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Search for "peptides" in Full Text gives 382 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules
Beilstein J. Org. Chem. 2018, 14, 2163–2185, doi:10.3762/bjoc.14.190
- lasso, a structural motif which was also recently found in nature for peptides with high antibacterial efficacy [71]. In 12, the TTF molecule is not implemented in the thread but in the wheel component. In the neutral state, strong hydrogen bonding between the crown ether wheel and the dialkylammonium
Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry
Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179
- -trifluoromethylamines, which are attractive due to their low basicity, ability to act as amide bioisosteres [42] and higher metabolic stability. The number of medicinal chemists who specialise in peptides has been increasing in recent years. This is largely due to the increasing interest in macrocyclic peptides. A key
- structural characteristic of peptides is the disulfide bridge formed by cysteines. This functional group is much more prevalent in peptide medicinal chemistry. Noël et al. have published a protocol for the aerobic oxidation of thiols to disulfides, using Eosin Y photocatalysis and TMEDA (Scheme 3) [43]. The
- , in a similar manner to the amide coupling by Leow. The demonstrated oxidation of the free thiols to a disulfide to afford oxytocin (3c) as the product in quantitative yield shows the value of this procedure. Medicinal chemists who specialise in creating artificial peptides could find much use for
Artificial bioconjugates with naturally occurring linkages: the use of phosphodiester
Beilstein J. Org. Chem. 2018, 14, 1946–1955, doi:10.3762/bjoc.14.169
- ’-phosphitylation; phosphodiester bonds; Introduction Peptides and oligonucleotides are of exceptional importance since they are promising pharmaceutical candidates for the treatment of a range of diseases that are beyond traditional small molecule drugs [1][2][3][4][5][6][7]. Due to their iterative structures
- artificial building blocks with various functions are available, expanding chemical libraries of peptides and oligonucleotides significantly [8][9][10][11][12][13][14][15]. Furthermore, thus designed and synthesized peptides and oligonucleotides can be conjugated with each other to integrate their
- solvents, and washing the precipitates with polar solvents simultaneously rinses away excess amino acids or nucleosides and coupling reagents. We have demonstrated multistep syntheses of up to 28-mers for peptides and 21-mers for oligonucleotides without column purification. In all cases, the C-terminal
Diazirine-functionalized mannosides for photoaffinity labeling: trouble with FimH
Beilstein J. Org. Chem. 2018, 14, 1890–1900, doi:10.3762/bjoc.14.163
- -functionalized mannosides as high-affinity FimH ligands and performed an extensive study on photo-crosslinking of the best ligand (mannoside 3) with a series of model peptides and FimH. Notably, we have employed high-performance mass spectrometry to be able to detect radiation results with the highest possible
- labeling studies with more complex substrates. Irradiation of mannoside 3 and model peptides In analogy to our earlier work, we first used a series of model peptides (M2, M3, M7, M8, T3, and S17, cf. Table 2) for the photolabeling experiments with mannoside 3. These model peptides were chosen rather
- the peptides in a 1:1 ratio. After irradiation with UV light, two new signals were detected in nano-LC–ESIMS experiments in comparison to the original peptide spectra (Table 2). It should be noted that whereas we could monitor photodecomposition of the photolabels by 19F NMR spectroscopy (cf. [29
A hemicryptophane with a triple-stranded helical structure
Beilstein J. Org. Chem. 2018, 14, 1885–1889, doi:10.3762/bjoc.14.162
- a better understanding of the properties of this biological system and giving rise to numerous applications ranging from artificial collagenous biomaterials to peptides for therapeutic uses [3][4][5]. Recently, molecular cages presenting a triple helical structure have aroused a considerable
Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae
Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151
- the CSP signal that they produce (CSP1 and CSP2, Figure 1) and their cognate receptors (ComD1 and ComD2, respectively), with minimal cross-talk between the groups [28]. The two CSP signals share approximately 50% homology and differ mainly in hydrophobic residues in the central region of the peptides
- (in addition to upregulation of ComX). ComD modulation can therefore be quantified by measuring β-gal activity. The peptides were first screened for their ability to activate/inhibit the ComD1 and ComD2 receptors at high concentration (10 µM). Only analogs that exhibited greater than 75% activation
- of 0.2 M. Reactions were run at 50 W at a temperature of 75 °C for 8 minutes, followed by 2 × 3 min deprotection with 20% piperidine in DMF. Peptide purification. Crude peptides were purified with RP-HPLC. The crude peptide was dissolved in ACN/H2O (1:4) and purified in 2.0–2.4 mL portions on either
