeded smoothly and with high yields.
    Additional Material: 4 Ill.
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  • 3
    ISSN: 1075-2617
    Keywords: neoglycopeptides ; solid-phase peptide synthesis ; analgesic glycopeptides ; pilot scale ; preparative purification ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The preparation of a β-galactosylated hydroxyproline derivative and its use in the multi-gram solid-phase synthesis of the potent analgesic neoglycopeptide O1.5-β-D-galactopyranosyl[D-Met2, Hyp5]enkephalinamide is described in this paper. The most closely related impurities have been identified, isolated and characterized. Significant aspects of the synthesis and purification affecting yields and purity of both the building block and the target neoglycopeptide are discussed. © 1997 European Peptide Society and John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 4
    ISSN: 1075-2617
    Keywords: peptides ; neuropeptide ; antimicrobial agent ; skin secretion ; frogs ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The granular dorsal glands of the giant tree frog Litoria infrafrenata contain five peptides including caerulein (a known neuropeptide), and four new peptides named frenatins 1 (MH+ = 1140 Da), 2 (1423), 3 (2180) and 4 (2493). The amino acid sequences of the frenatins are detailed: their structures do not correspond to those of peptides isolated from other amphibians or animals. Frenatin 3, Gly-Leu-Met-Ser-Val-Leu-Gly-His-Ala-Val-Gly-Asn-Val-Leu-Gly- Gly-Leu-Phe-Lys-Pro-Lys-Ser-(OH), has wide spectrum antimicrobial properties.
    Additional Material: 6 Ill.
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  • 5
    ISSN: 1075-2617
    Keywords: Nformylmethionyl peptides ; human neutrophils ; chemotaxis ; superoxide anion generation ; lysozyme release ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formylpeptides formyl-methionyl-Nmethylleucyl- phenylaline methyl ester [for-Met-(NMe)Leu-Phe-OMe] 1, formyl-methionyl-2-aminotetralin-2-carboxyl-phenylalanine methyl ester [for-Met Act-Phe-OMe] 2, formyl-methionyl-1,2,3,4-terahydroisoquinoline-3-carboxl- phenylalanine methyl ester [for-Met-Tic-Phe-OMe] 3 and formyl- methionyl-2-aminoxy-4-methylvaleryl-phenylalanine methyl ester [for-Met-OLeu-Phe-OMe] 4 were synthesized in order to investigate the role of the amide bond at position 2 on biological activities on human neutrophils. Only analogue 2, which keeps the NH group at position 2, was found to retain activity though sterically encumbered.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Peptide Science 2 (1996), S. 157-164 
    ISSN: 1075-2617
    Keywords: sideropore ; peusdobactin ; peusdomycin ; solution-phase peptide synthesis ; unusual amino acids ; Chemistry ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Pseudobactin is a structurally complex and physiologically important siderophore (microbial iron chelator) from Pseudomonas putida- fluorescens. Various fragments of the unusual peptide component of pseudobactin listed below were prepared by solution-phase peptide synthesis.L-Lys· D-threo-β-OH Asp· L-Ala· D-allo-Thr· L-AlaL-Lys· D-threo-βOH Asp· L-Ala· D-allo-ThrD-threo-β-OH Asp· L-Ala· D- allo-Thr· L-Ala· D-N-OH-cycloOrnD-threo-β-OH-Asp· L-Ala· D-allo-Thr· L-AlaL-Ala· D-allo-Thr· L- Ala· D-N-OH-cycloOrnA class of related peptides named pseudomycins have shown promising antifungal activity. To examine if these peptide fragments above would elicit similar activity, the fragments were tested and found to have no antifungal activity in limited bioassays.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 1075-2617
    Keywords: Peptide nucleic acids ; PNA ; PNA synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Peptide nucleic acids (PNA) were synthesized by a modified Merrifield method using several improvements. Activation by O-(benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate in combination with in situ neutralization of the resin allowed efficient coupling of all four Boc-protected PNA monomers within 30 min. HPLC analysis of the crude product obtained from a fully automated synthesis of the model PNA oligomer H-CGGACTAAGTCCATTGC-Gly-NH2, indicated an average yield per synthetic cycle of 97.1%. N1-benzyloxycarbonyl-N63-methylimidazole triflate substantially outperformed acetic anhydride as a capping reagent. The resin-bound PNAs were successfully cleaved by the ‘low-high’ trifluoromethanesulphonic acid procedure.
    Additional Material: 4 Ill.