Synthesis and photophysical studies of a multivalent photoreactive RuII-calix[4]arene complex bearing RGD-containing cyclopentapeptides
Beilstein J. Org. Chem. 2018, 14, 1758–1768, doi:10.3762/bjoc.14.150
- is also faced by complexes anchored on cell-penetrating peptides. In order to provide a selective cell targeting, we developed a multivalent system composed of a photoreactive ruthenium(II) complex tethered to a calix[4]arene platform bearing multiple RGD-containing cyclopentapeptides. Extensive
- reactive-oxygen-species-dependent apoptosis. Another strategy for the design of cell penetrating photoreactive RuII complexes consists of tethering the complex to a vector that allows a cellular uptake. In this context, OsII, RhIII and RuII complexes were anchored to cell penetrating peptides (CPP) such as
- the Ru complex and the cyclic peptides by the calixarene should be an advantage by preventing any negative effect of the RGD peptidic units on the photochemistry of the complex and, alternatively, prevents any influence of the complex on the affinity of the RGD patterns to interact with the targeted
Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit
Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145
- s-triazine units (branch-cells, T-0 or cores T-2, Scheme 3 and Scheme 4). According to H. Kessler (in 1982, [62]), this parameter is appropriate for describing amide protons solvation in p→π conjugated systems, such as –N(H)–C(=O)– ↔ –N+(H)=C(–O−)– in peptides and proteins, in water. Later on (in
Natural and redesigned wasp venom peptides with selective antitumoral activity
Beilstein J. Org. Chem. 2018, 14, 1693–1703, doi:10.3762/bjoc.14.144
- membranes increased significantly when treated with lead peptides compared to controls. Biophysical features such as helicity, hydrophobicity, and net positive charge were identified to play an important role in the anticancer activity of the peptides. Indeed, abrupt changes in peptide hydrophobicity and
- conformational propensity led to peptide inactivation, whereas increasing the net positive charge of peptides enhanced their activity. We present peptide templates with selective activity towards breast cancer cells that leave normal cells unaffected. These templates represent excellent scaffolds for the design
- of selective anticancer peptide therapeutics. Keywords: breast cancer; decoralin; MCF-7 cells; peptide design; selective anticancer peptides; structure–activity relationships; Introduction Approximately 12% of U.S. women develop breast cancer according to the U.S. Breast Cancer website (http
β-Hydroxy sulfides and their syntheses
Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143
- 80 °C, xylene; (3) TFA, CH2Cl2, followed by HPLC separation of 7 and 126. Synthesis of peptides containing a β-hydroxy sulfide moiety. Synthesis of diltiazem (12) using biocatalytic resolution of an epoxide followed by thiolysis. Acknowledgements This review was made possible by funding provided by
Drug targeting to decrease cardiotoxicity – determination of the cytotoxic effect of GnRH-based conjugates containing doxorubicin, daunorubicin and methotrexate on human cardiomyocytes and endothelial cells
Beilstein J. Org. Chem. 2018, 14, 1583–1594, doi:10.3762/bjoc.14.136
- potentially increases the tumor selectivity of drugs and decreases their cardiotoxicity. Increased expression of gonadotropin-releasing hormone (GnRH) receptors on the surface of tumor cells has been reported. Thus, the attachment of the aforementioned chemotherapeutic drugs to GnRH-based peptides may result
- . Small peptides that recognize target receptors on tumor cells might be suitable targeting moieties for this purpose. Hormone peptides, in particular, GnRH and somatostatin derivatives that possess antiproliferative effect on their own, are among the best candidates as homing peptides [10]. A.V. Schally
- used for amide bond formation. The difference between Dox and Dau is the lack of the primary OH group in the case of the latter one. Therefore, Dau cannot be attached to peptide carriers via an ester bond. Mtx contains a glutamic acid whose carboxyl groups are suitable for the attachment to peptides
Design and biological characterization of novel cell-penetrating peptides preferentially targeting cell nuclei and subnuclear regions
Beilstein J. Org. Chem. 2018, 14, 1378–1388, doi:10.3762/bjoc.14.116
- Anja Gronewold Mareike Horn Ines Neundorf Department of Chemistry, Biochemistry, University of Cologne, Zuelpicher Str. 47a, 50674 Cologne, Germany 10.3762/bjoc.14.116 Abstract Within this study, we report about the design and biological characterization of novel cell-penetrating peptides (CPPs
- peptides, N50-sC18* and NrTP-sC18*, and found that they are nontoxic up to a concentration of 50 or 100 µM depending on the cell lines used. Moreover, detailed cellular uptake studies revealed that both peptides enter cells via energy-independent uptake, although endocytotic processes cannot completely
- excluded. However, initial drug delivery studies demonstrated the high versatility of these new peptides as efficient transport vectors targeting specifically nuclei and nucleoli. In future, they could be further explored as parts of newly created peptide–drug conjugates. Keywords: anticancer drugs; cell
Oligonucleotide analogues with cationic backbone linkages
Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111
- aspired improvement of cellular uptake, fully cationic oligonucleotide analogues might also be attractive candidate structures, as indicated by the advantageous properties of cationic cell-penetrating peptides (CPPs) [38]. However, the design of modifications of type 1–6 precludes the preparation of fully
Recyclable hypervalent-iodine-mediated solid-phase peptide synthesis and cyclic peptide synthesis
Beilstein J. Org. Chem. 2018, 14, 1112–1119, doi:10.3762/bjoc.14.97
- ) reagent FPID and (4-MeOC6H4)3P was successfully applied to solid-phase peptide synthesis and cyclic peptide synthesis. Four peptides with biological activities were synthesized through SPPS and the bioactive cyclic heptapeptide pseudostellarin D was obtained via solution-phase peptide synthesis. It is
- , and it plays a crucial role in the elaboration and composition of biological systems. Amide bonds are widely present not only in peptides and proteins but also in pharmaceuticals and many natural products. Among the methods for amide bond formation, the direct condensation of carboxylic acids and
- test whether the FPID/(4-MeOC6H4)3P system can be used in SPPS. We selected the commercially available 2-chlorotrityl chloride resin (2-Cl-Trt-Cl resin) as the solid support and [(9-fluorenylmethyl)oxy]carbonyl (Fmoc) as the α-amino protecting group. The peptides were synthesized following the route as
Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle
Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87
- and peptides [23][24][25]. Numerous examples of five-membered hypervalent iodine(III) heterocycles containing other than oxygen heteroatoms, such as sulfur [26], boron [27][28], phosphorous [29], or nitrogen [30][31][32], have been synthesized and characterized by X-ray crystallography. In particular
On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site
Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80
- throughout this review. Among the most intriguing navigating delivery systems that can combine the transporting vehicle and the navigating/targeting moiety in a single module are the tumor-homing peptides [32]. These peptides are exploited to assemble the peptide–drug conjugates (PDCs) which are considered
- attention since peptides can be easily produced in large quantities and their purification is simple. Moreover, an array of different tumor-targeting peptides has been discovered [32] for multifarious types of cancer. This bountiful palette can permit the construction of personalized cancer therapeutics
- generate the PDCs There is an immense variety of peptides (linear or cyclic) that have been exploited as carriers/targeting elements to successfully deliver the cytotoxic warhead to cancer cells [32]. These peptides are cell-specific and bind to certain receptors promoting their internalization. They are
Development of novel cyclic NGR peptide–daunomycin conjugates with dual targeting property
Beilstein J. Org. Chem. 2018, 14, 911–918, doi:10.3762/bjoc.14.78
- Vienna, Austria 10.3762/bjoc.14.78 Abstract Cyclic NGR peptides as homing devices are good candidates for the development of drug conjugates for targeted tumor therapy. In our previous study we reported that the Dau=Aoa-GFLGK(c[KNGRE]-GG-)-NH2 conjugate has a significant antitumor activity against both
- release; NGR peptides; oxime-linkage; targeted drug delivery; Introduction Targeted chemotherapy is one of the most promising approaches for selective cancer treatment that may decrease the toxic side effects of anticancer drugs. This therapeutic approach is based on the fact that tumor specific
- receptors are highly expressed on cancer cells/tissues. NGR (Asn-Gly-Arg) motif-containing peptides identified by phage display are suitable candidates for selective drug delivery. NGR peptides bind to CD13-receptors on tumor cells and tumor related angiogenic blood vessels [1][2]. CD13 is a transmembrane
Synthesis and in vitro biochemical evaluation of oxime bond-linked daunorubicin–GnRH-III conjugates developed for targeted drug delivery
Beilstein J. Org. Chem. 2018, 14, 756–771, doi:10.3762/bjoc.14.64
- receptors (GnRH-R) [1]. Therefore, these peptides are suitable for specific drug targeting to tumor cells. The native ligand of this receptor is GnRH-I (
- , 9Pro-EA] and triporelin [6D-Trp], which are used as pharmaceutical peptides to treat inter alia hormone dependent prostate and/or breast cancer [7]. Since the mid-1980s cytotoxic GnRH-I derivatives were developed and investigated to treat tumor cells [4][5][8][9]. Anthracyclines such as doxorubicin