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  • 8
    ISSN: 1075-2617
    Keywords: Opioid bioactivities ; bioactive conformations ; NMR studies ; molecular modelling ; synthesis of cyclic opioids ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Our continuing efforts to study structure-activity relationships of peptide opioids have resulted in the synthesis of a series of cyclic opioids related to dermorphins and deltorphins. The biological activities of the compounds have been determined and the conformational analyses carried out using 1H-NMR spectroscopy and molecular modelling. The three compounds in the series Tyr-c[D-Orn-Phe-Ala], Tyr-c[D-Lys-Phe-Ala], and Tyr-c[A2Bu-Phe-Ala-Leu] are cyclized via a lactam bridge from the side-chain of the residue at the second position with the carboxyl terminus of each compound. The molecules incorporate 12-, 13- and 14-membered rings, respectively. They include a phenylalanine at the third position which is a distinguishing characteristic of dermorphins and deltorphins. The guinea pig ileum and mouse vas deferens assays show that the compounds are highly active at both μ- and δ-opioid receptors. The compounds are all highly effective antinociceptive agents as measured by the intrathecal rat hot plate test. Conformational analyses of the molecules indicate that they can adopt topochemical arrays required for bioactivity at both μ- and δ-receptors which explains their high activity in both guinea pig ileum and mouse vas deferens in vitro assays. The results support our models for μ- and δ-receptor activity for constrained peptide opioids.
    Additional Material: 5 Ill.
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  • 9
    ISSN: 1075-2617
    Keywords: Immunomodulators ; lipopeptides ; peptide synthesis ; S-[2,3-dihydroxypropyl]-cysteine ; splenocyte activators ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Various lipopeptides representing the N-terminal part of the cytochrome subunit of the photosynthetic reaction centre from the purple bacterium Rhodopseudomonas virdis were prepared by solid-phase peptide synthesis. These lipopeptides consisted of a S-[2,3-dihydroxypropyl]-cysteinyl (Dhc) residue N-terminally coupled to the nonapeptide FEPPPATTT. Different numbers of palmitoyl (Pam) chains were attached to Dhc via ester and/or amide bonds. The lipopeptide Dhc(Pam)2-FEPPPATTT containing two ester-bonded palmitoyl residues and a free N-chain lipopeptide Pam-Dhc(Pam)-FEPPPATTT containing one amide- and one ester-bonded palmitoyl residues, the two-chain lipopeptide Pam-Dhc(Pam)-FEPPPATTT containing one amide- and one ester-bonded palmitoyl residue, and the N-terminally elongated lipopeptide SLVAG-Dhc(Pam)2-FEPPPATTT were less active. The nonapeptide FEPPPATTT and the decapeptide Dhc-FEPPPATTT were only merginal splenocyte activators, even at concentrations as high as 1 μM. Thus, lipopeptide Dhc(Pam)2-FEPPPATTT constitutes the first potent splenocyte stimulating Dhc-lipopeptide described so far that contains only two fatty acid residues.
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  • 10
    ISSN: 1075-2617
    Keywords: Peptide amide ; amide anchors ; intermediates in peptide amide synthesis ; cleavage of peptide amides ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cleavage and kinetic studies have been carried out using commercially obtained H-Tyr(tBu)-5-(4′-aminomethyl-3′,5′-dimethoxyphenoxy)valeric acid-TentaGelS (H-Tyr(tBu)-4-ADPV-TentaGelS) and H-Tyr (tBu)-4-ADPV-Ala-aminomethyl-resin (H-Tyr(tBu)-4-ADPV-AM-resin) prepared from commercially available resin and loaded with commercially available Fmoc-4-ADPV-OH amide anchor. Cleavage with pure trifluoroacetic acid (TFA) gave the intermediate H-Tyr-4-ADPV-NH2, which was then degraded to H-Tyr-NH2, and cleavage with TFA/dichloromethane (1:9) yielded H-Tyr-4-ADPV-NH2 which could be isolated in preparative amounts. Cleavage reactions with 15N-labelled H-Ala-4-ADPV-[15N]-Gly-AM-resin yielded the intermediate H-Ala-4-ADPV-NH2, which contained no 15N as demonstrated by 1H-NMR. The analysis of the commercial Fmoc-4-ADPV-OH amide anchor showed the presence of Fmoc-4-ADPV-4-ADPV-OH as an impurity in high amounts. This dimeric anchor molecule is the cause of formation of the anchor-linked peptide intermediate obtained during the cleavage from the resin. The particularly high acid-lability of the amide bond between the two ADPV moieties was utilized to synthesize sidechain and C-terminally 4-ADPV protected pentagastrin on a double-anchor resin, and to cleave it using 5% trifluoroacetic acid in dichloromethane. This method may offer a new way for the synthesis of protected peptide amides with improved solubility to be used in fragment condensation.
    Additional Material: 7 Ill.
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