- pathway. To gain further information about sequence–activity relationship of GnRH-III, we studied the impact of 6Asp on the efficiency of tumor targeting. Since it is known from the literature that an incorporation of D-amino acids (D-Aaa) in position 6 of GnRH-I and II peptides can lead to an improved
Enzyme-free genetic copying of DNA and RNA sequences
Beilstein J. Org. Chem. 2018, 14, 603–617, doi:10.3762/bjoc.14.47
- sequence long enough to hybridize stably to complementary strands were formed. Such strands may then be the templates or primers required to start enzyme-free copying. Further, the general condensation buffer noted above gave rise to the spontaneous formation of ribonucleotide- or RNA-linked peptides [64
- ]. These peptides are linked via their N-terminus to the ribonucleotide portion as phosphoramidates, which is why we refer to them as "peptido RNAs". Peptide chain growth on the 5'-phosphate is much faster than the background reaction [65], and will thus predominate over background oligomerization of amino
- considered a prebiotically relevant activating agent [67], and it has previously been used in experiments aimed at generating peptides in the absence of enzymes or a ribosomal machinery [68]. Reactions with cyanamide are much less efficient than with EDC, so that successful primer extension has not yet been
Mannich base-connected syntheses mediated by ortho-quinone methides
Beilstein J. Org. Chem. 2018, 14, 560–575, doi:10.3762/bjoc.14.43
- were also formed in around 90% yields under microwave irradiation (Scheme 7). Miscellaneous reactions It is also known that o-QMs could cross-link two biologically important molecules such as peptides, proteins or nucleic bases. (see section Biological properties) Achieving the reaction under
Stimuli-responsive oligonucleotides in prodrug-based approaches for gene silencing
Beilstein J. Org. Chem. 2018, 14, 436–469, doi:10.3762/bjoc.14.32
- facilitate their uptake, a TAT-peptide delivery domain was conjugated to the siRNNs via A-SATE phosphotriester groups. Hence, a chimeric passenger strand containing four A-SATE phosphotriesters duplexed with an RNN guide strand was conjugated to the delivery domain TAT peptides. The resulting conjugates
- possessing only ≈25% of neutralized phosphates and four TAT peptides were optimal to enter cells passively. Once inside the cells, the SATE groups were efficiently removed by esterases, leading to siRNAs that are induced according to knockdown with apparent EC50 values in the low nanomolar range and in a
Synthesis and biological evaluation of RGD and isoDGR peptidomimetic-α-amanitin conjugates for tumor-targeting
Beilstein J. Org. Chem. 2018, 14, 407–415, doi:10.3762/bjoc.14.29
- synthetic peptides or peptidomimetics containing these sequences have been prepared and show low nanomolar IC50 values for integrin αVβ3 binding [21][22][23][24][25][26][27]. A number of cyclic RGD and isoDGR ligands containing a bifunctional diketopiperazine (DKP) scaffold have been developed by the
Photocatalytic formation of carbon–sulfur bonds
Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4
- aryl diazonium salts to give the corresponding diaryl sulfide in high yields. Very recently, Noël and co-workers applied the above-mentioned concepts for the selective arylation of cysteine and cysteine-containing peptides in batch as well as in a photomicroreactor (Scheme 18) [49]. They were able to
Aminosugar-based immunomodulator lipid A: synthetic approaches
Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3
- integrity and antigen presentation, decreases susceptibility to antimicrobial peptides and enhances pathogenicity [25]. In some LPS, the lipid A phosphates are post-translationally modified by substitution with the compounds that reduce the net negative charge of LPS, such as phosphoethanolamine in E. coli
- peptides (CAMPs) and antibiotics [25][32][33][34]. Activation of the innate immune response by lipid A/LPS requires a consecutive interaction of lipid A with lipopolysaccharide-binding protein (LPB) [35], glycosylphosphatidylinositol-anchored surface protein CD14 (a differentiation antigen of monocytes
Recent applications of click chemistry for the functionalization of gold nanoparticles and their conversion to glyco-gold nanoparticles
Beilstein J. Org. Chem. 2018, 14, 11–24, doi:10.3762/bjoc.14.2
- types of carbohydrate–protein interactions, it is therefore essential to present carbohydrates in a multivalent fashion. For that purpose, different scaffolds, such as peptides, proteins, lipids, and synthetic polymers, have all been used [7]. The search for better scaffolds for the presentation of
- system was then used for the detection of amyloid-β peptides [74], whose aggregation is responsible for Alzheimer’s disease [75]. In 2014, Fairbanks and co-workers reported a one-pot aqueous compatible method for making various triazole-linked glycoconjugates via intermediate glycosyl azides, which then
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